# High Power LED Driver, 9 amps



## fppf (Dec 8, 2009)

Someone asked me to design a simple high power driver for the SST-90 LED.

UPDATED 12-18-09
All parts are in house for 2 prototype builds, boards are on order, should be here by 12-22-09.
I will be on vacation starting the night of 12-22 through the holidays, so the first build wont be until maybe the last week of Dec.
The following are specs and options for this driver.
Size
The board is 1.2" in diameter by about 0.5" thick. I will fit in a "D" size Mag light.

The voltage input range is 6 volts to 24 volts. The board will not operate any lower than 6 volts because of gate drive issues with the mosfet.
The input is NOT reverse protected, care must be taken during hook up. This is mainly due to size and efficiency issues.
The input to the board is ESD and transient protected. The protection starts to conduct at about 28.9 volts, if you apply this it will damage that part.
The board it self is ESD sensitive, proper ESD handling procedures must be followed. Most LEDs are ESD sensitive also.

Low voltage drop out setting.
The board can be configured at time of order to turn off at a certain voltage. This is to protect the board and the batteries.
The default voltage that will be shipped is 10 volts.
No charge options for the voltage drop out are 6v, 10v, 11v, 12v, 13.1v, and 14v.
You must apply about 0.5 volts more than the drop out voltage for the driver to turn on.
Once on it will turn off when the input drops to the set voltage.
Other voltages can be custom set but may incur an additional charge for me to order more parts.

Output
This is a true constant current driver.
The user has some options when ordering for the current set points.
There are 2 connections on the board, shorting either to ground will select one of the current settings.
The user can order the following current settings 5, 6, 7, 8, 9, 10 amps on either selection.
So you can have 2 different drive currents.

The user could also hookup a user supplied 100K pot for linear dimming. You must specify you want to do this
at time of order and you can not use the switch method as above.

When ordering you must specify the forward voltage of the LED you plan to drive.
The design forward voltage is between 2 and 4 volts. If you want to work outside that range I can adjust the driver to do so on a special bases.
Driving voltages outside of the designed range could damage the board.

The board has output open protection if the LED where to open or become disconnected.

Should be able to start shipping sometime in January.
The cost will be $50


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## Doh!Nut (Dec 9, 2009)

As lights are generally cylindrical, most people like/expect a round driver, but more importantly the biggest single market I suspect will be Mag conversions.
Can you confirm that it would fit inside a D-Cell Maglight tube? 
It would be preferable, from a packaging point of view, to fit against the back of the heatsink rather than being lengthways.
The HipFlex is 1.4" round and just a bit too big.

ps I like the format that allows a low current trigger to be used rather than pushing full power through the switch.

Nick


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## SUBjohan (Dec 9, 2009)

Is this a true Constant Current driver?
If so I need at least one, and if you can make them fit in a D-cel mag I am going to need more!!

I think there will be a huge market for a true CC driver wich can deliver 10A and can handle at least 20V input.

Greetz Johan

P.s. Have you got some efficiency numbers for a 14,8V supply and 1 SST-90 @ 9A?


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## rayman (Dec 9, 2009)

I would be in if it would fit in a D Maglite and if the price would be lower .

rayman


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## SUBjohan (Dec 9, 2009)

rayman said:


> I would be in if it would fit in a D Maglite and if the price would be lower .
> 
> rayman



I think that US$50,- is a fair price, it is only €33,- just a bit more than Der Wichtels driver. But it is capable of 10A


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## tx101 (Dec 9, 2009)

I'm in for at least one board

D Mag size would be great

What kind of time frame are we looking at before we can actually get
our hands on them ?


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## clint357 (Dec 9, 2009)

These would be awesome for automotive applications. how many SST-90's could one of these drive?


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## rokspydr (Dec 9, 2009)

I'd be in for one too


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## Illum (Dec 9, 2009)

Doh!Nut said:


> As lights are generally cylindrical, most people like/expect a round driver, but more importantly the biggest single market I suspect will be Mag conversions.
> Can you confirm that it would fit inside a D-Cell Maglight tube?
> It would be preferable, from a packaging point of view, to fit against the back of the heatsink rather than being lengthways.
> The HipFlex is 1.4" round and just a bit too big.
> ...



When it comes to prototyping drivers...
Build and perfect your circuit on a breakout board first, when you have all the components right _then _figure out a way to stuff them into a round volume.

theres enough space in a mag D body to stack 2 trimmed boards, that should be plenty of room for those "bigger" components


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## fppf (Dec 9, 2009)

Ok to answer the questions:

This is a true current source. It is a buck topology converter. There will be some ripple current but not much and it will be at a very high frequency. To make a converter handle this much current requires some larger components. All these components tend to be square in shape. So a round board is a little harder. I did some quick layout options and the smallest diameter I can go it 1.2" maybe a little bigger. I will work on that and let everyone know. Board coverage is already VERY high.

Efficiency should be somewhere between 80-90%. Its hard to calculate and until I build some and measure it that is as close as I can get. But I sacrificed a little efficiency for size.

I don't think I can get the price any lower. Because of the high current the cost of components goes up. Also building low quantities drives the prices higher and I don't plan on the demand being high enough to justify true production runs.

I think with some component changes we could drive at least 3 SST-90s in series.

Time frame has now been pushed out by needing a new board layout 

I will work on the new layout and let you know. The design is finished. Boards I get from a prototype house and take about 3 days to turn. All components are in stock at various suppliers and should take about a week to get here. Then I need to build and verify the design. Everything said and done we are most likely looking some time in Jan 2010.

I don't have any of these LEDs for testing. I'm just going to drive the power into a few power diodes I have that can generate the same Vf at that current for testing. There cheaper if I blow them up.


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## fppf (Dec 9, 2009)

Illum said:


> When it comes to prototyping drivers...
> Build and perfect your circuit on a breakout board first, when you have all the components right _then _figure out a way to stuff them into a round volume.
> 
> theres enough space in a mag D body to stack 2 trimmed boards, that should be plenty of room for those "bigger" components



Because this is a higher power high frequency drive, bread boarding is out of the question. Bread boards and wire wrap just create issues in the design. Even brass boards will have parasitic and power issues. The easiest way to prototype these designs is to just get a run of boards made so you can measure what the final product will preform. That and all the parts only come in SMT.

2 boards would not help either. When designing high current and frequency switching drives you need all the components as close together as possible. Spiting up the components on separate boards is going to cause tons of EMF, parasitic, and transient issues. The size of the board is being driven by 4 main components. I will try to make the smaller board but heat maybe an issue then as well. The board is used to dissipate heat. The smaller the board the less area you have to shed the heat.


