# Desperatly looking for driver (updated kennan driver?)



## MikePL (Feb 14, 2008)

OK, so I bought these drivers in the past:
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=2982 

They are absolutely good stuff, very reliable and efficient. And they have the input range that suits me (automotive purposes). 

The problem is that I ordered them once again from Kaidomain in mid November. I paid for 20 pieces. I don't remember if they were available at the time, but I think I would have seen the 'out of stock' text. 

The thing is that the drivers have not arrived yet, after three months. Fortunately I have managed to enter into a conversation with people from KD (which is like a miracle, as they usually do not reply) and they told me that the supplier give the item in really small batches, so I'm waiting in queue. I can get a refund if I want.

But I want the drivers because I need them. So does anybody know where I can buy (at a similar price) drivers for 12-15V (this range interests me)?

I am stuck with my projects for three months, waiting like an idiot.


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## Gryloc (Feb 14, 2008)

*Re: Desperatly looking for driver*

MikePL,

It is too bad that it has been taking you so long to get those drivers. I cannot believe that it takes 3+ months to gather a total of 20 drivers from suppliers. Does this mean other peoples small orders (1-2 of the drivers) are being ignored until your order is complete? Maybe they keep a few in reserve for those with small orders. Either way, yikes! If there are people demanding that many of those specific driver boards, then you would think that someone would ask for more from the supplier/manufacturer.

Anyway, I am as equally interested in the same thing as you. I plan (well, planned) to buy 12 to 16 of those driver boards for a new automotive headlight project. That seemed like a decent driver (specs wise), and I have tested one of the boards and it worked as I wanted. Now I do not know if I even want to bother with waiting 3+ months for these nice drivers.

I wish I could get my hands on just the IC circuits, as I feel that I may be able to get the needed components and make my own driver boards, but every place that distributes them are in Chinese. Does anyone know where you can find these IC cicuits (Micro-Bridge PT4105), or where you can buy circuits that feature this IC? Could anyone help us English speakers with ordering from these sites? I am afraid to work with them with only using a Google translation. There is still a big communication gap there!

As MikePL asked, can anyone make any recommendations for a suitable driver that could serve as an alternative?

Thank you MikePL for figuring this out for us. It is unfortunate for your long wait. I think that you may have saved a few of us from going through the same gruesome thing...

-Tony


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## LukeA (Feb 14, 2008)

*Re: Desperatly looking for driver*

Well, DX has p60 dropins with 3-18V input. (here) I know they're more expensive than the KD boards ($10.14), but you also get emitters and reflectors.


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## JB01245 (Feb 15, 2008)

*Re: Desperatly looking for driver*

Have you seen these? Look interesting.

http://www.cutter.com.au/proddetail.php?prod=cut755


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## MikePL (Feb 15, 2008)

*Re: Desperatly looking for driver*

Looks interesting. But is it just the chip for sale or the entire plug&play board?


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## kavvika (Feb 15, 2008)

*Re: Desperatly looking for driver*

LukeA: So are you saying that you know the drivers in DX #6090 = KD Kennan boards, or are you just basing that off the specs and pictures? Either way, I can't believe I missed that before, as I've been looking for a few Kennan's for a while now!


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## jtr1962 (Feb 15, 2008)

*Re: Desperatly looking for driver*

Part of the problem is he's selling those way too cheap. He's probably out of stock because he can't get parts for new boards cheap enough and doesn't want to raise his price. I would have to charge at least twice that to sell a similar board, and that would be in large quantities (500+ pcs). Orders of 10 or 20 would probably be $11 or $12 each.

I don't see how Cutter can afford to sell that board so cheap and make a profit, either. The parts likely cost as much as he's selling it for. It's probably a loss leader so he can sell LEDs.


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## MikePL (Feb 19, 2008)

*Re: Desperatly looking for driver*

Hi,

So is this 'driver' sold by Cutter a whole driver (ws we see in the photo) or is it just the chip? The description is ambiguous as well as the datasheet.

They say:
_The ZD850 is available in a thermally enhanced 16-pin exposed TSSOP green package.

_So is it only the 16-pin chip or is it the whole board with chip and the other components?


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## JB01245 (Feb 19, 2008)

*Re: Desperatly looking for driver*

If you click on the Evaluation board datasheet it reads:

"The ZD850 is a constant off-time, high power LED driver IC using a Buck Converter Topology that is capable of driving up to a 1.5A of output current. It operates from an input voltage range of 4VAC to 16VAC or 5VDC to 27VDC and generates a regulated programmable constant output current for high power LED's."


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## MikePL (Feb 19, 2008)

*Re: Desperatly looking for driver*

Well, yes... But to me it isn't clear whether it's only the 16-pin chip or the whole board with all the components. You know, I am an amateur when it comes to electronics. So I still don't know what's included in the price...

What is 'driver *IC*'?


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## JB01245 (Feb 19, 2008)

*Re: Desperatly looking for driver*

Driver Integrated Circuit?


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## MikePL (Feb 19, 2008)

*Re: Desperatly looking for driver*

OK thanks, if it's the whole circuit then I will buy a few and tell you guys if they are really good.


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## WeLight (Feb 19, 2008)

*Re: Desperatly looking for driver*

There are 2 separate products the ZD850 Chip, this is the device, then there is an evaluation board used to assist in evaluating the chip in a plug and play fashion. Hope this is clear


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## Gryloc (Feb 19, 2008)

*Re: Desperatly looking for driver*



WeLight said:


> There are 2 separate products the ZD850 Chip, this is the device, then there is an evaluation board used to assist in evaluating the chip in a plug and play fashion. Hope this is clear



Thanks for chiming in WeLight. Are you saying that this is just the IC then, or the evaluation board with the IC on it? I searched for "ZD850" but the above page is the only result (trying to find the evaluation board if possible). I could not find anything else. If this is just the driver, then where is the evaluation board?

The reason I feel that it is the entire driver is because it shows a picture, it mentions being of the buck topology (as though you have the choice with the bare IC, so you can design the circuit with the boost or buck setup needed), and finally, it says "The ZD850 is available in a thermally enhanced 16-pin exposed TSSOP green package" as though that is what you may get.

Can you please clarify this for us? I am interested in buying several if it is the complete (or somewhat complete) circuit including the board and IC. If it is the bare IC, I am still interested, but I will have to re-consider a few things.

Do you have any other similar driver circuits for sale? MikePL, are you interested in driving 2-4 LEDs from an automotive power source, or just a single LED? I can help you by keeping an eye out for you. I am need something to power three in series (so a buck circuit), but I may be able to work with a huge boost circuit and power all 9 or 10 LEDs in series. The Chippo may work, but that is still much more expensive (though simpler to work with). Dimming for me (or programmable current via a resistor) is highly desired so I can change between two custom levels. The KD circuit is nice, but I still would need to switch between one and two with their output in parrallel to change current levels (if the circuit will allow -hopefully no interference between the ICs). I would like to stay away from too pricey of circuits, but I would like to keep things rather simple still. A single circuit with multiple outputs or a boost that can handle them all in series would be nice, even if custom made. I may be able to work with ICs and design something from the specs, but keep that simple and the IC not too small of an SMD component, and I will be happy.

Thanks all for your input!

-Tony


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## JB01245 (Feb 19, 2008)

*Re: Desperatly looking for driver*

The Cutter website magically updated. Is showingthe chip costing $2.65 USD and $20 USD for the evaluation board. I fold.


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## Gryloc (Feb 19, 2008)

*Re: Desperatly looking for driver*

Thank you JB012345. That is too bad. Damn! Well the search continues... The bare IC may still work, but the time going in to driver design may not be worth it for me now I think of it, even if it may be cheaper. Please help us, all...

-Tony


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## MikePL (Feb 20, 2008)

*Re: Desperatly looking for driver*

They updated the website because I asked them the question whether this is just the chip or chip+board. Got no reply but the site got an update. 

What's going on with those drivers and boards? Today I can buy a new graphics card for $35 and it has a 300-pin processor, a big board, lots od small components which are quite complicated. 

On the other hand there is a driver with a very simple board, a few resistors, a coil of some kind and yet it costs $23 !!!

That's what I call extreme price boosting.

Gryloc, I will reply later as I have to leave my computer right now..


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## JB01245 (Feb 20, 2008)

*Re: Desperatly looking for driver*

Here is another driver I have found that might work for you -

http://parts.digikey.com/1/parts/405183-eval-board-l6902-series-eval6902d.html

These are only $13. I already have one, just haven't played around with it yet.

Here is the link to the datasheet
http://www.st.com/stonline/products/literature/bd/12769/eval6902d.pdf


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## jtr1962 (Feb 20, 2008)

*Re: Desperatly looking for driver*



MikePL said:


> What's going on with those drivers and boards? Today I can buy a new graphics card for $35 and it has a 300-pin processor, a big board, lots od small components which are quite complicated.
> 
> On the other hand there is a driver with a very simple board, a few resistors, a coil of some kind and yet it costs $23 !!!
> 
> That's what I call extreme price boosting.


The graphics cards are often made in the tens or hundreds of thousands by pick-and-place machines and IR soldering, creating huge economies of scale. Also, buying parts by the 100K is way cheaper than by the thousand. That accounts for part of it. Another part is for whatever reason all these LED driver ICs seem to be overpriced by the manufacturer for what they are. $3 for the IC is what really kills the pricing on this stuff. The coils can be expensive also, depending upon where you get them. I've made larger boards for a customer, and it was all I could do to get under $10 each in 500s while still making a reasonable profit. And I have zero overhead since I make them at home. I don't think $23 is entirely unreasonable for a small run of a very niche product when the company needs to pay its employees.

Stay tuned-in time (meaning perhaps a year or two) I may start selling some driver boards on CPF once I get rid of my dad's hobby crap and have time and space to do so. I have to evaluate how much they're likely to fetch versus my manufacture cost and labor time.


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## MikePL (Feb 20, 2008)

*Re: Desperatly looking for driver*

Yes, I agree that machines cut on costs, but come on... $20 or even $30 for a LED driver is insane. 

The same applies to 110-220V LED drivers. I've seen prices in the range of $10-40, while I use cell phone chargers with great success. They have a range of 600-800mA, depending on model, and cost $1-$2. The internals are also similar. I don't know if chargers are hand-made but they cost a few dollars and included in it are components, profit for the factory and profit for the seller. LED drivers are not much different. They should cost no more than $4 and I think that production costs are not the reason for a high price, but simply the fact that LEDs are in fashion and producers want to suck out all the money they can before prices drop.

Gryloc, I am constantly looking for drivers and must admit that price is the most important factor for me. I am interested both in multi-LED drivers as well as drivers for one LED. For example, I have 4 lights in my car doors. If the driver is expensive I will have to route additional wiring in order to use one driver for all 4 lights. If drivers are cheap I will simply save myself lots of time and 'waste' a driver per door. The same applies to blinkers and other lights... This is why I prefer to use cheap drivers. It is much easier to preserve the factory car wiring rather than doing it all from scratch.

My budget for drivers is $100 (shipping incl.) so if you find anything that can get mi a final price (with shipping) of $2-4 per driver, then I would be happy.

Damn, I never thought that finding drivers would be such a problem and that they would exceed the price of a LED. Our situation is like having candles but no matches to light them.


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## jtr1962 (Feb 20, 2008)

*Re: Desperatly looking for driver*

$3 or $4 a driver might be very doable if those driver ICs would drop a bit in price. For example, if I could make a driver with about 4 or 5 parts costing less than $1 total, including the PC board, then I can sell it for perhaps $3.50 or $4 each, and still make a reasonable profit, provided I can get interest in 250 to 500 pieces. I'll add "ultra-low cost driver" to my list of "to be designed", but I probably won't have time to do it anytime soon. Also note that these things get way cheaper when size isn't an issue. A wall wart is huge compared to something to fit in a AA flashlight. That accounts for a good deal of the higher cost. I do agree $30 for a driver is ridiculous in most cases.

I use wall-warts or plain AC transformers, combined with one of my drivers, for all my 120VAC stuff. I agree those 120VAC LED drivers are way overpriced (and most are huge-the size of fluorescent ballasts).

BestHongKong has some 12V drivers for $5.95 here. Still a little higher than you're looking for, but not anywhere near $23.


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## frenzee (Feb 20, 2008)

*Re: Desperatly looking for driver*

I was wondering if anyone here has ever used the Linear LT3467A in a boost circuit. This thing is unbelievably tiny, smaller than an ant, but it's supposed to deliver up to 1.1A of switching current. Although the LTSpice simulator that Linear has shows that it can come up to and sustain my needed current in under 1 millisecond using only a 3.2µH choke, I am having a hard time believing those figures. I am about to start building the circuit, but I imagine it will be quite a challenge considering the ultra-small form factor. I was wondering if anyone has had any experience with this particular driver or with soldering the DFN form factor in general (3mm x 2mm, 8 legs).


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## snarfer (Feb 21, 2008)

*Re: Desperatly looking for driver*

I've been doing a lot of research on drivers lately. 

Not so sure on the LT3467/3467A. On the plus side it's small and has an integrated switch. Also switches very fast. But nearly two dollars a chip in quantity seems pretty steep. Also it appears to be voltage-mode control, not current-control, so how do you deal with Vf variation and heat?

My latest conclusion is that the best solution, at least for my purposes, where I need to be able to control via a microprocessor at fairly high speed for color mixing, is actually the ZXSC310 (mouser sells them for something like 70 cents, and they're only 38 cents in quantity!) run in buck mode with an external transistor switch. The other cool thing about the ZXSC is that the sense resistance threshold is only something like 20 mV, so a nice gain in efficiency there over other constant current solutions. And in boost mode it can source current from some ridiculously low voltages.

Well I haven't got them yet. I'm in Thailand and it takes forever to get stuff from the US. But anyway just wanted to share that, since it seemed like a much better 
(and cheaper!) driver solution than anything else I've seen out there.


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## jtr1962 (Feb 21, 2008)

*Re: Desperatly looking for driver*

The ZXSC310 won't work here-the maximum input voltage is only 8V, requiring an external voltage regulator. I remember when I was researching drivers a lot of the Zetex stuff at first seemed good. However, once you looked at the data sheets, you found the need for external pass elements (that's another part to be soldered, irrespective of cost), and in some cases (as with the ZXSC310), the need for extremely low-value (i.e. expensive) sense resistors.

Unfortunately most (all?) of the integrated buck drivers, which is what is needed in the original poster's application, do indeed run $2 or more even in quantity. A lot of those which might be marginally cheaper (i.e. external pass element) had other restrictions.

One Zetex driver I'm liking more and more is the ZXLD1360. This is a buck driver with an input voltage range of 7V to 30V. Only $1.40 in 500s, internal pass element, 100 mV sense voltage (thus can use normal value cheap sense resistors), low parts count ( only need the inductor, Schottky diode, sense resistor, and input capacitor ), and an external input for either current modulation or PWM. Still not cheap enough to make a $4 retail driver board with (for me anyway), but at least a step in the right direction. I could probably sell a ZXLD1360 based driver board at perhaps $6 each were I to get interest enough to build 500 pieces.


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## snarfer (Feb 21, 2008)

*Re: Desperatly looking for driver*

I was just looking at prices for sense resistors. 0.05 ohm "current sense" resistors are like 40 cents apiece! But then when you check the "regular" 0.10 ohm resistors, they are like 2 cents. I guess with only 19mV you might be able to use a bit of PCB board instead.

I hadn't thought about how annoying it is to have the extra pass components to deal with. In my case it was not such a big deal as I was researching how to put a very large number on one board, so a power supply was a given anyway.

Actually the OP said 12-15 volts input, so the boost regulation was kind of a sidetrack to that.

I see what you mean about the ZXLD1360. That part appears to be the best fit for the needs of the OP.


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## space (Feb 21, 2008)

*Re: Desperatly looking for driver*

The LT3467 isn't really a good choice for hi power (500-1000ma) LED driving. It just won't be able to produce enough "juice", and efficiency will hurt when one start to squize much current from it. Current feedback also is more complicated unless one goes for low efficiency design. 
For constant voltage design and output up to 350ma I think it could do ok.

(I've used the LM2623A myself which is close to the same IC but with 2,2A switching current.)


space


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## nanotech17 (Feb 21, 2008)

*Re: Desperatly looking for driver*



MikePL said:


> OK, so I bought these drivers in the past:
> http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=2982
> 
> They are absolutely good stuff, very reliable and efficient. And they have the input range that suits me (automotive purposes).
> ...




would like to try this - http://www.besthongkong.com/product_info.php?cPath=19_51&products_id=447


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## jtr1962 (Feb 21, 2008)

*Re: Desperatly looking for driver*



snarfer said:


> I was just looking at prices for sense resistors. 0.05 ohm "current sense" resistors are like 40 cents apiece! But then when you check the "regular" 0.10 ohm resistors, they are like 2 cents. I guess with only 19mV you might be able to use a bit of PCB board instead.


That's probably exactly what the designers of the ZXSC310 have in mind. It can even work if precision isn't too important. At best with PC board traces you'll be able to get perhaps 20% repeatability from lot to lot due to variations in copper thickness, undercutting, etc. Add to that variations in copper resistance over temperature and that's probably 25% tolerance. Still good enough for a lot of applications I suppose, although I usually aim for 5% or less in the stuff I do. Last run most of my boards fell within a 2% error band of nominal. 



> I hadn't thought about how annoying it is to have the extra pass components to deal with. In my case it was not such a big deal as I was researching how to put a very large number on one board, so a power supply was a given anyway.


A power supply to a bunch of driver ICs on a single board is quite feasible. Regarding the extra pass components-it's another cost if you're doing mass production. I figure $0.15 to $0.25 to mount each extra component when I calculate costs. One driver design I did startd out with 14 components. Next interation will be only 7. That's going to cut in excess of $1 off the final price to the customer, as well as making my life easier assembling these things.

I suspect the price of these driver ICs will crop dramatically in the next few years. For IC manufacture, hundreds of thousands for such niche products is what results in these high costs. Once LEDs become ubiquitous in cars and homes, they will be selling millions of these driver chips. Probably the low price on ZXSC310 is already the result of this driver being used by the millions. We can hopefully expect a lot more of the $3 or $4 driver chips to fall under $1 in a couple of years, making $3 driver boards a reality.


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## MikePL (Mar 5, 2008)

*Re: Desperatly looking for driver*

Soo.. when I was about to give up, the drivers from Kaidomain arrived. After over three months. But either I got the wrong driver or maybe the driver was updated.

The result is that I have 'some' drivers and I don't know if it's the updated kennan or how to connect the cables to it. Below are photos of the typical kennan driver and the photo of my new kennan? driver.

The typical one:






My new driver:


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## jtr1962 (Mar 5, 2008)

It's the same IC (PT4105). This looks like it's probably the datasheet. Just figure out where the leads went on the old board, and make sure they connect to the same places on the new one. Ground is probably the cathode on the Schottky diode (i.e. the side without the band) and also pin 7 of the IC. +12V will be pin 3 on the IC. The LED anode should be that round pad on the left of the inductor. The LED cathode will be pin 8 on the IC (the FB pin).


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## MikePL (Mar 5, 2008)

So please correct me if I'm wrong. I only marked the LED connections as the input positive and negative cables can be soldered on the other side of the board.






Please, can someone confirm that these connections are right? I do not want to send my drivers to heaven and have to wait another 3 months for them...


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## jtr1962 (Mar 5, 2008)

MikePL said:


> So please correct me if I'm wrong. I only marked the LED connections as the input positive and negative cables can be soldered on the other side of the board.
> 
> 
> 
> ...


That's definitely correct. You can't destroy a buck board by connecting the LED wrong anyway, only by connecting the power leads wrong.


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## MikePL (Mar 5, 2008)

OK, thanks for help. If anything out of the ordinary happens then I will keep you posted. I've also heard that this driver was to be updated and probably I got the updated version.


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## Gryloc (Mar 5, 2008)

Was that the reason that it took so long to ship? I am still interested in these, but I am afraid to be stuck waiting. I looked the board over and it seems silly to make the layouts so much more complex. The old driver was so simply laid out, and it is hard to mess things up since the components were pretty spread out. I see the very same components in the new one as the driver before. I studied the new one to see how it compares to the old one, as well as the datasheet schematics, but I could not see where all the traces went (hidden under the IC and hard to see). I think that everything is fine. I hope it is. :shrug:

-Tony


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## MikePL (Mar 6, 2008)

They are still marked as 'out of stock' so probably they are shipping the drivers to all those who ordered them long ago.


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## PeterC (Mar 6, 2008)

Just collected my long oustanding order for 5-off Kennan (KD sku 2982) from the post office. These are of the new build (with diode wires supplied, but not fitted).

Ordered on 7th Jan '08
Delivered on 5th March '08

Patience is obviously required if you order these!

The circuit of the original design was very close to the typical application circuit shown on the Micro-bridge data sheet for the PT4105 (and applied the recommendations about pcb layout given on the sheet). The new design appears to be based on the same application circuit, but has a couple of additional components (with spaces for several more).

It is not easy to see exactly how the components are connected within the circuit! A bright light, magnifier, and continuity meter/DMM will be needed to reverse engineer the design and see exactly what we have.

My initial thoughts, however (if we're lucky), is that the extra pads and pcb tracking may give some scope for easier mods to the driver board than the original one offered (e.g. changing the feedback circuit to alter the current supplied to the LED.


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## jtr1962 (Mar 6, 2008)

PeterC said:


> My initial thoughts, however (if we're lucky), is that the extra pads and pcb tracking may give some scope for easier mods to the driver board than the original one offered (e.g. changing the feedback circuit to alter the current supplied to the LED.


That's exactly what it looks like to me. See page 5 of the datasheet for some typical dimming methods. The probably have the extra pads so one or even all of these methods may be employed. Good idea since it adds nothing to the cost of manufacture but greatly increases the flexibility.


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## MikePL (Mar 8, 2008)

Hmmm... I've got a problem. It seems that the connection above is wrong. Today I wired two drivers that way and connected an LED. The LED chip was barely giving some light. I thought that maybe the driver is dead, so I used the other one. I got the same results, the LED was so dim that it was barely visible. Input voltage was 12V from a computer PSU.

So do you have any other suggestions on how to connect the LED wires?


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## jtr1962 (Mar 8, 2008)

Try connecting to the other side of R2 (there's a pad between R1 and R2 which looks like a connection pad). It seems R2 is there to protect the IC. Problem is when you connect directly to pin 8 as per the schematics in the datasheet current will be limited to well under 1 mA due to the presence of R2.


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## MikePL (Mar 8, 2008)

Thanks for help. It now works absolutely fine. Hooray, I finally have them damn drivers 

Edit: just to clarify what connection we are talking about, I've decided to post another image.

This is the right connection of the LED wires:


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## jtr1962 (Mar 8, 2008)

Glad to be of help! Enjoy the drivers!


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## space (Mar 8, 2008)

Received my two drivers from Kaidomain yesterday, 8th of March. Ordered 12th of January. They have the same pcb's as MikePL, but they have all components except for R6 connected. Will post pictures later. Havn't tried them yet.

space


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## TorchBoy (Mar 8, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



jtr1962 said:


> See page 5 of the datasheet for some typical dimming methods. ... all of these methods may be employed.


So the extra IC would be for PWM dimming?

Why do some of these photos have a 22µH inductor and some a 47µH one? (I think those units are right.) I noticed that for the first version too. What difference does more than doubling the value of the inductor make?


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## jtr1962 (Mar 8, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> So the extra IC would be for PWM dimming?
> 
> Why do some of these photos have a 22µH inductor and some a 47µH one? (I think those units are right.) I noticed that for the first version too. What difference does more than doubling the value of the inductor make?


Increasing the inductor value just smooths the current to the LED a bit more, that's all. The new version uses a smaller value inductor but has a ceramic cap in parallel with the LED. The capacitor also smooths the current.

Regarding PWM, not sure what extra IC you're referring to here. Can you be more specific? In all the photos I see there's just the PT4105 driver IC. All the rest of the parts are either resistors, inductors, capacitors, or diodes.


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## TorchBoy (Mar 8, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



jtr1962 said:


> The new version uses a smaller value inductor ...


Does it? This pic shows it marked 470, and has the board fully populated except for R6.



jtr1962 said:


> Regarding PWM, not sure what extra IC you're referring to here. Can you be more specific? In all the photos I see there's just the PT4105 driver IC. All the rest of the parts are either resistors, inductors, capacitors, or diodes.


Have you noticed that all the photos on the product page are new?  In the first photo (link above) it's called IC1 and marked as 82FE.


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## jtr1962 (Mar 8, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> Does it? This pic shows it marked 470, and has the board fully populated except for R6.
> 
> 
> Have you noticed that all the photos on the product page are new?  In the first photo (link above) it's called IC1 and marked as 82FE.


Sorry, I didn't even look at the product page until now, so I really had no idea what you were referring to. Electronically, there's not much difference between a 22µH and a 47µH inductor. It was probably a matter of one part being cheaper or more available than the other. IC1 is probably a voltage regulator but it could also be a transistor or a diode mislabeled as an IC. It does indeed look like it has something to do with PWM. If I had to guess, I'd say it's a transistor which pulls the FB pin high in order to turn the LED off via a PWM signal.


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## MikePL (Mar 9, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*

Hmm... I wonder what those extra components add to the driver? All the drivers I have are just like the one in the photo on top of the page. No IC1 no resistors... but I have the R6


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## TorchBoy (Mar 9, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



jtr1962 said:


> IC1 is probably a voltage regulator but it could also be a transistor or a diode mislabeled as an IC. It does indeed look like it has something to do with PWM. If I had to guess, I'd say it's a transistor which pulls the FB pin high in order to turn the LED off via a PWM signal.


Sounds good. 3 pins, so I wouldn't think diode.



MikePL said:


> Hmm... I wonder what those extra components add to the driver? All the drivers I have are just like the one in the photo on top of the page. No IC1 no resistors... but I have the R6


And it's just a link. :thinking: Apparently a board tuneable for multiple applications. We could do with some sort of application notes for this particular board.

If the set resistor is 0.2 ohms, is the output now 1A instead of the old 750mA?


----------



## mike2g (Mar 11, 2008)

I'm sorry but the workings of this board is beyond me. Does anyone know what resistor could be used to replace the supplied 0.2ohm one that would produce 350mA?


----------



## TorchBoy (Mar 11, 2008)

The datasheet says a 0.57 ohm resistor will give a fixed 350mA output. (I haven't received the new version of the board yet, so I haven't seen if there's an easier way provided by all the new resistors etc.)