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## overdog (Dec 9, 2009)

This is good news!
I would be in for one to drive 3 SST-90 in series...


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## Hallmcc (Dec 9, 2009)

I'm in for 4


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## fppf (Dec 9, 2009)

Ok, I was able to get the board to 1.2" in diameter. That is slightly smaller then a "D" size battery (1.35"). However for the smaller size I had to give up some things.

I will need to check the heat dissipation of the board when I build it. I had to reduce the size of the power plain which will reduce cooling surface area.

There are only 3 main connections, + power, -power, and + LED. The ground to the LED will need to be connected in your wiring. There was no room on the board left for another hole. There is a 4th smaller connection for a switch. When this connection is pulled to ground the drive will turn off. However there will still be some current draw. The chip specs say 100 uA and the 10K ohm load through the switch. Also there are leakage currents through diodes, caps, and other parts.

Finally, there are no mounting holes. The board will need to be attached to something with epoxy, RTV, double sided tap on the bottom, ect. You should be able to encapsolate the whole board if you want provided you use a thermal conductive epoxy.

The price stands at $50 plus shipping. I think there is enough potential demand to warrant going forward. I should place orders for boards and components by the end of this week. Then build up and test 2 units. If the tests come out good I will take some orders and ship.

When you order you must specifiy the input voltage range you plan to use, the current drive you want, and the planned Vf of the LED. You also need to specifiy the Minimum operating voltage you would like. This will turn the drive off when the batteries get low to protect the cells. I need this information so I can tweek the control points and make the drive most effcient.

Please feel free to post any comments. More information to follow.


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## cmacclel (Dec 9, 2009)

I have an SST-90 here. If you want me to test one of your boards for you send me a PM.

Mac


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## Packhorse (Dec 9, 2009)

See I told you there would demand for this driver!

I get the 1st two boards right?

Is there any way to make this a multi mode board?
Perhaps by using a already available off board board?

Does it have protected output? EG if there is no load will it fry?

Can you leave the enable pin connected and just switch the Vin to it?


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## fppf (Dec 9, 2009)

Packhorse said:


> See I told you there would demand for this driver!
> 
> I get the 1st two boards right?
> 
> ...



Yes sir, you get dibs after verification. :buddies:

You can PWM the disable line for true color dimming if you would like. I was going to test it to see how it works. If I used a pic chip I could do what ever you guys want. Which I may do in the furture, but for now I'm using a standard controller. I don't see a problem with just leaving the disable line not connected and switching the Vin. That is something I will test to make sure. The transient protection should snub out any unwanted startup ringing. An open output should be just fine. The driver has fly back protection and all items are rated for the input voltage.

I'm really tied up working on a high wattage DC HID ballast that has been a pet project for 2 years now. So it would be a long time before I get a pic chip version.


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## supasizefries (Dec 10, 2009)

Subscribed.


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## Aircraft800 (Dec 10, 2009)

It really needs to fit a Mag D Tube 

It would probably be O.K. if you had to split it into 2 boards, as long as the components that need heatsinked are all on the same board so it could be mounted to the LED heatsink.

Watching this one for updates!!


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## fppf (Dec 10, 2009)

Read my previous posts.
I was able to get the board down to 1.2" in diameter.
A "D" cell battery is 1.35" in diameter. It should fit now.


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## monkeyboy (Dec 10, 2009)

This is the driver everyone has been waiting for. Good luck with your project. I think a lot of people will pay $50 for this driver so long as it runs reliably without overheating issues. Top bin SST-90s are still hard to get hold of but that should change soon.

I would be interested in one that could run on 4 x NiMh D size and had no low voltage cut out so it would just run in direct drive as the batteries depleted. Is this possible?


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## fppf (Dec 10, 2009)

monkeyboy said:


> This is the driver everyone has been waiting for. Good luck with your project. I think a lot of people will pay $50 for this driver so long as it runs reliably without overheating issues. Top bin SST-90s are still hard to get hold of but that should change soon.
> 
> I would be interested in one that could run on 4 x NiMh D size and had no low voltage cut out so it would just run in direct drive as the batteries depleted. Is this possible?



There needs to be some cut off point of at least 6 volts. This is to protect the circuits and is the lowest operating voltage allowable. Any lower and the fets wont fully conduct and it will over heat.


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## jasonck08 (Dec 10, 2009)

Definitly not interested @ $50. If it were half that price or less, then I'd be interested. I'm cheap. Most of my mag builds are done for <$50 LED and driver included.


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## fppf (Dec 10, 2009)

jasonck08 said:


> Definitely not interested @ $50. If it were half that price or less, then I'd be interested. I'm cheap. Most of my mag builds are done for <$50 LED and driver included.



Then I don't think you will be using this LED, which costs almost $50 alone. So then you don't need to worry about the high power driver.

But, just so you know, I'm not really making even enough to really be worth my while. I just do this as a hobby and enjoy the challenge and fun in addition to my normal job. The costs involved for this driver are very high. You need high current capacity magnetics. I can't use a normal size inductor because of the size constraints. So I need to use more capacitors to keep the ripple current low. Because the ripple current is high on the inductor it will be high on the capacitors. So that means I need to use multiple special low ESR caps. I need a FET that has low gate threshold, very low Rds, and very low gate charge, which if you try to find, is tough. So because all of these special drive components the cost is high, and I did not even include the controller or getting boards spun.

So unless I start getting people that want to order 1000 of these things at a time, which I don't see happening, and I don't even think I would support, the price is what it is. I already have over 100 hours of design work tied up between initial concept, part mining, part calculations, board layouts.

Just for an update for everyone that is interested I'm going through final board checkout and parts lists. I should be placing the parts order sometime tomorrow. I will order parts to be able to set the current from 5 up to 10 amps in 1 amp steps. The under voltage threshold will be able to be set from 10 to 14 volts in 1 volt steps with a 0.5 volt hysteresis. I will also provide a 6 volt threshold for those that don't want it. I can set other values but I will do those on request. It will require me to order more parts and I will discuss it as the need comes up. When I get the parts in (a week or so) I will do final footprint checks and get boards ordered.

I know some guys want to use 4 NiMH cell lights. I will try to test the driver down to 4 volts (the gate threshold is 3V max) but the controller spec notes a minimum working voltage of 6 volts. Maybe in the future I can use a different controller and get operation down to 4 volts if this does not work. But for now I would like to stick to this and see how it goes.


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## bigchelis (Dec 10, 2009)

Awesome idea...