----------



## [email protected] (Mar 12, 2008)

I got some of the new Kennans with IC1, R4, and R5, but no R6. The extra parts make the driver shut down for input voltages below 6.2 volts. My guess is these parts are designed to shut down the driver when 2 Li-Ion cells driving it get below their safe operating voltage.

It seems you can pretty easily bypass this "feature" by shorting out R4. Or else by removing IC1, R4, R5 and then installing a piece of wire for R6. I'm a little bummed to have to be doing this on the drivers I got. I really like being able to drive a LED off of 4 NiMh batteries, and with IC1 installed, that's not gonna happen.

Mark


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## TorchBoy (Mar 12, 2008)

[email protected] said:


> Or else by removing IC1, R4, R5 and then installing a piece of wire for R6.


Sounds like what the initial run of this new version had, as per the pic posted by MikePL.

Nice deductive work, BTW.


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## space (Mar 12, 2008)

I've tried to make a schematic of the boards I received and taken a few pictures. One of my boards has a 22uH and the other a 47uH inductor. They also have different R2, one 5k1 the other 3k.

As far as I can read from the datasheet (PT4105), the CE-pin (chip enable) needs at least 1.5V to "start" the chip. When going below 0.3V it will shut down again. I agree with Mark that the R4+5+7 and IC1 have the task of regulating the voltage to the CE-pin and thereby enabling / disabling the PT4105 at certain supply voltages. By changing/adjusting these resistors one probably could change shutdown voltage to what ever one like.
























space


----------



## nein166 (Mar 13, 2008)

space said:


> space


 
Awesome Picture!
Oh and thanks for the the schematic. Changing the shutdown voltage would save my cells when running on multiple Li-Ions.


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## TorchBoy (Mar 15, 2008)

So are these in stock or aren't they? Has anyone had any shipped since the web site started claiming they are in stock again?


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## [email protected] (Mar 15, 2008)

So I finally tried removing IC1, R7 and R5 (if you pull off IC1 and R5 you don't need to bother with R4), then I shorted out R6. Everything seems to work fine.

But I noticed something different. With R1 set at .200 ohms, the driver drives the LED with about 1 amp of current. So the LED runs a lot brighter than previous versions of the driver (the old version of the driver ran at around .8 amps I think).

The LED now runs a bit hotter, which I would expect. And the driver chip now gets pretty warm, like too hot to touch after a few minutes. I looked up absolute max current for the driver chip and it's listed as 1.5 amps. But the recommended operating current is less than .7 amps.

Anybody try running one of these for a long time? My tests have all been pretty short, less than an hour. I'm wondering if these drivers are going to be more failure prone due to the higher current.

Mark


----------



## TorchBoy (Mar 15, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> If the set resistor is 0.2 ohms, is the output now 1A instead of the old 750mA?





[email protected] said:


> But I noticed something different. With R1 set at .200 ohms, the driver drives the LED with about 1 amp of current. So the LED runs a lot brighter than previous versions of the driver (the old version of the driver ran at around .8 amps I think).


Thank you for that confirmation. The datasheet indicates it shouldn't be run at 1A with less than 9V in, so I'm a little surprised at that change.


----------



## MikePL (Mar 23, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*

I have one more question about this driver. Can it be powered without the LED connected on the other end? I heard that some drivers need an output in order not to burn. I am about to make a light and I would like to have a switch which would either power one LED or three. While switching there is always a 'gap' which lasts 0.2s and I would like to know it such a repeated switching can damage it.


----------



## jtr1962 (Mar 23, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



MikePL said:


> I have one more question about this driver. Can it be powered without the LED connected on the other end? I heard that some drivers need an output in order not to burn. I am about to make a light and I would like to have a switch which would either power one LED or three. While switching there is always a 'gap' which lasts 0.2s and I would like to know it such a repeated switching can damage it.


In general, step-up drivers are the ones in danger of burning out if no load is connected. What happens is that the output voltage increases without limits until it exceeds the ratings of the pass element or the output capacitor. Once that happens, you get catastrophic failure (in layman's terms lots of smelly smoke). Some step-up drivers have output voltage limits to prevent this from happening.

Since this isn't a step-up driver, but rather a step-down one, this failure mode can't happen. With nothing connected the pass MOSFET will simply be driven at maximum duty cycle, and the output voltage will be a little less than the input voltage. This can't harm anything.


----------



## TorchBoy (Mar 23, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



jtr1962 said:


> Some step-up drivers have output voltage limits to prevent this from happening.


Would a zener diode do that job? :thinking:


----------



## jtr1962 (Mar 23, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> Would a zener diode do that job? :thinking:


It would in theory but it would have to be capable of absorbing the full LED current times the zener voltage. In other words, in theory yes, in practice no. A better solution is to feed back the output voltage via a resistor divider, and limit the duty cycle when it gets too high. Many step-up drivers have inputs for doing this.


----------



## zega (Mar 25, 2008)

How bout this one?
http://cgi.ebay.com/3W-LED-Driver-f...36323QQcmdZViewItemQQ_trksidZp1713.m153.l1262
In the menatime i have designed some discrete SMPS drivers (1 BJT and 1 MOSFET 1coil few res and caps) 90% eff in LTC cad in efficiency report (eff report is done wit a help of some tricks, cannot be done with discrete design), pricing of the parts is well under 1 $...
Ok i scrap coils from wasted PC PSU-s but it works great on small scale...
I have done 4,5W 54 10mm LED submersible LED drop in that work on 60V (boost) to drive 4x14LED in series in pulse mode and i am very satisfied with results!
I plan to work on that drivers a little more because they perform great for the price and lately i have fetish on simple as possible designs (no PWM controller or PIC used)...
z


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## romroro (Mar 28, 2008)

Hello all, I have a question about Kennan drivers.
I received it from KD, it works fine ( approximately 1A Vin=7.4V Vout=3.5V)
But I would like put two in a parallel design for an hight current design.
But importunately it doesn't works ( it works but at 800 mA  in place of 2000mA expected).

Is someone have design idea for do that works fine ?
Tks 
Rom
PS: please excuse my bad English.


----------



## TorchBoy (Mar 28, 2008)

romroro said:


> Hello all, I have a question about Kennan drivers.
> I received it from KD, it works fine ( approximately 1A Vin=7.4V Vout=3.5V)
> But I would like put two in a parallel design for an hight current design.
> But importunately it doesn't works ( it works but at 800 mA  in place of 2000mA expected).


I don't know about using the Kennan in parallel, but I see that the datasheet for the PT4105 regulator chip (used in the Kennan) indicates that 1A current output should only be used with at least 9V in, and it doesn't recommend anything over 750mA output at any input voltage. Perhaps the Kennan isn't the best driver for the job?


----------



## romroro (Mar 29, 2008)

Maybe you right, i'll look at effect with a bigger tension source ( 12 or 14 V ) and look at the result.

If someone one have an idea, i still looking for solutions.


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## zzonbi (Apr 4, 2008)

I've got exactly the same driver as MikePL, after a similar delay too, but mine doesn't work nowhere near 1A, as I'd like, but around 700mA, creeping under 600mA as things heat up. I also noticed an annoying hiss, probably the inductor. Any suggestions for sollutions?

Be careful when connecting this board to a PSU over 12V as ringing may damage the IC. They skipped the RC snubber originally recommended. It's true this isn't required with batteries, though. But the long wiring in a car may be an issue.

OT: Is expecting an other free replacement realistic and do you guys get those packets at your door, or do you have to collect them from the post office?


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## mike2g (Apr 30, 2008)

I recently got a few of the updated Kennan boards and am having trouble connecting to it. I followed the second diagram from MikePL's directions for (+) and (-) (which agrees with Jerry from KD). However my flashlight won't light up and I can't get any reading when disconnected on my multimeter. Poking around with the multimeter I found power as shown below. It seems that the negative contact is the same but the positive moved. From playing with the multimeter it seems as though the old positive is also negative (after positioning the positive probe as shown I moved the negative probe to the ? and got the same reading as when on the negative contact) :shrug:

I know nothing about what the pieces on the board are doing but I know where the multimeter says that there's power. Is my board configured properly? Will the board operate as designed as I've made the the connection and if not what should I do?

just a little background, maybe relevant:

This board is connected to 6AA eneloops in a 2D maglite. I have a quad SSC (2 parallel, 2 series) setup. The emitters are H-bin so I was expecting each emitter to receive around 350-375ma at approximately 3-3.25V. (6-6.5V in series). My multimeter shows that the batteries are supply approximately 7.8V right now on the board contacts so I'm assuming that there is sufficient voltage for the board (at least 1.3V over what I need). As I've shown it the flashlight lights up but I am disappointed in the output. The brightness is comparable to a single SSC being driven by 4AA at 800ma this driver, which should be around 200 emitter lumens. I had expected the quad scc setup to be putting out approximately twice that, 400 lumens (350ma per emitter = ~100lumens X 4 emitters = ~400 lumens).


----------



## R290 (May 5, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> So the extra IC would be for PWM dimming?
> 
> Why do some of these photos have a 22µH inductor and some a 47µH one? (I think those units are right.) I noticed that for the first version too. What difference does more than doubling the value of the inductor make?


 

I found this thread, as I too order these drivers for auto app.

The difference in the inductor has to do with the efficiency of the driver. 
If you go to webbench you can select different efficiency ratings and see the values change. Another reason is size, and cost, less copper is cheaper. 






From there web site


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## uk_caver (May 6, 2008)

mike2g said:


> ...This board is connected to 6AA eneloops in a 2D maglite. I have a quad SSC (2 parallel, 2 series) setup. The emitters are H-bin so I was expecting each emitter to receive around 350-375ma at approximately 3-3.25V. (6-6.5V in series). My multimeter shows that the batteries are supply approximately 7.8V right now on the board contacts so I'm assuming that there is sufficient voltage for the board (at least 1.3V over what I need). As I've shown it the flashlight lights up but I am disappointed in the output...


I'm not sure if there's quite enough headroom if the input voltage is 7.8V. At the very least, it'd be fairly borderline
I'd suggest trying to temporarily connect an extra cell or two into your setup and see if you get a brighter output.


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## TorchBoy (May 6, 2008)

uk_caver said:


> I'm not sure if there's quite enough headroom if the input voltage is 7.8V. At the very least, it'd be fairly borderline


KD's information said it needed 1V headroom for each LED being run, so the supply would need greater than 8.5V.


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## zzonbi (May 15, 2008)

"Is my board configured properly?"

Your board is either a new design, either in error, as it has a condensor instead of a resistor (R5). I would resolder the led wires on the round pads, short circuit R6 and then try again.

What are these H bins SSCs?


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## TorchBoy (May 16, 2008)

FYI "condensers" are normally called capacitors in English.


> Capacitors are occasionally referred to as condensers. This is considered an antiquated term in English, but most other languages use an equivalent, like "Kondensator" in German, "condensador" in Spanish, or "Kondensa" in Japanese.


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## zzonbi (May 16, 2008)

Hope you have the capacity to condense more English language (http://www.thefreedictionary.com/condenser), but thanks for trying to be "informative" ;-)


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## spun (May 16, 2008)

in answer to mike2g i also have one of these new kennan's with what appears to be another of the capacitors in place of the old R5. well it works fine for me running two rebels in series. i read positive at both where you show positive in your pic as well as at the normal round positive pad that my led's are attached to. however i'm getting a 12v reading of my source at the pin you show and the proper 6+v for the rebels at the normal pad. make sure your soldering doesn't bridge the round positive pad to the smd part to the left of it. i've also had a couple of these drivers arrive doa.


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## TorchBoy (May 16, 2008)

zzonbi - when synonyms are reasonably well known they aren't normally a problem, but the use of antiquated terms (in English, at least) may be a problem, for example because meanings change. I'm sure some people still like to use it, and it seems there are several non-English languages that still use a variant, but most people just won't understand what you're talking about, even if they know what a capacitor is. And I'd like to think that I did more than try to be informative - we now all know what you were talking about. QED.


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## Brownstone (May 16, 2008)

Not only is "condenser" no longer used in English to designate a capacitor, electrical engineers have reused the word "condenser" to designate a device used to manage reactive load in power systems.

"Condenser" still exists as a fossilized word in "condenser microphone", but that no more means "condenser" is a current word for "capacitor" than the phrase "spick and span" means "spick" is a current word for "nails".

P.S. - I did understand you though. Just don't start talking about Leyden jars, animal electric fluid, and the aether.


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## moonfish (May 16, 2008)

On motors, they are called condensers, as far as I know. But as far as the weird acronyms you guys use here that don't make sense, this seems trivial and a bit preachy.


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## TorchBoy (May 16, 2008)

*Re: Desperately looking for driver (updated kennan driver?)*



moonfish said:


> But as far as the weird acronyms you guys use here that don't make sense, ...


I've seen this angle before and I don't see the issue - I'm under the impression that forums and abbreviations go together, as it's a handy way to not have to type as much. You would do well to learn a few. (Whenever I see one I can't guess from context I look it up.)


moonfish said:


> ... this seems trivial and a bit preachy.


And it's now off topic as well.  If we all typed in our native language, understanding would drop considerably as there are a lot of people on CPF from non-English speaking countries. Your call on how important you think it is that we all understand what we mean by certain words. It doesn't need to be made into a big issue.


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## zzonbi (May 16, 2008)

"because meanings change... people just won't understand"
QED
I like the last part. It hasn't changed much last thousands of years.


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## TorchBoy (May 16, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



zzonbi said:


> "because meanings change... people just won't understand"


That quoting is a tad disingenuous. I said "people just won't understand" because they don't have a clue what a condenser _was_, which was a separate point from the meaning of words changing. But as I've said, people now know what a condenser was. Shall we get over it and move on? :kiss:


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## spun (May 21, 2008)

on a new(3 capacitor) kennan i've replaced the .2 ohm R1 sense resistor with .5 ohm and it's driving two rebels in series at 400ma now instead of the 950ma stock. at 12v in i'm measuring around 87% efficiency which fits the datasheet specs. my question is what wattage the .5 ohm resistor should be, i'm using two 1 ohm 1/4 watt resistors in parallel and they're not running hot at all.

second, a posting above has suggested modeling this circuit in webbench(webench.national.com) but the pt4105 is not a national semi part so is this possible? is there another modeling app for this circuit?


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## jtr1962 (May 21, 2008)

spun said:


> my question is what wattage the .5 ohm resistor should be, i'm using two 1 ohm 1/4 watt resistors in parallel and they're not running hot at all.


P = I²R = 0.4²*0.5 = 0.08 watts. This is about 1/12 of a watt. In other words, any resistor rated for 1/8 of a watt or more will suffice. 0805 size or larger should suffice.


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## thides74 (May 22, 2008)

I have just received some Kennans from Kaidomain. However, when measuring them, it seems that both output current and efficience is way off the specs.

Measuring the output current with a Cree Q5 I get 930ma and when measuring the efficience with a 3 x 18650 li-ion battery pack (Vin ~11,8 v) I only get an efficience of roughly 76%.

I have not done any kind of modification to the driver.

Can anybody confirm these results?


----------



## TorchBoy (May 22, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



thides74 said:


> Measuring the output current with a Cree Q5 I get 930ma and ... I only get an efficience of roughly 76%.


That's about right for the latest batch of Kennans. If you're handy with a soldering iron you can drop the output current and increase the efficiency.


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## spun (May 28, 2008)

trying the pot dimmer mod from the datasheet, pretty easy and 0-960ma. tried the 10K pot but a 5K has better range. will add a resistor in line with a still smaller pot to limit the ma top and bottom. i use the 10uf cap + 1 ohm r across the input(datasheet and above) as i'm running 12v. 

thanks jtr1962 for the help with my prior question.


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## brighter-lights (Jun 2, 2008)

Received the new drivers a week ago and they are the worst I received yet. 

The earliest version (old pcb) was perfect. 

I ordered again and waited...I contacted kaidomain here and he said I must be patient we will get an improved version... but this improved version keeps shutting down from overheating until I added a heatsink... 

This last version really sucks. 

When running one Q5 from 3 cell lipo the board cuts out every 5 minutes or so.... thermal shutdown... It runs so hot you can't touch it. 

12.56v battery (no load) 
12.47v input (load) 
Input current 380mA 
Output current 890mA

When the voltage reach 11v with load, input current is 440mA. 

It already had IC1 removed so I removed R5, R7 jumped R6 and put a .27ohm R2 in from an old board.... now it's much better... I can touch it... 

Input voltage 12.56v (no load)
Input voltage (load) 12.50v
Input current 280mA
Output current 730mA 

When the battery is empty at 10.5v the input current is 330mA

I'm trying the dimmer pot mod now. 

Why do they manufacture these things if the old one obviously were so much better and more efficient?


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## TorchBoy (Jun 2, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



brighter-lights said:


> Why do they manufacture these things if the old one obviously were so much better and more efficient?


My guess is supply and demand. Enough people think that ~1A output is automatically better than ~750mA output that KD gets it made that way. I've even seen people on CPF basically demanding their 1A buck board. That the efficiency of the IC drops from >86% to <67% and the thing gets toasty hot as a direct consequence isn't a consideration for all these people at all, or that the difference in brightness isn't very great; they don't _have_ a list of priorities.

Kai should know better though, and offer the old version as well, but perhaps he doesn't have a choice at a reasonable price, and he just has to accept what the manufacturer offers.


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## brighter-lights (Jun 4, 2008)

As per the dimmer pot modification above: 

Using the 100K across R2 and + 
and a 1K2 (with R2 removed) gives me :

Input: 12.5v 290mA, 
Output: 3.61v 780mA

Just what I want!


----------



## saabluster (Jun 5, 2008)

*Re: Desperatly looking for driver*



jtr1962 said:


> provided I can get interest in 250 to 500 pieces.


You will have my support. :thumbsup:


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## ace0001a (Jun 6, 2008)

I've recently done a Quad Cree 3D Mag mod using 2 of these drivers in parallel running 2 emitters in series each and using a 9AA-to-3D battery adapter. I thermal epoxied the drivers IC side to the inside of the heatsink. So far it seems to run well. I've had the light on for as long as 20 minute stretches and it the light gets warm but not really hot. My Kennans are fairly recent and are of the newer design. Like the Sandwich Shoppe's Shark driver, I think the key is making sure you heatsink the driver well.


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## waTom (Jun 18, 2008)

I hope this is the right thread as it is about the kennan driver (mainly).

I would like to use one for a one led flashlight that should be powered by two cr123a batteries but also be able to take 18650.

The description says "Total input voltage must be 1-3V higher than output voltage" but it doesn't say what happens if not. Does the driver simply stop working or would it be direct-drive? :help::shrug:


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## uk_caver (Jun 18, 2008)

waTom said:


> The description says "Total input voltage must be 1-3V higher than output voltage" but it doesn't say what happens if not. Does the driver simply stop working or would it be direct-drive? :help::shrug:


With an (older) Kennan I have, if running a single Cree off 3xNiMH (~3.45V getting to the Kennan due to the presence of a series diode for reverse-voltage protection), I was getting ~270mA draw from the cells, and presumably about the same current going to the LED.
At that current, there was 0.27V drop through the Kennan circuitry.


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## waTom (Jun 18, 2008)

Thanks!


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## kosPap (Jul 18, 2008)

double post, sorry...


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## kosPap (Jul 18, 2008)

Hi guys? How about this version of the Keenan board?






link to supersize image

this one is missing the black part next to the inductor...

I cannot read it any further and I wonder if the - wire is soldered properly. It seems like it connects both the R200 and 622 parts...


----------



## uk_caver (Jul 18, 2008)

R1 and R2 are connected anyway (see circuit diagram in post #53)

In the circuit you posted a picture of, R6 is present as a 6k2 and R7 is missing - that does a permanent pull-up the Chip Enable input (not sure why they used a resistor there, rather than a shorting link - maybe to make it easier to add external pull-down for on/off control?)

Also, R4 is a 1R0 resistor and R5 has been replaced with a capacitor, presumably to form the 1R0/10u (or similar) series combination, as recommended in the PT4105 datasheet for use at >=12V input.

That looks like a smart thing to do if dispensing with IC1 - I think I'll probably do it myself on some Kennans I'm using in a battery charger I'm working on.


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## kosPap (Jul 19, 2008)

uk_caver said:


> R1 and R2 are connected anyway (see circuit diagram in post #53)
> 
> In the circuit you posted a picture of, R6 is present as a 6k2 and R7 is missing - that does a permanent pull-up the Chip Enable input (not sure why they used a resistor there, rather than a shorting link - maybe to make it easier to add external pull-down for on/off control?)
> 
> ...


 
friend you lost me here....in laymans terms was that an improvement of the Kennan board style? What do you mean by the*>=12V input* reference? taht the board it is optimized for that voltage range? What do you mean by the term *pull up*?

also R1&R2 are connected but doesn't things change if the led input wire is placed between them? (are they in a series or parallel?). Also in another board the is a solder excess taht tuches the adjacent chip pin (If my eyes don't fool me)

thanks, Kostas


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## zzonbi (Jul 20, 2008)

"friend you lost me here....in laymans terms was that an improvement of the Kennan board style?" I think so.

"What do you mean by the>=12V input reference? taht the board it is optimized for that voltage range?" Yep, IC takes up to 20V input voltage.

"What do you mean by the term pull up?" It means a 'hanging in the air' input
voltage is pulled up to a higher voltage so as to see a logical 1 signal. It could be pulled down as well, eg by connecting to ground.

"also R1&R2 are connected but doesn't things change if the led input wire is placed between them? (are they in a series or parallel?)." Things are already changed by C1. They are neither series, nor parallel.

"Also in another board the is a solder excess taht tuches the adjacent chip pin (If my eyes don't fool me)" Eyes could fool, better take a multimeter and verify. And be sure you press the probes rather hard to make a good contact.

Looks like they listened and finnaly put that RC snubber. I agree with you uk_caver, this new version looks better. Perhaps they didn't shunt R6 to make it easier to add an R7 such as the chip would disable when batteries discharge lower than a desired level (the supposed role of the missing IC). Your version is more probable though. Now if only my Kennan would work, because I don't think they intend to send me a replacement :-/

Do your Kennans make a hissing sound?


----------



## uk_caver (Jul 20, 2008)

kosPap said:


> friend you lost me here....in laymans terms was that an improvement of the Kennan board style? What do you mean by the*>=12V input* reference? taht the board it is optimized for that voltage range? What do you mean by the term *pull up*?


I'm sorry for the length of this post, but I don't find it easy to describe things concisely. (and I hope space forgives my modification of the excellent diagram from post #53)

The 8-pin chip on the board (the PT4105E) has an input called 'CE' (chip enable), which is used to turn the chip on and off. If this pin is pulled low (eg connected to the 0V input or similar, that switches the chip off. If this pin is connected to the positive supply, it turns the chip on.

The PT4105 datasheet is at:
www.ihonlynorth.com/forums/attachments/fabrication/1696d1210005394-led-tech-4x4s-*pt4105e*.pdf

In the *original* Kennan boards (which were sold last year), this CE input pin was connected to the positive voltage supply to the chip (ie the input from the battery), so the chip was always on.

In the *newer* Kennan boards (sold recently, and as described in post #53), the combination of IC1 and R4, R5, and R7 turned the PT4105 off if the battery voltage dropped below a certain voltage.

In the board you were asking about, a resistor was used to 'pull up' the CE input (effectively, to make the voltage at the CE pin high enough to keep it permanently on, whatever the battery voltage was, similar to the way the original boards work.

What is an improvement depends a lot on how someone plans to power the circuit.
In some situations, having a low-voltage shutdown (like the New Kennan boards) can be good (basically, if you're running off Li-Ion cells, and the shutdown voltage is appropriate to save the cells from overdischarge).

However, in other situations, having a shutdown voltage can be either a problem if it's set too high for the supply you're using (such as 4xNiMH?), or meaningless if it's set too low. For example, a shutdown voltage of 6V wouldn't protect your cells if you were running off 4xLi-Ion cells in series.
In those situations, the old Kennan or the board you showed a picture of would be better, or at least as good.

Page 6 of the datasheet for the PT4015 suggests that if the input voltage is 12 Volts or above, a certain resistor and capacitor in series are connected across the input to help keep the circuit stable. The datasheet suggests that that extra resistor+capacitor is is probably not necessary if running from batteries, which is presumably why the Kennan boards don't include them.
However, on the board you have, this resistor and capacitor are added.

This could be useful if the board is going to be run from some kind of power supply other than batteries, such as if running LEDs off a 12-18V power supply powered from AC mains, and it isn't going to cause any problem or waste of power even if the board *is* run from batteries.

The circuit diagram for the circuit you showed seems to be:




You can compare this with the one made by space in post #53, which I used to generate this diagram from.



kosPap said:


> also R1&R2 are connected but doesn't things change if the led input wire is placed between them? (are they in a series or parallel?). Also in another board the is a solder excess taht tuches the adjacent chip pin (If my eyes don't fool me)



R1 and R2 are already connected, so there's no problem if the solder for the output wire flows and touches both R1 and R2, since that isn't making any new connection between components on the board.

Looking at the datasheet, there are *some* PT4105 circuits where the connection between R1 and pin 8 of the 4105 needs to use a resistor - these circuits are where some dimming control is being used.

However, if the PT4105 is running at a fixed output, a direct connection between the 'output' end of R1 and pin 8 of the PT4105 can be used. In that situation, it doesn't matter if some solder *does* bridge across from the R1/R2 connection to pin 8 of the PT4105, since that will only result in R2 being shorted out, which won't affect operation.


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## kosPap (Jul 20, 2008)

Thanks for the explanation. Somehow I got it...and i can safely & efficiently use 6V with this

Now, would you prefer this flavor over any other version of the board???


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## uk_caver (Jul 20, 2008)

kosPap said:


> Now, would you prefer this flavor over any other version of the board???


Personally, it doesn't matter too much me.
Given the way I use them, I don't need the low voltage cutoff in any applications and though I might sometimes have a use for the the RC circuit, that is only in applications where I have plenty of space to add it externally to the board if necessary.

So far, in various projects, I've been using Kennan boards I bought last year, (like the first picture in post #29), which didn't even have a place to put the low-voltage cutoff chip.

I just looked in my component store and checked out the newer Kennan boards I bought a few months ago, and they're just like the boards you showed a picture of, without IC1, and with an RC circuit on the input.


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## zzonbi (Jul 20, 2008)

This latest version does not have an external circuit for low voltage shut-down. Both R6 and R2 are redundant, they can be shorted.
I am wondering how this circuit can be modified to get a constant voltage supply. Perhaps getting the feedback from a voltage divider only would do that?