Im in for one:thumbsup:

The SST 90 at 9A = :twothumbs:twothumbs:twothumbs:twothumbs

No more stinking direct drive. Now, with that much current I need to stock up on IMR 26650 cells!


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## Linger (Dec 10, 2009)

Can we start an interest list then if you're ordering parts?


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## fppf (Dec 10, 2009)

Linger said:


> Can we start an interest list then if you're ordering parts?



Not as of yet....
My first parts order will be for 2 units, which I will build up and bench test. Most likely end up destructive testing one of them. I don't want to sell something that is a piece of junk.

After testing I will post the results for efficiencies and all that good stuff so people will know exactly what there getting. Then I will start a list and give info for buying and shipping.


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## SUBjohan (Dec 11, 2009)

fppf said:


> Not as of yet....
> My first parts order will be for 2 units, which I will build up and bench test. Most likely end up destructive testing one of them. I don't want to sell something that is a piece of junk.
> 
> After testing I will post the results for efficiencies and all that good stuff so people will know exactly what there getting. Then I will start a list and give info for buying and shipping.



Verry good, I like the way you work!!:thumbsup:
I am in for 3


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## fppf (Dec 11, 2009)

SUBjohan said:


> Verry good, I like the way you work!!:thumbsup:
> I am in for 3



I'm a fellow diver and an aerospace guy 

Boards checked out, parts list is done, ready for parts order in the morning.
I have a stock D cell mag light here, I pulled the front cap off. The board will fit inside the body tube and easily inside the head.


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## BVH (Dec 11, 2009)

fppf said:


> I'm really tied up working on a high wattage DC HID ballast that has been a pet project for 2 years now.



This perked my ears up! I'm an HID kind of guy. Can you divulge anything at this point?


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## monkeyboy (Dec 11, 2009)

fppf said:


> There needs to be some cut off point of at least 6 volts. This is to protect the circuits and is the lowest operating voltage allowable. Any lower and the fets wont fully conduct and it will over heat.



Fair enough, I've noticed that about other high current buck drivers too. What would be the acceptable battery configurations? Would 5 x nimh work or would that go below the acceptable voltage under load?

I guess 6 x NiMh or 2 x li-ion would be OK with 6v cut-off

What about 2 x LiFePO4 (like this one) with it's lower nominal voltage of 3.2V?

3 x LiFePO4 should work well with a cut-off of 6v since recommended minimum cut-off for these cells is 2.0V

Would you be selling these with a choice of cut off voltages or all the same?


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## fppf (Dec 11, 2009)

BVH said:


> This perked my ears up! I'm an HID kind of guy. Can you divulge anything at this point?


All I'm saying now is that I'm trying to make a compact 150 watt HID light for diving. I'm working on the ballast design and I'm almost ready to order boards. The magnetics on this project where the hardest part. Because of the low input voltage the current on the input stage is very high, which runs me into the same issues as this little project did. I don't know if it will be any use above water because the thing needs to dissipate a LOT of heat. You may not be able to hold it in air after its on a few minutes.




monkeyboy said:


> Fair enough, I've noticed that about other high current buck drivers too. What would be the acceptable battery configurations? Would 5 x nimh work or would that go below the acceptable voltage under load?
> 
> I guess 6 x NiMh or 2 x li-ion would be OK with 6v cut-off
> 
> ...



Yes, I will set the current and under voltage shut off to what the person wants. I ordered a range of parts to set current at 5, 6, 7, 8, 9, 10 amps. And UV ranges of (turn on, then turn off) 6.1,6; 10.5,10; 11.5,11; 12.5,12; 13.6,13.1; 14.5,14 the reason for the hysteresis is to prevent cycling.

I can set other ranges of values but it will take some time to order more parts in.

If you order the 6 volt value I would not suggest using an input voltage any higher then 10-12 volts because the values of the resistors are lower and will start to draw some current (5 mA at 24V)

I would suggest a battery setup so that the minimum operating voltage of the cells is at the 6 volt level. So 6 NiMH would have a shut off of 6V and a full charge of about 7.2-7.8 volts.


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## Dark Laser (Dec 11, 2009)

Might it be possible that we will see a driver that can push 9A to the LED with just 4 (D-Cell or High-current such as Sub-C) NiMHs?

Otherwise, the idea of using 6 NiMHs is great, too. 50 $ is really not too much - I think it is a very fair price! It's not just the materials - it is also the work that needs to be paid...


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## BVH (Dec 11, 2009)

fppf said:


> All I'm saying now is that I'm trying to make a compact 150 watt HID light for diving. I'm working on the ballast design and I'm almost ready to order boards. The magnetics on this project where the hardest part. Because of the low input voltage the current on the input stage is very high, which runs me into the same issues as this little project did. I don't know if it will be any use above water because the thing needs to dissipate a LOT of heat. You may not be able to hold it in air after its on a few minutes.



Yes, I know what you mean. I have a few 12V (9V to 32V), 120 -125 input Watt ballasts that hit, IIRC, 155 degrees F after about 15 minutes running in a vented enclosure. It began to melt some of the potting material. It's a 4 3/8"L x 3 1/2"W x 2"H casing but needs another 1 1/2" in length to accommodate the input and output wires, seals etc. It is multi-stage output. One of them provided 105 Watts to the bulb.


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## fppf (Dec 11, 2009)

Honestly I don't know if it will be possible for a high current driver that will be small and run at 4 volts. It was tough finding a fet that would work with a 6V application at these current and frequencies. If I have time I could look into it, but it wont be soon.


I have the design and simulations done for a 24VDC 400 watt HID ballast 
Don't know if it will ever make it out of simulations, but it was fun to try.


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## BVH (Dec 11, 2009)

fppf said:


> I have the design and simulations done for a 24VDC 400 watt HID ballast
> Don't know if it will ever make it out of simulations, but it was fun to try.



If it does, please keep us HID nuts informed over in the HID section. We absolutely love anything HID. What would be some of the candidate bulbs for the 400 Watt'r? With a 6 or 7 cell, 12-14 AH Lipo, we might get 20 to 25 minutes of run time which is plenty for demonstration lights. I'd love to see something like this give my 350 Watt Locators a run for their money!


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## fppf (Dec 11, 2009)

BVH said:


> If it does, please keep us HID nuts informed over in the HID section. We absolutely love anything HID. What would be some of the candidate bulbs for the 400 Watt'r? With a 6 or 7 cell, 12-14 AH Lipo, we might get 20 to 25 minutes of run time which is plenty for demonstration lights. I'd love to see something like this give my 350 Watt Locators a run for their money!



Any type of bulb can be used with my ballast design. I have already done some prototypes on the bench. I can drive 400 volts to the bulb for self starters and I can pulse 5 kV to the bulb for pulse arcs. After the bulb starts its all just control, which is custom software based, so it can drive anything.


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## jasonck08 (Dec 11, 2009)

fppf said:


> Then I don't think you will be using this LED, which costs almost $50 alone. So then you don't need to worry about the high power driver.


 
I'll definitly be using the SST-90 in future builds. Sure its expensive @ $45 for the highest flux bin, but you can drive it pretty well DD off 4xNi-mh's. People in the DIY section have had some great results driving the LED @ 9-10A.


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## fppf (Dec 11, 2009)

jasonck08 said:


> I'll definitly be using the SST-90 in future builds. Sure its expensive @ $45 for the highest flux bin, but you can drive it pretty well DD off 4xNi-mh's. People in the DIY section have had some great results driving the LED @ 9-10A.



They are relying on the internal resistance of the cells. And there are a few threads over there of "I blew up my $50 LED :mecry:" . If you hooked up 4 NiMH cells of 4.8 volts, and it really gave the current the LED would draw, it would blow up for sure. Then if you look at the maximum discharge rates for the cells some maybe exceeding them, which will shorten the life of the cells.

Now, if you direct drive with 3.5 volts or less, then you should be safe.

So doing direct drive is a crap shoot, it depends on the tolerance of the cells used, the LED and some other factors. But hey, your more then welcome to do what you want.

Me personally, I like to do things the proper controlled way. If the LED calls for a max of 9 amps I want to control it at 9 amps. Not plug and pray.


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## fppf (Dec 11, 2009)

Just an update folks, all parts are ordered and shipped today. I expect them end of next week. Then I will verify all foot prints on the board and get the boards on order. The board shop I use will turn them and have them here in 3 days from time of order.


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## Aircraft800 (Dec 12, 2009)

Luminus Devices SST-90-W65S-F11-GN102 (top bin)
From avnetexpress: $45.00
Tax: $4.37
Freight per shipment: $8.00
*Total US$: $57.37*
The look on my face when I blow it , Priceless!!

*I'll need that driver!*

Thanks for the update!!


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## overdog (Dec 12, 2009)

Hello fppf,
as I said, I am in for one driver to drive three SST-90 in series, powered by four IMR 18650 in series. Will your driver be able to manage this?

Thank you & best regards,
Steffen


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## fppf (Dec 12, 2009)

overdog said:


> Hello fppf,
> as I said, I am in for one driver to drive three SST-90 in series, powered by four IMR 18650 in series. Will your driver be able to manage this?
> 
> Thank you & best regards,
> Steffen



Yes it should be able to drive the LEDs. I will need to adjust some components on it.
However, the battery maybe an issue. The minimum voltage for that cell is 2.5 volts, 4 would be 10 volts.
The Vf at 9 amps would be about 3.6 volts. So the batteries would not be able to drive the full 9 amps to discharge.
Also the Max Discharge current for that cell is 4.5 amps, way under the 9 amps that would be drawn near discharge.


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## overdog (Dec 12, 2009)

This sounds good,
I have one more question, is it also possible to put a dimming option on this board, just 2 modes like "low" and "high"- to have the option to run on low and save power and to have the high mode for real fun?


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## fppf (Dec 12, 2009)

overdog said:


> This sounds good,
> I have one more question, is it also possible to put a dimming option on this board, just 2 modes like "low" and "high"- to have the option to run on low and save power and to have the high mode for real fun?



I edited my last post about the battery, I jumped to soon without looking up those cells.

Because of the size constraints I did not do any on board dimming. You can dim the board using PWM on the disable line. I'm looking into putting some more through holes on the board to maybe allow a potentiometer to be hooked up for analog dimming. But again, the board is so dam small and populated it will be tough.


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## ergotelis (Dec 12, 2009)

subscribed! Can you please look into any plans to make a driver with multiple mods or any trim pot on the circuit? 
Pleaseee....!!!
At least modes would be amazing to be put!Thanks!



edit:
It is ok man, don't answer ,i got it! While pming overdog, he was asking the same thing i wanted!


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## overdog (Dec 12, 2009)

O.K., so I could connect it to a D2Flex from DIM on your board to PWM at D2Flex? And I think you got something wrong from the specs of the IMR cells,
Nominal Voltage : 3.7V 
Capacity : 1600mAH 
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 4.5A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 10C/ 16A
Operating Discharge Temperature : -10 - 60 Degree Celsius

... or do I misunderstand this, ... I know, many questions, but with your driver you will save lots of emitter- lives....
thanks & best regards,
Steffen


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## fppf (Dec 12, 2009)

Battery space lists different specs for that cell.
The lowest discharge voltage is lower then the combined Vf of the LED.
But that spec lists a much higher discharge rate.

I would need to look at that controller. You need an open drain switch to pull the Disable line down. I will also test what frequencies will work best for the PWM.


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## overdog (Dec 12, 2009)

Here is original sales thread of those AW IMR 18650, I think, most people here use them: http://www.cpfmarketplace.com/mp/showthread.php?t=191277 - and it would be nice to make your converter work with D2Flex from Taskled, http://www.taskled.com/d2flex.html this board is able to handle something about 10Ah (recommended for 6Ah), and if you use this, you already need a momentary switch.


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## fppf (Dec 12, 2009)

So, I would not recommend putting a switch between the output of my driver and the LED. This will cause my driver to over charge the output capacitors due to the open LED. Then when the LED is reconnected it will over current the LED until the caps bleed back down to the proper levels. So PWMing the ouput my driver will lead to a higher than wanted current operation of the LED.

I provide a pin on my board I labeled "Dis" for Disable. This pin is pulled to Vin through a 10K resistor. If its not connected to anything the driver will just operate normally. If you pull the pin to ground it will disable the driver. You can PWM this pin. If you hooked this pin to the -LED of the D2 Flex it would drive my circuit. However, the dimming would be inverse of what is expected. This is because when the D2 Flex turns an LED On it would be really pulling my disable pin low, which turns my driver off.


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## cmacclel (Dec 12, 2009)

It's great that your designing a driver that outputs 10 amps but in *my* opinion it's not practical unless it has at minimum 2 levels. Everyone here wants this driver to power the SST-90 LED's and most of them plan on using a Mag host. You Can't run an SST-90 at 9 amps for very long in a mag host as there in no where near enough mass for heat dissipation. 

Mac


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## overdog (Dec 12, 2009)

...think the same, as long as you design and are able to change things, may there is a way to keep the board small enough to fit in a Mag but to put 2 levels on it- this would be really helpful and make this driver ready to use for future...
...but thank you for realizing this driver- anyway, without this the SST-90´s are far away from being useful for designing practical flaslights...