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## CM (Aug 11, 2008)

Good thread. wish I found this earlier.


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## 2xTrinity (Aug 12, 2008)

zzonbi said:


> This latest version does not have an external circuit for low voltage shut-down. Both R6 and R2 are redundant, they can be shorted.
> I am wondering how this circuit can be modified to get a constant voltage supply. Perhaps getting the feedback from a voltage divider only would do that?


Basically what this chip does is behave like a 200mV regulator. It tries to ensure that the voltage seen at pin 8 (FB) is 200mV. There is a sense resistor between the LED negative, and ground, to convert the output current into a reference voltage. The latest Kennans delivered have had a 0.2 ohm resistor as the sense. There will be 200mV dropped across that sense resistor when current trhough the LED is one amp, thus, it behaves like a 1 amp current regulator. Increasing the sense resistor value will decrease the regulated output current.

If you ground your LED (or whatever you're driving with the board) directly, and remove the sense resistor, you can wire up a voltage divider to pin 8. I'd set up a voltage divider using a 1k-ohm resistor between the feedback pin and ground, and then a 100k linear trimpot between the voltage output, and your feedback pin. This way, by adjusting the trimpot, you'll be able to achieve any voltage output you want all the way up to 20V (the max the board can handle).


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## TorchBoy (Aug 12, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



2xTrinity said:


> If you ground your LED (or whatever you're driving with the board) directly, and remove the sense resistor, you can wire up a voltage divider to pin 8. I'd set up a voltage divider using a 1k-ohm resistor between the feedback pin and ground, and then a 100k linear trimpot between the voltage output, and your feedback pin. This way, by adjusting the trimpot, you'll be able to achieve any voltage output you want all the way up to 20V (the max the board can handle).


That's not very dissimilar to the approach taken in the first "Dimming Control" diagram on page 5 of the datasheet. They still have the LED connected to ground via R2, though, which would mean for that particular arrangement VFB was never shorted to ground. I don't think there's any advantage for the LED.

Using either of those voltage divider setups, if your input voltage varied the current regulation would change, right?


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## 2xTrinity (Aug 13, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*



TorchBoy said:


> That's not very dissimilar to the approach taken in the first "Dimming Control" diagram on page 5 of the datasheet. They still have the LED connected to ground via R2, though, which would mean for that particular arrangement VFB was never shorted to ground. I don't think there's any advantage for the LED.
> 
> Using either of those voltage divider setups, if your input voltage varied the current regulation would change, right?


In the voltage divider I specified, the feeback resistor is bypassed so there is no current regulation, only voltage regulation, which is what the poster I was replying to wanted.

Using the "dimming control" on the datasheet, increasing the reference voltage in effect causes the output current to decrease linearly (I have tested the board, and yes the relationship between current out and voltage in is remarkably linear IF the feeback resistor is used). The value of the feeback resistor still determined the "maximum" output current (eg, externally applied voltage = 0). 


I haven't tested the board extensively in an open-loop setting at all (eg, LED or load directly grounded, and FB not conncted in any way to the output). But I imagine that the relationship between input voltage and output current would no longer be linear, and might even vary based on factors such as Vf shift due to heating in the LEDs etc.


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## TorchBoy (Aug 13, 2008)

*Re: Desperately looking for driver (updated Kennan driver?)*

Thanks for that clarification, 2xT. I guess I should revise what I said about advantages for the LED with R2 in there - staying in current regulation instead of voltage regulation would be an advantage in most situations.

It's good to know the board is so controllable.


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## manne (Aug 19, 2008)

The layout has been changed again:

https://www.candlepowerforums.com/posts/2576264&postcount=1

R2 and R6 is 3k on mine.
The diode has become bigger format (like first kennan) while the output capacitor is smaller.


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## cytoe (Sep 21, 2008)

Anyone use this board to power 3 x 3watt led's (cree, etc) using a 14.4 Li-ion pack? I've had 3 boards die w/in a couple of minutes of power on. The original boards worked fine. These failing boards are the new design, but not the latest. Trying to figure out if they are worth ordering again to try out. The next best option would probably be a BuckPuck...but it costs more


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## Brlux (Sep 30, 2008)

I played with the Zetex zxld1360 a while ago for the next generation of my home lighting setup. They are great little switchers, the best and worst part of them is the control pin. It can be driven with roughly a .3-2.5V DC voltage to control the brightens but the thing I didn't like is it didn't go low enough for my liking before they would just shut off. If configured with the .1 ohm sense resistor the lowest LED current I could get before they would go in to shutdown was about 200mA. If you want to go any lower then you have to use a PWM on the control pin but it has to be below 500 Hertz so in my opinion the frequency would be annoying. You could go with a higher value sense resistor like a .2 ohm and you would be able to get it down closer to 100mA and still have your 1A drive capability when feeding 2.5V on the controle pin but then you are sacraficing efficiency. They are very small 5 pin SOT-23 and a bit pricy but have a wide input range up to 30V and are very efficient. I was getting around 94% range when driving 3 rebels form 12V. Unfortunatly my project could not work with the minimum output limitations. They may still find their way in to other projects of mine down the line though.


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## jtr1962 (Sep 30, 2008)

Brlux said:


> You could go with a higher value sense resistor like a .2 ohm and you would be able to get it down closer to 100mA and still have your 1A drive capability when feeding 2.5V on the controle pin but then you are sacraficing efficiency.


You're actually not sacrificing all that much efficiency in exchange for a much greater dimming range. If you're driving 3 LEDs then your total Vf is around 10V. The 0.2 ohm sense resistor only adds 0.1V of overhead at 1 amp drive current. This decreases the efficiency by about 0.1V/10V or 1%. A small price to pay IMO. That being said, I wish the ZXLD1360 was designed maybe for 5V on the ADJ pin = 100% output. 0.25V then would allow dimming to 5% while still allowing use of an 0.1 ohm sense resistor.

If using PWM then 500 Hz shouldn't be noticeable at all to the eye although it might still give a stroboscopic effect with things like fan blades.


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## gillestugan (Nov 17, 2008)

New version again, this time a beautiful green PCB 













The R2 and R6 are now 1k. 
Seems to be running pretty cold and nice. 1.01A out before I modded it 
I did the pot mod described earlier in this thread and made some efficiency measurements when running one Q5 off 12V. Its really great, to have dimming down to a few mA. 
Here are the numbers:

0,87A 81%
0,50A 83%
0,25A 90%


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## Doh!Nut (Nov 18, 2008)

Thanks for the update

I have a few of the version 2 keenans 
Does anyone know if they can be driven in parallel to get 1400ma?

I have seen this done with two sandwich shoppe drivers.

A second question would be is it possible to wire them in a way that you could switch one off for a high/low. I ask this because I have tried it before using a double throw switch powering a buckpuck and a bucktoot. it would only run for few seconds before cutting out - I assume this was the open circuit protection cutting in because some current was flowing back through the unpowered driver. Is this likely or was it something else:shrug:

Thanks
Nick


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## Spykooo (Nov 18, 2008)

Hello Everybody! :nana:

I'm French and I don't speak English very well. 

With friends, we made MTB Light with P4 Seoul.

For regular courant I choose this component on Kaidomain.

Today I tested the assembly. It's ok, the LED ignite.

But, I mesured the exit current without LED and I find 900mA????? It's normal?

I test with beeper my welding and enter (-) LED and (-) power the beeper is ok!!!! Where is my R1? It's like I jump R1 with my welding.

Please Help!

For amateur we can see my first realisation here : http://spykooo.unblog.fr/2008/06/14/fabrication-dun-eclairage-pour-vtt/


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## uk_caver (Nov 18, 2008)

900mA is normal if your driver has an 'R200' (0.2Ohm) for R1

The PT4105E chip used on the Kennan driver has a feedback voltage of 200mV, +/- 10%. With an R200 for the current-sensing resistor R1, that gives a current of about 1 Amp, +/- 10%.

(The earlier Kennans used an R270, which gave a current of ~740mA)

Since R1 is a very small resistance a continuity tester would probably react to it the same way as it would react to a short-circuit.


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## Spykooo (Nov 18, 2008)

OK ok I'm happy for your answer!

I wanted 750mA and I have 900mA...
If I replace R1 (0.2ohm) by 0.27ohm I find 750mA?

You confirme my idea for the continuity tester.

Thanks for your help.


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## gillestugan (Nov 18, 2008)

yes, and the driver will run cooler and more efficient.


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## cytoe (Nov 19, 2008)

Can anyone confirm that this new driver revision can run 3xled from a 14.8v Li-Ion pack? Sort of lost confidence in this driver after toasting 4. Seems the last "new" design sucks.


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## 2xTrinity (Nov 19, 2008)

cytoe said:


> Can anyone confirm that this new driver revision can run 3xled from a 14.8v Li-Ion pack? Sort of lost confidence in this driver after toasting 4. Seems the last "new" design sucks.


The reason it's toasting is Kai, or whoever assembles these boards, dropped the sense resistor from ~0.25 ohm, to 0.2 ohm, effectively raising the current from 750mA to 1A. This was done to make the chip "better" and more powerful. The thing is, the PT4105 regulator chip really shouldn't be run higher than 750mA continuously as its efficincy drops and it can excessively heat up. If you replace that sense resistor, you will be fine to run any sort of setup you want.


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## cytoe (Nov 19, 2008)

Thanks for the info. Do you know where I can find these resistors? The local RadioShack doesn't seem to carry such small resistors.


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## gillestugan (Nov 19, 2008)

I'm currently running three XR-Es at 700mA on a 14.8V pack. Haven't calculated efficiency yet, but the driver runs very cold.

I didn´t change the R1 as I didn´t have any low value resistors.

Instead I put a 100k resistor from output to R2 as shown here: https://www.candlepowerforums.com/posts/2497628&postcount=85 
I kept the R2

This gives me a 700mA output.


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## uk_caver (Nov 20, 2008)

I guess the value needed for that approach depends on the value of R2 (which does change between one board revision and another) as well as the number of LEDs driven, so it would either need calculation or experimentation.


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## gillestugan (Nov 20, 2008)

Yes, you are right, I didn't think of that. R2 is 1k on my board.
One way is to adjust the current to whatever you want with a potentiometer, then measure the resistance in the potentiometer and switch the potentiometer for a fixed resistor.


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## gillestugan (Nov 25, 2008)

I want to use two boards in parallel. Is it possible to to wire the 2:nd as slave to the first one, so that when you adjust the output from the first one, you also adjust the 2:nd?

Would it work if I remove the R2 on the 2:nd board and wire the FB pin to FB on the first one?


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## kosPap (Nov 26, 2008)

hi all! In this post in another thread I have added measurements of 2 versions of this driver.

Enjoy, Kostas


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## spun (Dec 11, 2008)

another way to mod R1 if you don't have these low value resistors is of course to replace R1 with 1 ohm resistors in parallel. i'm using two in parallel to get .5 ohms which runs 3 leds in series at 330ma. see parallel resistor calculators on the web or for these just simply 1/number of resistors so 4 would be .250 which i think the original kennan had. i think it's easier to do the dimmer mod and then if you want swap the pot for the resistor of your choice as gillestugan mentioned but this is another method.


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## tobyjmack (Jan 7, 2009)

apologies for resurrecting an old thread but I came across this discussion when trying to find ideas for drivers and the mention of the PT4105 got me curious if dealextreme did any equivelent.

Well, after a bit of poking around I can say that that the DX SKU07425 is based on the PT4105.
I've buzzed out the board and it is identical to the data sheet example circuit except for the following-
1) It has two 0.5R resistors in parallel for the sense resistor (giving 0.25R and 800mA drive rather than the 1A quoted by DX....)
2) it has a 10k resistor from the sense to the feedback pin
3) it has a piggy back microcontroller to give the 5 modes. 

As the basic circuit is as per the data sheet I can't see why it won't work to 18V rather than the 8.4V quoted. The only possible problem is the piggyback board which I haven't checked thoroughly. However, there is 5V going to the IC so I think it is regulated so the only question is whether the regulator will cope with 18V. Most will....
I've taken it up to 12V when driving a single Q5 and it still works fine 

Hopefully that might be of help to someone?

Toby


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## italianboy (Jan 19, 2009)

I'm new of this forum, so first, hello to everybody!
I'm posting here because I have a problem with this driver. I've bought it from KD, but I've got a new board, different from all the previous here and also from the one shown on the KD site, so I don't know where to solder the led wires.
This is the image:





I'm quite sure the "+" should go under the inductor, where there is the "+", but should I solder the "- " (looking at this image) over the R1, under the R1, or elsewhere? 
Thank you all in advance!

P.S. I don't want to fry this board because I've waited over a month and I have only one (the one I have to use...).


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## space (Jan 19, 2009)

The AX 2002 are simular to the PT4105 (used on previous model) in the way it operates, but the pinout is different. The AX2002 is a bit more powerfull and can handle abit higher input voltage. (Can handle abit higher swithcing current and up to 23V input voltage compared to 18V for the PT4105.) I can't see the R1-label you are reffering to, but I guess you are talking about the R220-resistor. The "-" should be conected to witch ever side of the R220-resistor that is not directly connected to "-" for the board. From your picture it seems like that is the "south-end".


space


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## uk_caver (Jan 19, 2009)

duplicate post - removed


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## gillestugan (Jan 19, 2009)

Data sheet can be found here.
Would it be possible to regulate output by using resistors as voltage dividers for the FB bin in the same way as on the PT4150?