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## fppf (Dec 12, 2009)

cmacclel said:


> It's great that your designing a driver that outputs 10 amps but in *my* opinion it's not practical unless it has at minimum 2 levels. Everyone here wants this driver to power the SST-90 LED's and most of them plan on using a Mag host. You Can't run an SST-90 at 9 amps for very long in a mag host as there in no where near enough mass for heat dissipation.
> 
> Mac



Well if you guys want to solder onto pads rather than through holes and want to use a make before break toggle switch I can give you 2 current levels. If you use a standard break before make switch you will get a small current spike during the transition. Or if you want to use a pot I can give you pads for that as well. There just is no room left on the board for anymore holes. Just FYI to have a PC board trace carry 9 amps without becoming a fuse it needs to be at least 0.1" wide depending on the length. So almost all of this board is trace and power drive. There are reasons guys are not whipping out these drivers left and right, like all the low power drivers.

But everyone wants this and that, then cry that its to big or to expensive or it wont get done fast enough.

I'm doing the best I can to get you guys what you want, but there really is not a big enough market to justify in my mind the effort to use a custom micro and start stacking multiple boards. Don't get me wrong, I can do, it can be done. Its just a cost vs time vs return issue.


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## overdog (Dec 12, 2009)

...you are completely right, its just collecting some ideas to improve-
if I need modes, this time i´ll have to put in a second board, which also needs space and costs money+ : so why not designing a little bit bigger but still fitting board and spending more money on your board than having to pay for two boards- that was the idea- I never expected that you could manage this at the same price or size for your board.


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## A380 (Dec 12, 2009)

I think that the idea of a pot is great.
Also would be great to have something similiar for the sst-50 (5amps).


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## fppf (Dec 12, 2009)

Well I can give you the pot option and the switch option, you will just need to solder some small gauge wire to some surface mount pads at the edge of the board. Then apply some RTV or potting compound to strain relief.

The board is already at the maximum size most will buy. If I make a rectangular board that fits length wise into the can I can add room for more through holes.

The circuit design is easy to use, its just a size issue for external connections. The board can be order to drive at 5 amps as well.


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## fppf (Dec 12, 2009)

Anyone have any issues using 16 awg wire or smaller for supply and LED and 24 awg wire or smaller for the disable, power select, or power potentiometer lines? I think I MIGHT be able to fit those size through holes if I change some other components to free up some board real estate.

Speak now or hold your peace 

Just to Recap
16 awg wires for supply and LED, there can be 4 connections + in, -in, +LED, -LED

24 awg wires for control lines, disable, switch common, switch hi, switch lo, ground. The pot would use the same connections as the switch. You can not use a switch AND a pot at the same time, its either/or.

Board size would not change and I will eat the little cost increase from the component change.

For $50 I should get a case of beer with each payment as well :thinking:


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## A380 (Dec 12, 2009)

Maybe its a stupid question, but is 16 awg wire necesary to carry 9 amps?
I know you said not to use both on the driver,but could it be posible to use the pot and have a switch betwen bat and driver?


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## fppf (Dec 12, 2009)

A380 said:


> Maybe its a stupid question, but is 16 awg wire necesary to carry 9 amps?
> I know you said not to use both on the driver,but could it be posible to use the pot and have a switch betwen bat and driver?



Not a stupid question, the current capacity of a wire depends on many things. The main item is heat and power losses. Wire in free air can carry more current and stay within the limits of the insulation than a wire in a conduit or container.

The smallest wire I would use for 9 amps is 18 awg, but 16 gives more margin, less heating, and power loss. I'm also using the wire to conduct some heat off the board. I wanted to use larger holes for more solder mass.

You can use the pot option and the disable line to turn the circuit on and off. You can also switch the input power like your asking, but then the full current will be going through your switch. You just can't PWM the power input or the LED output.


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## fppf (Dec 12, 2009)

Ok
I was able to change some componets around and get just enough spacing to put 4 through holes on the other side of the board. I reduced the main connections for power and LED so there are now 4, I just added a ground through hole for the LED to make wiring easier.

The 3 new connections will allow for 2 power settings OR a pot hookup for analog dimming. The disable line is still there for PWM dimming and to turn off the driver with a low current switch.

The 2 power setting option needs and external SPDT switch. There is a "Hi" pin and "Lo" pin and a "G" ground pin. Pulling the hi or the low to ground will give the different power levels. I could calculate what the current would be if you pulled both to ground at the same time and that would give you 3 levels but they would be dependent on each other and limited in selection of current levels.

A word of warning about this!! IF you fail to pull either pin to ground the driver will go to full current, which is about 12 amps. So if you hook up the board without your switch or the wires to your switch break, full power Mr Scotty. Now, to address the short amount of time the switch is switching and bouncing between the two terminals I added a small RC filter in there. So as long as your switch does not hang and switches within a few mS the current wont go nuts.

I will ship the boards with a jumper installed to the Hi setting for those that don't read directions first and just hook stuff up. You can pull out the jumper and connect your wires.

For the pot option I need to put other values on the board so you must specifiy the pot option when you order. The pot will be connected between the "G" and "Hi" connection. You need a 100K ohm pot. This will give you 9 amps at 100K and 4 amps at dead short. The current going through the pot is very tiny so no issues there. Again, same issue with the open wires, full current.

Is everyone happy now? :ironic:


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## SUBjohan (Dec 13, 2009)

fppf said:


> Is everyone happy now? :ironic:



Yes SIR!!!
And now go do some tests so we can order some 

Technical question, how do you measure the current? By Shunt resistor or via a different way?

Greetz Johan


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## fppf (Dec 13, 2009)

Parts should be here next week.

Current is measured by shut resistor. But its a resistor designed for current measurement and is configured as a kelvin measurement.


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## rokspydr (Dec 13, 2009)

WOW this great, thank you.


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## Aircraft800 (Dec 13, 2009)

Yea, just go ahead and put me on the buy list. You're obviously a electronics guru, and your component talk is way above my head.



Thanks for the updates!


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## fa__ (Dec 13, 2009)

All this looks very nice and is interesting to read, thanks :thumbsup:


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## nailbender (Dec 13, 2009)

Hi 

I just saw these cool. 

I would be in for a 3 or 4 of these and I think the price to be fair for what you are doing and the parts needed. 

thanks for considering these.

Dave


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## AaronM (Dec 13, 2009)

fppf,
Can you make this driver work with a Luminous CSM-360? It requires four times the voltage of the SST-90 and I know I can only expect one fourth the current...still, the efficiency would amazing.


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## fppf (Dec 13, 2009)

AaronM said:


> fppf,
> Can you make this driver work with a Luminous CSM-360? It requires four times the voltage of the SST-90 and I know I can only expect one fourth the current...still, the efficiency would amazing.



Yeah, we can drive that one too. It would require some changes to values but should not be an issue.


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## Pin (Dec 14, 2009)

Yep, count me in...
...this is what we've all been waiting for (and not smart enough to do ourselves). I think the price is fair....and I think we take your effort for granted...so, "Thanks!". 

Now, to pull my finger out and get started on a host...


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## paetzi (Dec 14, 2009)

I´m also in for one.
But i still have a question. 
If i take the pot option. Is it still possible to disable the driver with a switch?


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## AaronM (Dec 14, 2009)

Yay!
I'm in for one with a 12~13V output.


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## fppf (Dec 14, 2009)

WOW, and who said the USPS is dead?
I have the parts in hand already! :twothumbs

I will review the board layouts one more time and confirm package sizes and spacing. I should be able to order boards tonight and maybe just maybe have some built by the weekend.


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## rokspydr (Dec 14, 2009)

wow pretty fast


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## AaronM (Dec 14, 2009)

Is it a buck only driver? I suppose it wouldn't need to be anything else for a single SST-90. Any idea what battery voltage I would need to maintain for my propposed 13V load?


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## fppf (Dec 14, 2009)

AaronM said:


> Is it a buck only driver? I suppose it wouldn't need to be anything else for a single SST-90. Any idea what battery voltage I would need to maintain for my propposed 13V load?



Yes, its only buck, no way buck/boost would fit on this tiny board.
The design will let you operate all the way into and past dropout. However the way the controller measures and controls current when you get to drop out you will see LED current increase by half of the inductor ripple current, which is about a 0.5 amps increase. So I would suggest keeping Vin a little above the voltage of Vf at If +0.5 amps. There is a lot of inductor ripple current because you need a large inductor to carry the current but we have no space for a large value inductor. So I had to use a smaller inductor with a lot of caps.


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## paetzi (Dec 15, 2009)

If the driver is build for the use with a 100k pot can it still be turned off via a switch?


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## lucca brassi (Dec 15, 2009)

@fppf

*May I ask you which IC you will choose for current driver.*


At the moment I make some experiments with LT3743 (buck), but I made tests only with resistor instead of LED ( waiting on SST :tired ,need some fine tuning..... then aluminium PCB ( on next company order) 

Regards


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## fppf (Dec 15, 2009)

paetzi said:


> If the driver is build for the use with a 100k pot can it still be turned off via a switch?


Yes, Disable line always functions.




lucca brassi said:


> @fppf
> 
> *May I ask you which IC you will choose for current driver.*
> 
> ...



I'm not willing to share that, sorry, maybe after I start making them.


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## fppf (Dec 15, 2009)

So I did some more thermal analisys on the board.

I think there is going to be a heat issue with the mostfet still. All the other componets should operate about 20 degrees C above amdient, but the fet is looking close to 70-80 degress. Which means, inside the light it may cause it to over heat because of the rise in ambient temperature.

How do you guys feel about me using a TO-220 package that needs to be heat sinked? It would fit on the board and we can lay it down so it would not add that much hieght. We are just pumping a ton of current. The other option I'm looking into is using a larger SMT package, but because the board is so small there is not a lot of heat transfer happening there. But a larger fet would have lower Rds which will help a lot.


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## fppf (Dec 15, 2009)

Ok, I think I found an SMT fet that will handle the power without cooking.
I also changed the board layout to better dissipate the heat.

I should have boards on order tonight. But it maybe next week until I get a chance to build them up. More to follow.


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## stub (Dec 15, 2009)




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## fppf (Dec 16, 2009)

Boards have been ordered.
Bad news, they need to run on a different line, wont be here until Tuesday or Wednesday of next week.

As long as all the calculations and modeling turn out reasonably correct we should be on target for a January release.


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## paetzi (Dec 16, 2009)

Hi the 100k Pot that i bought has max 84k Ohm.
Is it a problem? How many A will i get out the driver? 
Should i solder a 16k Ohm resistor to it?


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## fppf (Dec 16, 2009)

paetzi said:


> Hi the 100k Pot that i bought has max 84k Ohm.
> Is it a problem? How many A will i get out the driver?
> Should i solder a 16k Ohm resistor to it?



You will want to add a resistor or I can adjust the trim resistor on the board for 84K. Having a lower value pot will just cause a lower drive current. You don't want to high of value, then it could over drive.


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## Linger (Dec 18, 2009)

fppf,
can you put an edit line in the first post that reads something like


* 9amp driver fits [email protected] D*​**(last revision as of Dec. 18) - design updates** 
Input range x - xx volts
_-(you must provide battery information on ordering so components may be adjusted to set maximum and minimum voltage cut-off_)

Output options: with x holes for x or x 
-may attach pwm controller for ...
-can use x for x modes
-may attach a 100k potentiometer for ...... 

Target shipping:late January 2010
Target cost: $65 + shipping, beer optional


////
Some of the discussion is a bit above your readers, even those following the thread may appreciate the synopsis


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## fppf (Dec 18, 2009)

All Set


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## Linger (Dec 18, 2009)

Looks great


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## AaronM (Dec 18, 2009)

With the new parts you have, is my light still doable? If so, what performance can I expect?
6 x 17670 = 25.2V battery pack hot off the charger

12~14V vf LED looking to drive at 2.5~3A.


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## fppf (Dec 18, 2009)

AaronM said:


> With the new parts you have, is my light still doable? If so, what performance can I expect?
> 6 x 17670 = 25.2V battery pack hot off the charger
> 
> 12~14V vf LED looking to drive at 2.5~3A.



The driver will be able to do this just fine. However in this case I may need to change some other components out because of the lower drive current.
Let me get the first few built and then I will adjust the circuit for your needs. It may cost a few more bucks because I need to order some other parts. But it will drive just fine, the efficiency will be higher than the 9 amp 3.6 volt version as well.


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## AaronM (Dec 19, 2009)

That's great news!
I was mostly worried about my high battery input voltage: 25.2V

I'd like to re-wire the stock switch to change modes between 1Amp and 3Amps. Is that possble?
Another switch will go in the tail cap for actuall on-off duty.


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## fppf (Dec 19, 2009)

We will figure it out for you


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## heffay (Dec 19, 2009)

In for one these!


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## Nos (Dec 21, 2009)

When you get this working ill take one too


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## fppf (Dec 21, 2009)

Good news folks
Even with the holiday rush UPS delivered a day early!
Everything is here, just need to build up the first board. Stay tuned!