Will also be interesting to see what efficiency you get and how high output it can manage. (2A in the data sheet, but that is just the AX2002, not the rest of the components.)


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## uk_caver (Jan 20, 2009)

The AX2002 datasheet does mention pins 5&6 are a thermal path to the internal die, so it might be possible to arrange for some extra heat dissipation for high current usage.


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## italianboy (Jan 20, 2009)

Thank you very much, I've tried to do that and, from a very quick test on a single 18650 (but I'll use a 6v lead-acid) it looks to be working correctly.
P.S. Thank you also for all the other useful information on this forum!


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## Spykooo (Jan 21, 2009)

Hello from Frenchees!!!!

I have a problem with my KD régular!

For 3 regulars i have 800mA : Good!

For 6 regulars i have 400mA : No good! But why i have 400mA?

My last regular do : Psssssssssssshit!:laughing:


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## uk_caver (Jan 21, 2009)

Are all the drivers the same?
Do they all have an 'R220' or 'R270'?

What input voltage are you using?
How many LEDs are you driving, and what is the total Vf for your LEDs?


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## Spykooo (Jan 22, 2009)

uk_caver said:


> Are all the drivers the same?
> *Yes.*
> 
> Do they all have an 'R220' or 'R270'?
> ...



Thanks!


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## gillestugan (Jan 22, 2009)

I received the AX2002 version today and will do some efficiency measurements. 

Does anyone have a request for a specific condition? (Vin,Vout,Iout)


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## gillestugan (Jan 22, 2009)

Have done some testing now and I like it! It is very tough. As you can see in the graph I was able to push it to 2,5A. Then it was shutdown by the thermal protection. When I turned it on again it worked like before. This happened many times during the 2A+ tests, until I put an extra heatsink on it. It wasn't really stable over 2. Had it on 2.2A for 5 min, but then it got too hot and shut down.

The test setup:
Old computer PSU 
Mulimeters (Vin, Vout,Iin,Iout)
8A rectifier diodes as load. (didn't want to risk my MC-E)
Modded driver with dimming, lower R2 and a small heatsink soldered to pin 5 and 6 as suggested bu uk_caver

As you can see there are some variations, this can be because of:
I used the 20A socket on the multimeters and they are far from accurate, but both mulimeters are axectly the same and gives the same value of a current, so it shouldn't influence efficiency calculation too much.
The diodes got hot and VF changed slightly, this is of course measured and in calculation.
The dimming method used is not very temperature stable.
-A real amateur test 










Here are some pictures of the board:
To do the dimming mod you have to cut one of the tracks on the board. (see picture)
Then solder A potentiometer and a resistor as shown in picture.

If you want higher output than 1A you need to change R2 to a lower value. Look in the data sheet for resistor values.


















Heatsink with ugly soldering, sorry


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## Stage X Tuning (Jan 22, 2009)

Well i have looked to all ends to find a good driver for the SSC P7 and cant, so i found a IC that will do a Max of 3A with 2.5V-18V in and a 89% efficiency from .25A to 3A at 5Vin and 3.3Vout. per paper calculations, still not tested. All that and you only have to use 8 to 12 or so parts if you want to use the ICs over-current protection, and short circuit protection. im hoping to have a prototype working soon


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## uk_caver (Jan 22, 2009)

Nice work, gillestugan.

I may order a few more Kennans myself. I've been building a few smart chargers for 3.6V NiMH packs using the PT4015 Kennans running at 750mA, but it would be nice to be able to make some faster (~1.5A) chargers.

It looks like the soldering is to pins 7&8 (2xVss), rather than 5&6.


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## gillestugan (Jan 22, 2009)

uk_caver said:


> It looks like the soldering is to pins 7&8 (2xVss), rather than 5&6.


 You're right! Haha, maybe I should do one more test with the heatsink connected to the right pins. It did get pretty hot, but I assume most of the heat came from the top of the chip. Thanks


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## uk_caver (Jan 22, 2009)

I guess heatsinking the chip top probably *is* doing a lot of the work - the pin 5&6 thing is most applicable to a board designer who has onboard copper to use, but who won't want to bother with glue-on heatsinks.

Did you measure the current with the stock R220 for R2? Is it the expected ~1.14A, or something else?

I just ordered 5 boards - here's hoping they come with AX2002s


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## spencer (Jan 22, 2009)

Where are these on KD's site? I did a search for kennan but didn't come up with anything. I know I've seen them before but I can't find them now.


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## gillestugan (Jan 22, 2009)

Spencer: 
They used to name their items and this one got the name "kennan". Now they only use numbers. Boring but more practical. You can find it here.

uk_caver:
Whe I first hooked it up it was exactly 1,00A (!). Then it varied between 0,97 and 1,03 depending on input voltage and probably also temperature.


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## Hîlon (Mar 3, 2009)

Hello I’m new to this board.

I just received a few drivers of the AX2002 version and I would like to use the dimming mod for running one Cree R2 LED between 100mA and 500mA. I’m going to cut one of the tracks on the board as shown in the picture. The problem is that I don’t know where to connect the potentiometer and the resistor that are apparently needed. 


> Then solder A potentiometer and a resistor as shown in picture.


 Maybe I’m just overlooking something but I can’t see an additional potentiometer on both pictures. The only thing I see is a resistor hiding behind the copper heatsink. Where do I have to solder both parts and what resistance do they have to have? 

Thank you very much in advance!

Olaf


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## gillestugan (Mar 3, 2009)

There was apparently something wrong at imageshack and the picture. I have now rehosted the image and it should work fine.

Resistor values cant be calculated without knowing the exact Vf of your led at those levels. 

You can set maximum to 500 mA either by replacing R2 with a higher value (calculated with the formula in the datasheet) or use the right resistor values in the dimming mod.

Easiest to do it is to measure the resistance on the potentiometer when you have 500mA. Then put a fixed resistor with the same value in series with the potentiometer and you will have a new maximum at 500mA.

You can then measure the potentiometer resistance at 100mA and replace the potentiometer with one that has the measured value. You will then have a range between 100mA and 500mA

An alternative is to use a zener diode as voltage reference. Any zener with lower value than battery voltage will do. If so I can calculate resistor values for you.

you will then need one zener diode, two fixed resistors and one potentiometer. The dimming will then not be dependent on output voltage and will work the same regardless of how many leds you put i series on the output. (the board can easily handle 6 in series)


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## Hîlon (Mar 3, 2009)

Thank you very much for the information! I guess I’ll go with the right resistor values in the dimming mod for now and do a little testing on how well it is working in terms of efficiency with different battery solutions over the voltage drop of the cells. 
Again, thank you very much for your help. 

Olaf


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## uk_caver (Mar 3, 2009)

My AX2002 boards just arrived, and they look like the ones posted above.

I was wondering if anyone knew what was happening with the COMP pin (pin 3)
On the datasheets, it's shown as having an 11K res and 0.1uF cap in parallel to ground fotr a single-diode load (and 20K/0.1uF for 3-dioide loads) but on the KD boards, it has a 100K res and some capacitor to ground, but also a diode and series 4K7 res leading to inductor +ve (pins 5&6)

That diode/resistor combination doesn't seem to be shown on the datasheets, but I'm assuming that it's there to try and automatically adjust the average resistance from the COMP pin to ground based on the duty cycle.

Would anyone have any idea if I'd be better off removing the diode/resistor and replacing the 100K res with a smaller one, if I know what my input/output voltages are going to be?


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## gillestugan (Mar 3, 2009)

uk_caver said:


> That diode/resistor combination doesn't seem to be shown on the datasheets



Are we looking at the same datasheet? 

Isn't it the diode and resistor in the circle directly under the chip in the datasheet schematics? marked "option"
It says "The option circuit for compensation is connecting R4 and a
4148 diode to Vout. In order to protect short circuit and thermal shutdown release for LED." It probably takes some power, but I have not measured voltage over the resistor, so I dont know how much power would be saved from removing it. I have tried both short circuit and thermal overload, and those function very well 

I also dont see a 11k resistor anywhere in the datasheet. Only 100k. Same as used on the board.
It says "100KΩ for all condition" so I assume there is nothing to gain by changing it.


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## uk_caver (Mar 3, 2009)

gillestugan said:


> Are we looking at the same datasheet?


It seems not - I was looking at the Axelite datasheet I found when the AX2002 was first mentioned in posts 128/129.
It's marked "Rev 1.0 Oct 26 2007"

It doesn't show the resistor+diode in the any diagrams, and all it says about the COMP pin is 
*Compensation
The COMP pin connects C3 and R3, C3 use 0.1uF in all condition. R3 use 11kΩ at
Duty on <60%, and use 20kΩ at Duty on above 60%.
*​


gillestugan said:


> I also dont see a 11k resistor anywhere in the datasheet. Only 100k. Same as used on the board.
> It says "100KΩ for all condition" so I assume there is nothing to gain by changing it.


That certainly squares with the KD circuit board. Obviously they must have changed things somewhat between v1.0 and the v1.2 you linked to (which I just downloaded).

That also explains the capacitor to ground from the enable pin on the KD board - on the v1.0 datasheet, it wasn't there - just the 100K pullup.

Thanks for clearing that up.


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## brighter-lights (Mar 27, 2009)

Can anybody help me to enable this driver for low voltage cut off? 

I want to set it to cut off @ 9.5v (using 3 cell lipo's) 

I know that on the previous versions one could enable this function... but can it be done on this latest version? I can't find any info in the datasheet. 

Thank you very much 
Jo


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## uk_caver (Mar 27, 2009)

On the previous versions that had a cutoff, it was done by using an extra chip to detect the voltage dropping, which drove the chip-enable input on the main driver chip.


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## gillestugan (Mar 27, 2009)

uk_caver said:


> On the previous versions that had a cutoff, it was done by using an extra chip to detect the voltage dropping, which drove the chip-enable input on the main driver chip.



Yes, you have to add you own external voltage sensing chip to the driver. It can be done as the AX2002 also have an enable pin. 

It may also be possible to use only a zener diode and a resistor connected to the enable pin, but this is probably not very accurate. According to the data sheet you need somewhere between 0,3 and 2,5V to enable the chip, The actual enable voltage should be able to measure, so you can add a zener with a value just below battery cutoff voltage minus enable voltage. It probably not very stable anyway. Im just speculating and have not tested it. Only tested the enable pin.


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## uk_caver (Mar 27, 2009)

Even if the voltage could be selected accurately enough, there might be some odd behaviour with a cutoff circuit that slowly drifted to the point where the chip-enable signal was turned off.

I'd have thought that a cutoff chip would have some hysteresis built-in to try and avoid oscillation, turning off the driver, then having the battery recover and turn the driver back on again.


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## gillestugan (Mar 27, 2009)

you're right. 
I just tested one. Not for battery recovery oscillation but how it behaves between 0,3 and 2,5V. Not good...
It start to flicker when voltage is below 2,5V Then flickers more and more down to 1,1V where it shuts off completely.
Not really the the kind of voltage monitoring you want. 

Better to use a real voltage monitoring circuit with enable voltage a little higher than cutoff voltage.


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## zzonbi (May 10, 2009)

"For 3 regulars i have 800mA : Good!

For 6 regulars i have 400mA : No good! But why i have 400mA?"

Measure the voltage across R220, it should be 250mV. If so, maybe something is wrong with those resistors.

I transplanted an R200 resistor from my defunct PT4105 driver (death by ringing) and the current bumped up a bit, from 1080 to 1200mA. The new AX2002 seems more robust indeed, even if it lacks the low current mode bonus, it actually superseded the PT4105.

Does anyone know where to get such low value SMD resistors online, with cheap/free shipping?


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## rionsumisu (Jun 10, 2009)

space said:


> ...snip... I can't see the R1-label you are reffering to, but I guess you are talking about the R220-resistor. The "-" should be conected to witch ever side of the R220-resistor that is not directly connected to "-" for the board. From your picture it seems like that is the "south-end".space



I found this reply to italianboy's query a bit hard to comprehend until I'd spent a fair time looking at everything I could find and re-reading. Hopefully I can clarify this for others: "-" for the board are all the many bits connected to "ground" (many components, if you take as an example the circuits on the AX2002 spec sheet) and this is found in a ring of circuit copper surrounding most of the new Kennan/002982 board from KD. If you connect the negative side of your LEDs to this you get an unregulated(?) 1.5A into 2 Crees from 12V source, or 2.5A into one Cree (it squeals that it's about to die shortly when you do this - so don't). So pick up the other, inner (ie: not touching the outer rim of circuit), end of the 220ohm resistor that is adjacent to the empty R2 spot on the board. It's okay to join the inner side of the 220ohm resistor and the nearest solder pad for the vacant R2 with a solder blob and your piece of wire; just don't contact the outer rim circuit, or the other solder pad for R2 that is further away from the 220ohm resistor or you'll get the unregulated(?) 1.5A.

I also found that putting 5ohm resistor between the 220ohm resistor and the LEDs reduced the current to 700mA (very little heat generated  when driving two Crees from a 12V NiMH pack, but was still 1A when only one cree used. 10ohm resisor cut it back to 700mA for a single cree.

Hope this is some use (my first post here).


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## tamen00 (Jun 12, 2009)

Excellent information and very clear instructions. I have a question though... if you add the resistor to reduce the current to 700mah between the R220 and the - on the LED, does that decrease efficiency? Is the resistor just eating up the other 300 mah? (total electronics newbie... but trying to learn!)