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## FlaCracker (Dec 21, 2009)

You may want to add an 8-9v cut-off to your standard offering for anyone running 3 l-ion cells.

Jimmy


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## fppf (Dec 21, 2009)

FlaCracker said:


> You may want to add an 8-9v cut-off to your standard offering for anyone running 3 l-ion cells.
> 
> Jimmy



No problem, if anyone wants any other ranges as "standard" let me know now. Once I stock up on parts it will be special.


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## Packhorse (Dec 21, 2009)

fppf said:


> No problem, if anyone wants any other ranges as "standard" let me know now. Once I stock up on parts it will be special.



I was thinking of using a 7.4v Li Ion pack.


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## fppf (Dec 21, 2009)

Packhorse said:


> I was thinking of using a 7.4v Li Ion pack.



I think for that pack you want the lowest cut off, 6V which is already in the standard list.


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## paetzi (Dec 22, 2009)

I want to use 3 x 32650 which cut off voltage will there be needed?


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## fppf (Dec 22, 2009)

paetzi said:


> I want to use 3 x 32650 which cut off voltage will there be needed?



7.5 volts

Folks, the cut off voltage you use is based on your battery packs. If you look up the specs for your cells they will tell you what the minimum discharge voltage is. For Li Ion its typically 2.5 volts, for NiMH its typically 1 volt. Then just multiply that number by the number of cells you have. That will give you the lowest operating voltage of the pack without possible damage to the cells.


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## Hetore (Dec 23, 2009)

fppf said:


> Ok to answer the questions:
> 
> This is a true current source. It is a buck topology converter. There will be some ripple current but not much and it will be at a very high frequency. To make a converter handle this much current requires some larger components. All these components tend to be square in shape. So a round board is a little harder. I did some quick layout options and the smallest diameter I can go it 1.2" maybe a little bigger. I will work on that and let everyone know. Board coverage is already VERY high.
> 
> ...




Hello Sir, would this heat-sink work(not melt the leds) for three SST-90 LEDS?

http://www.thermaltakeusa.com/Product.aspx?C=1152&ID=1586

OR THIS:

http://www.arctic-cooling.com/catalog/product_info.php?cPath=2_&mID=108

Thank you very much
[email protected]


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## PhotonFanatic (Dec 24, 2009)

I certainly hope this come to fruition, and when it does, I would like about five of them.


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## monkeyboy (Dec 24, 2009)

fppf said:


> The driver will be able to do this just fine. However in this case I may need to change some other components out because of the lower drive current.
> Let me get the first few built and then I will adjust the circuit for your needs. It may cost a few more bucks because I need to order some other parts. But it will drive just fine, the efficiency will be higher than the 9 amp 3.6 volt version as well.



I see, so it's not possible to have both 1-3A low mode and 7-10A high mode on the same board?


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## fppf (Dec 24, 2009)

monkeyboy said:


> I see, so it's not possible to have both 1-3A low mode and 7-10A high mode on the same board?



I will need to test how stable the lower drive currents will be. That is a 10:1 deranging of the design. I would not drive below 2 amps at all. This is just a function of how this controller works.


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## fppf (Dec 26, 2009)

Well folks, good news
Preliminary testing went good, the board gets really warm but you can still hold on to it. So I estimate operating temperature in free air at 70 degrees to be about 110-115 degrees. This is when driving 9 amps.

More testing is needed and I will keep everyone updated.


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## jamesavery22 (Dec 28, 2009)

I'm in for one as well.


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## ma_sha1 (Dec 28, 2009)

I am in for one too


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## fppf (Dec 28, 2009)

Well folks, good news, bad news.

Good news first, the power drive section looks good and robust. I even over drove it by a bit and nothing blew up. Thermal looks good, even in a housing, though I would not put this in a plastic housing. Checking operating temperatures in your housing will be important. Ambient operating temperature should be able to go as high as 50-60 degrees C without overheating the components.

Now for the bad news, really bad news.
The controller chip specs where written by a sales person. The chip is not controlling the way the specs says it should. After double checking my calculations and the app notes I'm not able to get the control I should be getting. It works, but it has poor current regulation over the input voltage range. Current regulation across output voltage is good. There is also some really funky stuff that happens close to shutdown voltage. The chip probable works fine for much lower current systems, but falls down in this application.

So, where do we go from here.
Well, seeing the very high demand I will put the effort into a custom controller. First steps will be to use one of my demo FPGA boards to write and test a custom control system for the current drive section. Then after I have a good control scheme I will source out a micro and other parts to do custom control. This will also give what many have been asking for in the means of dimming and adjustable current levels.

However, this is going to take some time. I will work as fast as possible and keep updates as the work progresses. The price point could also be in flux. I did not want to use a separate micro because of all the support items it needs, which increase part count, cost, and build times.

If it was easy everyone would do it, right?


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## Fulgeo (Dec 30, 2009)

Hey fppf, 

I wanted to put my vote in and say a 2 or 3 level driver would rock. I have all the parts I need to fashion my SST-90 build now except for the driver. I am really interested in making a SST-90 flashlight that has a low setting of 3.2A and a high setting near the emitter's top of 9.0A. In you last post I think you hinted that you might have to go back to the drawing board as it were. You going to dust off that idea you had of using a pic chip? Also not to infer the obvious as inspirational but if you have already purchased alot of the components for the earlier design that you can not use now perhaps you could de-tune the design to drive the SST-50? Not sure of the demand but food for thought. Anyhow wanted to tag this tread and follow it. Good stuff!


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## fppf (Dec 30, 2009)

I have not had to totally redesign. The power drives are good, I actually cranked 15 amps through them and they held good, but hot.

Using a micro poses a lot of challenges due to sizing and costs. The controller I wanted had everything on one package and was reasonable priced. With a micro you need regulators, op amps, Mosfet drivers, and a whole slew of other support components. Each one of those will push cost up, and board space was already a problem.

I never buy lots of parts until I know a design is proven to work. So I don't have many wasted parts. I do have a bunch of boards, but I will just need to eat that. I will see if I can adjust the current design to work for the SST-50. The controller might be stable with some adjusted parts.

I'm still working on interfacing with my FPGA board. I use this because its faster to develop on. Then I can move into a micro if I can find one that fits the mold.


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## HarryN (Dec 31, 2009)

Hi - I have been quietly following your progress. Now that the original controller has failed - would you mind telling us which one it was ? If not, it is ok - I can understand the value of your effort.

Thanks

HarryN


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## fppf (Dec 31, 2009)

HarryN said:


> Hi - I have been quietly following your progress. Now that the original controller has failed - would you mind telling us which one it was ? If not, it is ok - I can understand the value of your effort.
> 
> Thanks
> 
> HarryN



Sure, in hopes to avoid someone else wasting there time. LM3409


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## HarryN (Jan 1, 2010)

Thanks for the info. While I applaud your effort to pull this off - I am amazed at the extent required. A custom FPGA design for a driver? - wow.


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## fppf (Jan 1, 2010)

It does not need an FPGA.
I'm a systems integrator by trade, I have demo FPGA boards laying around. So the simplest way for me to prove out a control design is to use one of these boards and the many routines I have already developed.

After the design prove out I will move the code into a micro for the final project. The control is pretty simple, which is why I'm very surprised that controller did not work well. I guess it would be ok if your input voltage range was really small and you had external drop out control. It did function and it did drive the circuit, just not to my liking.


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## blesbok (Jan 1, 2010)

Interesting... I also have a design for a bike light controller based on the 3409 (Vin = 15-21V, Vout ~13V @ 1A) and I'm just about to order a few boards. I also have a small micro for voltage/temp monitoring, strobing, etc. Based on your experience, do you see any obvious issues with this scenario?

I also recently used a 3409 eval board in a dive light (Vin = 21-29V, Vout ~19V @1A) and it seems to work well, but to be honest I haven't actually _measured_ the line/load regulation.


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## fppf (Jan 1, 2010)

Its hard to say.
Your trying to use the chip more in lines of the data sheets. I was trying to get high drive currents at low Vf. I think my problem was with the usage of Vf to control the constant off time like the refrence designs depict. I tried using a steady reference voltage and it made the chip behave much better. But it still was not to my liking.

I find if you stay close to the data sheet examples most things work (except for maxum, there sales staff write data sheets). I designed a the circuit to meet all the noted parameters but I think there are a lot of little details they left out which is causing the instability.


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## fppf (Jan 14, 2010)

Folks
Just an update...
I think I found parts for a new control set. I will be ordering some parts for prototype and will go from there.


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## stub (Jan 14, 2010)

:twothumbs


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## Techjunkie (Jan 14, 2010)

subscribed


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## paetzi (Jan 20, 2010)

Any new information about your project?
What´s going on?


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## fppf (Jan 20, 2010)

Yes
I have new parts selected for a new controller. I'm working on the drawings and will place an order for some prototype work soon. The power drive section of the circuit worked good. The circuit was able to drive the full 9 amps and stay cool enough to still touch without getting burned.

I have not had as much time to work on this lately, real job comes first.
I will keep you posted.


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## SUBjohan (Jan 20, 2010)

fppf said:


> Yes
> I have new parts selected for a new controller. I'm working on the drawings and will place an order for some prototype work soon. The power drive section of the circuit worked good. The circuit was able to drive the full 9 amps and stay cool enough to still touch without getting burned.
> 
> I have not had as much time to work on this lately, real job comes first.
> I will keep you posted.



If you need someone to do some testing (temperature/efficiency) I am happy to do so.
I have all test equiptment available (all calibrated of course)

Greetz Johan


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## fppf (Jan 20, 2010)

SUBjohan said:


> If you need someone to do some testing (temperature/efficiency) I am happy to do so.
> I have all test equiptment available (all calibrated of course)
> 
> Greetz Johan



Thanks for the offer
I do have all the equipment needed. But after seeing the performance of the controller through the whole input range and being able to still hold the board after extended operation I did not continue testing beyond that. Efficiency was in the low 80% range as I thought it would be. The new design maybe a little better but not much. Just the nature of the beast when your driving high currents at low voltages.

Maybe after the development is done I can send some people boards for some independent testing and reviews.

Trying not to get you guys all worked up with flashy pictures and data from a circuit that kinda works but not really well. This is a tall order even with the most advanced parts today. It's easy if you had a bigger package, but the density is the issue.


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## parawizard (Jan 21, 2010)

I have attempted a build with a LM3409 IC. First iteration didn't work :sigh:! Working on the second one now as I am waiting for my IC's in the mail....


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## SUBjohan (Feb 5, 2010)

Any news on this one??


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## fppf (Feb 5, 2010)

I just finished the new schematics last night and should be ready to order parts for the first prototype over the weekend.

I did some preliminary board layouts to see if the new design will fit. Everything should fit on a single board still. The thickness may increase by about 0.25" and the diameter will be 1.28" max, still smaller then a D cell battery. Don't know about costs yet.


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## RAYtechdiver (Feb 12, 2010)

So ... any news on your prototype? Impatiently waiting over here ... Cheers ...


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## fppf (Feb 12, 2010)

Not yet, been slammed at work and some personal stuff as well.
I will keep you posted.


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## SUBjohan (Mar 7, 2010)

Any news / update??

Greetz Johan


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## Fulgeo (Mar 20, 2010)

Any news?


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## lucca brassi (Mar 20, 2010)

It is funny thing when I look all those small drivers here on CPF and see used elements and study how such big current flow through :thinking: and try to keep them cold.

That coil is for current up to 12A , working between 9-10A. Wire has dimension 5mm x 0,75mm / 100kHz ! for CC driver .


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## fppf (Mar 29, 2010)

Sorry guys
Dive season is coming up fast on me, I have been traveling for work, and the wife is waving the honey do list at me.

I still have yet to order parts.

Some comments, you don't want to use parts that are just rated for what you want to do. If you read the specs and put 100% of rated current through devices they get HOT, and FAST. You can save your self a lot of headaches over sizing stuff as much as you can. Designs of boards and heat sinks is also very important, this stuff is not for the faint of heart. You can get something that may work for a while, or in free air. But getting it to stay cool in a can with other stuff around it making heat is the trick.


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## painfreak76 (Apr 3, 2010)

Any news yet? I'm waiting on this drive circuit for my 6-D NiMH mag.. 7.2v with 6v cutoff..

I'll happily take a board for real-world testing
:twothumbs


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## HopeIt Works (Apr 9, 2011)

@ fppf
Any news & progress on the SST driver project?


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## rafa_mazali (Jul 9, 2011)

look's like another project died.. thats a shame.. we need goog drives for our sst-90.. my one its not in use due this issue..... :shakehead


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## HarryN (Jul 9, 2011)

Yes, well I can tell you from personal experience that good quality driver electronics are expensive to develop. I have one going for some time (different application than this one) and have over $ 1 K and lots of time in it so far. It's hard to even break even on the parts + build cost, the development cost is just part of the hobby fun. Even then, most people just used LDO type boards due to price.


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