Thanks


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## TorchBoy (Jun 12, 2009)

:welcome:

For a start, mAh (note capital A) is capacity and you mean current, which is mA, for milliamps (or A for amps).

No, changing the set resistor doesn't in itself change efficiency, because the same reference voltage will still be across that resistor, whatever its total size is changed to, and the regulator sorts out what the current should be from that. The efficiency is calculated by power out / power in. Power = current x volts.

In practice however there might be a change in efficiency due to the regulator working more efficiently at a different current. The spec sheet indicates the AX2002 works less efficiently at currents under 1 A. (The voltage drop across the LED will also decrease which might also drop the efficiency, but the efficacy - lumens per watt - of the LED will increase.)


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## tamen00 (Jun 12, 2009)

Thanks for the information and the welcome to CPF board. I have been lurkinghere for a long time and have been playing with these driver boards a bit... and just trying to see what way is the best to use them... use a resistor to set output to 5-600 mA (see, I am learning already lol) and run 3 XPES series off 11.1v... or set the current at 1500 mA and run the XPE's parallel off 7.4v. (I have both battery packs... just trying to determine a cheap way to use the packs...)


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## ambientmind (Jun 30, 2009)

I've been looking through this thread, and I'm a little lost with my quest for an answer. I'm just looking to mod this board so it can output about 350-450mA. What size and where do I need to solder the resistor? Thanks!


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## uk_caver (Jun 30, 2009)

For the newer (AX2002) version of the board, for 400mA, you'd want a current-sense resistor of 0R625, replacing the 0R22 resistor (marked 'R220')

Looking at my electronics supplier, resistors in 0805 size are available in values of 0R56, 0R62 and 0R68, which would give theoretical output currents of 446mA, 403mA, and 367mA respectively.


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## bshanahan14rulz (Jul 27, 2009)

I don't understand how you search for these boards, or why they are called kennan. I have a 17mm driver board that needs replacing soon (it smells like burning electronics) and am thinking that this board, with all of your research, seems to be the most fun. So, from what I understand, it is a generic board from KD or DX that provides CC (as opposed to a controller board or a buck/dd board)


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## TorchBoy (Jul 28, 2009)

Kennan was a constant current driver board from KD (back in the days when their site worked) that scored three out of three: It was inexpensive, efficient, and versatile - it accepted 5-18 V in, and output a constant current for 1 to 3 LEDs. It claimed a lot, did what it claimed, and developed a fan following because of it. It got the name Kennan because KD and DX used to make up pseudo-random names for all their products back then.


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## bshanahan14rulz (Jul 29, 2009)

hah, they just made up names? So this was an old board that has since been replaced by less efficient but higher current boards? Like, is it not available anywhere anymore? seems like a backwards step for batteries, though I wouldn't care so much if it were for a wired application...


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## Justin Case (Jul 29, 2009)

I don't know about the efficiency of the original Kennan, but this new KD board based on the AX2002 seems quite efficient.

I am using a modified version to drive a 2S2P MC-E at ~700mA per core. The board uses a sense resistor setup to deliver 1445mA (nominal, based on the output current equation in the AX2002 datasheet) out.

I didn't measure actual Vf or Iout, but on my bench power supply, the driver requires about 10W of power in when running in regulation. If we assume Vf~6.5V and Iout~1.4A, then Pout~9.1W, or about 90% efficiency.

The driver runs in full regulation starting at about 7.0V, which seems quite good in terms of voltage overhead.

One caution. It appears that the inductor may be undersized for this higher current output application. Above 12V for Vin, the driver becomes unstable and Pin starts to behave oddly (it isn't 10W anymore -- it fluctuates from about 4W to 8W). To run above 12V Vin, the inductor should be 33 uH or so. If the board I have uses the same 22 uH inductor that is shown on the KD web site, then that could explain the instability. Unfortunately, the inductor on my board is scrubbed of all markings.


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## Capo_au (Aug 10, 2009)

Just received two of the AX2002's in the mail today. Having not had a chance to play with them yet I can only comment on the shipping and appearance.

It took exactly 2 weeks from time of order with 8 of those being business days. Packaging was also more than adequate. The inductor also appears to have had no markings or the markings have been removed the same as the post above.

I will be sure to post some pic's when i get the dimmer mod up and running.

-Capo


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## Capo_au (Aug 20, 2009)

Well I finally got the time to have a play with my new AX2002's. Did the dimmer switch mod to a pair of the drivers and connected them to 4 ER-E's, 2 a pc. 

Works like a charm, the only problem I have encounter is a slight fluctuation in the current in the first 30 seconds or so of switch on. My guess is the battery voltage is dropping to quickly in that first 30 seconds or so for the drivers to be able to keep up.

Now some photos for good measure. 

I used a 10kOhm dual rotary pot to control the current to both drivers at once. I only wanted a 1A max current so I have put a 1kOhm resistor (not shown) in series with the pot. With out the 1K resistor it it would dial all the way up to about 1.45A where everything got very hot very fast even with large heat sinks on the LED's.






A close up of the mod'ed AX2002. Green wires are for the pot, red is + led black is negative. The red and black wires both came with the driver. Note:Its hard to tell in the photo but none of the soldered connections are contacting the outer ring.





Simultaneous readings of the current output from both drivers. Close enough that i cant tell the difference by looking at them.





Many thanks to all the previous posters, all the info came in very handy.

-Capo


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## Capo_au (Sep 7, 2009)

In the post above I dimmed the two drivers at once using a "dual rotary" pot. This means that each drive is essential dimmed by a different pot, so to speak.

Does anyone know if it would be damaging if i was to use a single rotary pot to dim both drivers at once? They would be powered off the same power source but driving separate led's.

Thanks. lovecpf


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## gillestugan (Sep 7, 2009)

Hi, it wont be damaging, but unfortunately it doesn't work. You will never get the same level on both drivers. When one of the drivers goes high, it will cause the other one to go low, so they will never be in balance. (as long as the pot is connected to output. Maximum level is still restricted by the sense resistor, so it wont damage the driver or led.
It may be possible to make it work if you use a diodes to block current going both ways between the circuits, but I haven't tried this.

You may be able to calibrate the output by changing the value of the fixed resistor of one of the circuits, but this is probably not worth it. As you say, it is not possible to perceive the difference in brightness.


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## Capo_au (Sep 7, 2009)

> Maximum level is still restricted by the sense resistor, so it wont damage the driver or led.



Good to hear, that was my major concern.



> It may be possible to make it work if you use a diodes to block current going both ways between the circuits, but I haven't tried this.



I will give this a try one day when i get the time and post my results.

Thanks for the help :twothumbs


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## tobyjmack (Sep 14, 2009)

*has anyone used the enable pin on the AX2002*

Hopefully not deviating too far from the original thread but has anyone used the enable pin on the Kennan board?

According to the AX2002 datasheet it should turn on with anything over 2V. I am finding that 3.3V (output of a PIC) only turns it partially on. I get only about 100 to 150mV on the sense pin and a dim light. Reconnecting the on board 100K pullup and it works fine with 250mV on the sense pin.

Has anyone else done anything similar, I've testing it on two boards so I am pretty sure I am right but it would be good to get confirmation I am not doing something silly!

Toby


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## uk_caver (Sep 14, 2009)

I've driven the AX2002 Kennans from PICs, leaving the pullup resistor in place, and pulling the enable pin to ground via a MOSFET when I want to disable the chip.

However, I have been using them as cheap buck drivers in smart battery chargers, so I haven't needed rapid on/off performance (as would be needed for PWM control for a lighting application).

When you're trying to drive with a PIC, how are you making a connection - through some resistor, or a direct connection?
The voltage readings you were getting do seem a little odd at first sight.


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## tobyjmack (Sep 14, 2009)

I've used it with both direct connection and with a 47k series resistor, both with the 100k onboard pullup removed.

I've also tested it with the 100k pullup in place and just probed the enable pin with a high output from the PIC (3.3V). When the pic line is disconnected then the driver is on full, when connected it goes to half brightness. So it seems pretty conclusive that it needs greater than 3.3V to turn it on.

Using a fet to pull the enable low to turn it off does look the simplest option. The downside is an extra 100uA current draw when off but that will not be a major problem as long as I don't leave it connected for months.

A shame if this is the case but it is not the end of the world.

Toby


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## tobyjmack (Sep 16, 2009)

a quick update in case if affects anyone else.
I have put the on board pullup back on the enable and used a transistor from the pic to pull that low (as suggested by uk caver).
So far at least it is behaving itself properly. :thumbsup:

It is an extra component and 100uA on the off current but I can live with that.

Toby


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## Capo_au (Sep 16, 2009)

Thanks for the info tobyjmack.

Any chance you could post a simple schematic, or even just a few photos?

I'm considering doing something similar but experience in electronic components is limited. So any extra info would be great.

Thanks!


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## tobyjmack (Sep 17, 2009)

Pics and schematic are posted here.... http://forums.mtbr.com/showthread.php?t=554555

Note that the picture of the board does not have the transistor in the enable line.

It was more hacked together rather than properly designed so it could be improved (eg filtering the battery monitor, reducing standby current) but it works ok.

Toby


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## Capo_au (Sep 17, 2009)

Thanks for the link, thats just the info i have been looking for.

-Capo


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## Tobias Bossert (Oct 10, 2009)

*Does somebody still have old Kennan2 lying around?*

I have an application using analogue dimmed driver boards in the range 30mA to 700mA for a single LED load and supply voltage starting at about 3.5V.

Kennan2 was optimized for that! But it is sold out at Kaidomain and replaced by Kennan3, which is much more powerfull for currents above 1000mA and increased input voltage range. But it is less efficient with dimmed output, especially when dimmed down below 300mA.

I'm interested in getting this old stuff. To prevent from misunderstanding, I would like to get those blue Kennans on which all components are arranged orthogonally:






In case you have such drivers and like to switch them to actual Kennan3 with AX2002, please send me a message on how many of them you can give to me. _It doesnt matter if the board has other or more components in place, it is sufficient that it has the same layout only._

I propose that I order the same amount of Kennan3 at KD in my account but under your shipping address. When you got them, you send your Kennan2 to me. Also direct payment would be possible if you want to get rid of the old stuff without replacing it. _There is also possibility that I may 'pay' with rotary switches 1 by 1. I have left about 25 rotary switches with 5 positions (30°) and 4 poles, open before close, upt to 1,5A, axis 6mm, max diameter 18mm including contacts, ITT SB16. This switches are still on the market, now from ELMA_






_Reason is, that my actual project (testdevice_3) no more requires high current switching and 2 poles but only low current switching of 1 pole. For this I use a smaller switch from Marquardt (axis 3mm, diameter 12mm) _


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## spun (Oct 25, 2009)

*rf shielding tips?*

i've got a couple of gen2 kennans running 3 leds in series each at different ma outputs. both are powered by older style wallwarts, not the switching type. running either of them cuts out a few over-the-air dtv stations. i've enclosed one circuit in an altoid box and it's not much help. the wires coming out of the altoid box are very short and the leds are maybe an inch apart on a heatsink. i am not using the altoid box as a 'ground'.


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## martinmkd2 (Nov 6, 2009)

HI, I jaust recived driver from kaidomain and it looks little different.








It looks like that extra resistor (R27) is just parallel to the "old R2" (2R2), and together makes 0,24 ohm, for 1041mA. Is this correct?

I want to make 2 mod light. One mod ~1000mA, and other ~350mA. So I was thinking to remove this two, and connect it with simple switch for one position(1041mA), and on the other position ~0.7ohm for ~350mA. Is this ok? 
It is a lot simpler that potenciometar solution, and I only need 2 mods not infinite.

One more question. Does anyone knows how much surface area does CREE R2 needs for cooling on 1000mA. Is 6300mm2 (63cm2, 9.76 in2) sufficient? Is the Aluminium Pill container from DX http://www.dealextreme.com/details.dx/sku.27551.

If not, what is the max current R2 can handle with this housing?
HI, I jaust recived driver from kaidomain and it looks little different.







It looks like that extra resistor (R27) is just parallel to the "old R2" (2R2), and together makes 0,24 ohm, for 1041mA. Is this correct?

I want to make 2 mod light. One mod ~1000mA, and other ~350mA. So I was thinking to remove this two, and connect it with simple switch for one position(1041mA), and on the other position ~0.7ohm for ~350mA. Is this ok? 
It is a lot simpler that potenciometar solution, and I only need 2 mods not infinite.

One more question. Does anyone knows how much surface area does CREE R2 needs for cooling on 1000mA. Is 6300mm2 (63cm2, 9.76 in2) sufficient? Is the Aluminium Pill container from DX http://www.dealextreme.com/details.dx/sku.27551.

If not, what is the max current R2 can handle with this housing?
Thanks


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## TorchBoy (Nov 6, 2009)

FWIW my board has just a single 0.22 ohm resistor where you have a 2.2 ohm resistor. Where your 0.27 ohm resistor is located, my board is marked R2, but you have more visible board markings than mine does. Maybe all mine are under the components. It looks like your inductor has suffered some damage.

Switching different resistances there is fine. And you mean "potentiometer".

If you're really worried about cooling, download Cree's thermal management PDF and have a read.


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## uk_caver (Nov 6, 2009)

TorchBoy said:


> It looks like your inductor has suffered some damage.


I seem to get a few arrive like that.
Glueing the fragments from the envelope back into place seems to work OK.
It's not as if the ferrite scraps have to be in perfect contact with the main piece, just occupying the right position in space.


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## martinmkd2 (Nov 6, 2009)

Those scraps are ferrite? I was thinking is just plastic.
So you think is not going to work properly without the scrap ferrite?

That is correct "Potentiometer", not "potenciometar" .
Sorry about my poor English.


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## gillestugan (Nov 7, 2009)

regarding the potentimeter solutin: you can easily switch the potentiometer to ordinary resistors an chose fixed currents with a switch the same way.

You get lower efficiency by using a higher R2 value but it may be easier and will regulate current independent of output voltage.


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## spun (Dec 3, 2009)

*rf interference II*

the new kai kennan solved my rf dtv problem. tried a bunch of things with the older gen kennans and no go. read of others using the PT4105 boards having rf problems with their cars which many people target this chip for because of its 12v+ handling. one said it cut out their radio channels and another said it disrupted their door locking fob. the only solution i read about was large low esr caps across the input and output. thanks gillestugan for the thorough info on the new dimmer mod, works great. and yes, when you unwrap a kennan from kai do it over white paper so you catch any broken inductor pieces. superglue works for me.


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## Bronx68 (Feb 10, 2010)

I am also looking for led driver. Prefer a completed assembly but would consider a kit or example design.

Buck configuration
High side current sense so I can have a common ground cathode with other
drivers.
1 amp max current
DC input 6 to 32 volts
Output voltage to about 2 volts less than DC input
Analog and pwm dimming on same pin if possible
Output short circuit protection up to 15 seconds
Very much prefer external FET switch from main controller
Max current trim


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## TorchBoy (Feb 11, 2010)

Bronx68 said:


> High side current sense so I can have a common ground cathode with other
> drivers.


Good luck.


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## KevinL (Oct 18, 2010)

Just bought one today. Wanted to reconfirm; on the bottom of the driver, the center is battery + and the ring is battery - ? I noticed someone's picture showing a very different wiring topology (driver being wired like a resistor in between LEDs!)

I'm using the standard topology, one set of connections for batt + and batt - and a separate set for LED + and LED -.


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## VegasF6 (Apr 14, 2011)

I am wanting to place an order for about 30 of these from DX. Before I do, can anyone confirm any changes lately? One forum report claims they may not have the AX2002 IC anymore. Posted by Desolder Nov 2010.
*http://www.dealextreme.com/forums/Forums.dx/Forum.26110~threadid.755890 
Under the thread "old batch was better." 
I suppose I could order a few as a sample and then place a follow up order, but that is so cumbersome, and still no guarantee. 
I still have some of these that are clearly marked ax2002, the attempt to scratch out the id was very, shall we say half hearted. I am not sure how to tell if I order more if they are the YB1682 IC mentioned. They are both the same package but the pin configuration is completely different....
*


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## VegasF6 (Apr 15, 2011)

To reply to my own bump, this looks significant:
http://forum.fonarevka.ru/showthread.php?p=30908&language=en
Why is it that when the Chinese retailer actually manages to do something right, he can't leave it alone?

Hmm. Perhaps if I read all the way through first. It states that driver came from MCE WF-502B flashlight sku 44270. (Hey I think I might have that light clunking around somewhere)
Hopefully, it isn't indicitive of changes to so called "kennan" update, sku 26110


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## Microa (Apr 15, 2011)

YB1682 is a 2A 380KHz Buck DC/DC Converter IC which is not the same type of IC like AX2002 designed specially of LED driver. If I were you, I wouldn't buy it.


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## HooNz (Apr 15, 2011)

Off topic but i felt as waste to start a new thread just for this :fail:
Could anyone figure out this ic number as it is very hard to read and might be more familiar to the experienced eye , it is either 

358 in the top rh corner then- 
either ez948a or e798a or 794a i have tried all the combinations but no luck.

It appears to be a low/mid power function that outputs to the main driver ic , a Td1410 to pin 5 which is very similar to the AX2002 (from pin 3 of this ic?) , i am trying to disable the "mid" at turn on.

Any assistance would be good , another few hours of poking around with a multimeter trying to figure out how it works might put me away! 

Paul


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## HooNz (Apr 16, 2011)

HooNz said:


> Off topic but i felt as waste to start a new thread just for this :fail:
> Could anyone figure out this ic number as it is very hard to read and might be more familiar to the experienced eye , it is either
> 
> 358 in the top rh corner then-
> ...



Not that anyone has , but the issue is resolved(as far as info is concerned) , the unmarked ic before the ez one has embedded functions in it so that is the main culprit , not the ez.
Paul


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## Microa (Jun 22, 2011)

The AX2002 has an elder brother,AX2003,which can be driven at 3A. My driver was set at 2.5A.


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## Roger555 (Oct 26, 2011)

^ what driver did you mod???


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## Microa (Oct 27, 2011)

That was a home made driver. Basically, it was the same design as DX's driver which only modified the IC to AX2003, 3A rated diode and bigger size inductor to handle the higher current.


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## Justin Case (Oct 27, 2011)

That's a big diode -- from ON Semi? I've had good success with the Toshiba CMS04 5A-rated Schottky diode. The CMS04 case is nominally 3.8mm long x 2.4mm wide. it also fits within the existing soldering footprint of the usual AX2002 boards. Assuming an ON Semi B34 diode, your diode is nominally 6.86mm x 5.84mm. The width seems like it might make for a tight fit on a 17mm board. What is your board diam? It looks bigger than 17mm (20mm?).


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## Microa (Oct 27, 2011)

The diameter of the board is 22mm. The diode size is SMC. Of course, you can replace it by the SMA size diode such as CMS04. I made this driver for testing and I had the diode on hand in my component boxes. The driver was quite hot when it was driven at 2.5A. I made some metal filled viases conducting the heat to the bottom layer as heat sink or thermal contact. It is a very reliable driving IC indeed.

The new home of the driver


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## Roger555 (Nov 1, 2011)

Microa said:


> The diameter of the board is 22mm. The diode size is SMC. Of course, you can replace it by the SMA size diode such as CMS04. I made this driver for testing and I had the diode on hand in my component boxes. The driver was quite hot when it was driven at 2.5A. I made some metal filled viases conducting the heat to the bottom layer as heat sink or thermal contact. It is a very reliable driving IC indeed.
> 
> The new home of the driver




how much for two of them  ??


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## Microa (Nov 1, 2011)

I have not counted the cost. I bought the IC at US$0.50/pc for 10 pieces excluding shipping charges.


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## VegasF6 (Nov 1, 2011)

Microa, I have been unable to find this IC anywhere for sale in the U.S. If you have access to some more or perhaps a contact I would be appreciative! Looking to get at least 10, maybe 20.

Thanks!


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## Roger555 (Nov 1, 2011)

Microa said:


> I have not counted the cost. I bought the IC at US$0.50/pc for 10 pieces excluding shipping charges.[/QUOTE
> 
> Actually what I meant are you willing to sell me a couple modified.drivers? I really need a good set of 2.5 amp drivers for my xml project.


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## Microa (Nov 1, 2011)

I am sorry that I am not going to sell my modified drivers. I made it for fun.


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## malow (Nov 2, 2011)

just to inform, i just received 10x ax2002 drivers from focalprice (SKU: _LFD29X)_. i was afraid it would be one of the variations around (like some users mentioned from the same driver from dealextreme), but all where ax2002 exactly like this one:

http://i.imgur.com/ZjtF4.jpg

ax2003 would be better for my needs, but $1.34 for each unit was very good.

XML's, here we go


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## Microa (Nov 2, 2011)

VegasF6, The AX2003 is difficult to find in China too. Microbridge is the agent of this IC in China but they are wholeseller not interested to sell small quantity to DIYers. I tried to contact the supplier which I bought from him last time and regret to find that he was out of business. I have 8 pieces left. Do you think these can help?


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## VegasF6 (Nov 2, 2011)

Well I wouldn't want to take the only one's you have on hand, especially not all of them. If it wouldn't be too terrible an inconvenience I might consider buying 2 of yours but honestly, it may not be worth the trouble for you. 

Initially I had hoped to make up some 3A adjustable boards, but if there is no available supplier probably best I just find another IC. 

Thanks for taking the time to try and find them though, that was generous.


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## Microa (Nov 2, 2011)

VegasF6, PM your address. I will send you the Christmas present.


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## Microa (Nov 16, 2011)

Hi VegasF6, Your PM inbox was full. I would like to reply your question here. I have only tried to drive a single XML at 3A with a 18Vdc switching power supply. According to the data sheet, Vin 3.6-23V, Vout 0.25-Vcc, I think it is capable to do the job if you have taken good care of the spark pulses of the engine. The data sheet is available here. http://www.micro-bridge.com/AX2002_AX2003.asp


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## VegasF6 (Nov 16, 2011)

Got that all cleaned out, thanks. Looks like a winner!


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## Roger555 (Nov 26, 2011)

Microa- I have several of these "older" drivers frim DX with the AX 2002 IC. If I wanted to achieve a similar 2.5 A driver could I swap out the IC to the AX2003 (If I can find one) , replace the diode with a 3A (CMS04) & what about the inductor what size or model did you upgrade to?

This is what I have right now


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## Microa (Nov 27, 2011)

The model of the inductor is TCRH104R-220K(22uH) shielded type inductor. 10.3 x 10.4 x 4mm Idc max 2.9A Irms max 2.5A. The inductor on the DX board is TC0504 sizes is 5.8 x 5.2 x 4.5mm which is about 1.5A rated. If the sizes is your contraint, try to find a 10uH with the highest possible current rated inductor. The near biger size TC0705 is 7.8 x 7.0 x 5mm which Idc is 2.3A for 10uH. If you solder it carefully, may be it can fit that tight space.


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## Microa (Nov 27, 2011)

The doide SS34 is already a 3A doide which you need not to change. The sensing resistor I used two R200 in parallel which is 1206 power type rated 1/2W each. normal type 1206 only rated 1/4W. Also, you should take care of the heat generated by the IC. otherwise, the LED will be blinking because the overheat protection will shut off the IC, then it cool down and on again and then overheat shut off ........


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## Roger555 (Nov 27, 2011)

How about this inductor, seems to match the requirements right? Pretty small too 6.47 mm W x 6.86 mm L x 3 mm H 
[FONT=Verdana, Tahoma, Helvetica, Arial]
[/FONT]​http://www.vishay.com/docs/34190/ihlp25cz.pdf
http://www.mouser.com:80/ProductDet...GAEpiMZZMsg%2by3WlYCkUwYD3kRwGDiVuGxgjt7Mxk8=

Also R200 is .20 Ohm right? 

Regarding the IC, I will need to find and replace the existing AX2002 with an AX2003 along with these modifications correct? Too bad I cant seem to find any thus far


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## li_gangyi (Nov 27, 2011)

If there's any sorta of demand for these AX2003 ICs, I could get a friend to source for them.


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## Microa (Nov 27, 2011)

Roger555, The vishay inductor seems OK. R200 is 0.20 ohm +/-1%. The calculation formula is Iled=Vsen/Rsen, Iled=0.25V/0.10R (2 R200 in parallel) =2.5A.
I have 2 pieces left, PM me with your address if these 2 pieces can help. Cheer,


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## moderator007 (Nov 27, 2011)

li_gangyi said:


> If there's any sorta of demand for these AX2003 ICs, I could get a friend to source for them.


Hi li gangyi, VegasF6 was looking to buy 10 to 20 AX2003. You might PM him to see if he is still looking for some.


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## Justin Case (Nov 27, 2011)

The 10uH Vishay inductor might be a better choice than the 22uH. You'll get probably 40% less total inductor loss (maybe 0.6W vs 1W of core, DC, and AC loss), but with more ripple current. The biggest loss component is the DC loss.


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## Roger555 (Nov 27, 2011)

Hey Justin your PM box is full!


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## li_gangyi (Nov 29, 2011)

A little OT, does anyone know offhand if someone makes a multimode driver that uses the AX2002? Or is that gonna be a custom DIY deal?


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## Nil Einne (Feb 2, 2012)

li_gangyi said:


> A little OT, does anyone know offhand if someone makes a multimode driver that uses the AX2002? Or is that gonna be a custom DIY deal?



It's a while later but download used to or may be still does sell AX2002 multimode boards here http://www.candlepowerforums.com/vb/showthread.php?168062-Multi-Sink . I'm not aware of any of the large vendors selling multimode AX2002 driver boards. You can check out Torchboy's http://www.candlepowerforums.com/vb/member.php?23774-TorchBoy driver list here http://www.videofoundry.co.nz/ianman/laboratory/research/driverlist.php . 

Also did you ever have any AX2003 for sale? I can't speak for others but depending on price an AX2003 driver or just the IC will potentially be interesting to me. I've read the datasheet but never seen it tested but presume it's similar to the AX2002 which from testing is a decent driver under 2A. And I haven't yet seen a resonably price driver board that can handle 2.5-3A (for an XM-L for example) with that range of the AX2002 i.e. the 1 li-ion and more category which always surprises me. Even for 2xCR123 the AX2003 should be way better then the AMC7135 that some use when they want 1x18650 compatibility. (Above 6V there seems to be some good price and okay drivers. Well there are some that claim to handle a similar range to the AX2002/2003 and 2.5-3A output but I've never seen them tested.)


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