# DX Driver Board Tests - Efficiency Results Included



## eprom (Nov 12, 2009)

Update : 

*10/06/2010 **- DX *1.5V~4.2V 3W Step-Up (Boost) Driver SKU.25505, Test results at post #79
*02/08/2010 **- DX *5V~8.4V 15W 5*Cree* Step-Up *Driver SKU.26106 Test [Detailed] at post #46
*11/20/2009 - *I have drawn back the PT4115 chip results for checking them again.
*11/17/2009* - Test Results for 2*, 3*, 4* serial connected XR-E driven with Mr16 1*3W Driver. results on #28
*11/16/2009* - Added efficiency table for Mr16 1*3W Driver (PT4115 Chip) at post #23 

Hi Friends,

I have ordered these DX sku.3256 boards about 40 days ago at last I have received them. Theese were totally revised versions, no more using Zetex C310, uses new chip with lots of advantages. I make some measurments. I have measured standart configuration. Add a 1 Ohm paralel resistor to R27 sense resistor and make some more measurments. 

At standart config board gives a solid 0,91A from 4V to 16V
At hacked config board gives a solid 1.16A from 4V to 16V

+No heat (Also hacked 1.16A config)
+Very solid I out
-Sense resistor eats the efficiency (but also has 90% efficiency)

And measurment table,







Note: I wrote "Efficiency of Board without Sense resistor" this is a wrong expression I think. If we have a chance to use board without Sense resistor (But we can not) and all the power (Pout and Psense) goes to a LED, what would be the board efficiency.

Thanks,
EpRoM


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## VegasF6 (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> Hi Friends,
> 
> I have ordered these DX sku.3256 boards about 40 days ago at last I have received them. Theese were totally revised versions, no more using Zetex C310, uses new chip with lots of advantages.


 
Don't leave us in suspense, what chip does it use now? By the way, the last time I ordered these I think they actually had a C300, but nearly the same.


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## eprom (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

It is hard to say because chip top was sanded.

But my suggestion is AX2002, because I used PT4105 at 1 amp level and efficiency was only 70%. AX2002 datasheet specs are very close to my findings. 

Datasheet of AX2002 = http://www.micro-bridge.com/data/Axelite/AX2002.pdf

Edit: 

I have controlled the Pt4105 and PT4115 datasheets. Neither of them can drive led at ~1A with R27 resistor. Only AX2002 can do this.

PT4105 can drive led ~700ma with R27
PT4115 can drive led ~350ma with R27



VegasF6 said:


> Don't leave us in suspense, what chip does it use now? By the way, the last time I ordered these I think they actually had a C300, but nearly the same.


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## Justin Case (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

I think you have a small math error. Your calculation of Pout is the power draw of the LED, based on Vf*If. That number should not change regardless of what the sense resistor loss is. The LED is still going to draw the same power.

To estimate what the efficiency could be for an ideal sense resistor setup that draws no power, you should subtract Psense from Pin to get the amount of power that the driver would have to deliver without being weighed down by any sense resistor losses.

It is interesting that your measured drive currents of 0.91A and 1.16A are almost exactly what you'd calculate based on the sense resistor formula in the AX2002 datasheet.

Check out KD1640. That driver also uses the AX2002 buck IC.


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## eprom (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi Justin,

System efficiency calculated by Pout/Pin
Ideal System calculated like all the Power (Pout and Psense) goes to an virtual LED. This Pout and Psense feed by Pin at last. Yes you are right but I can not get the measurments/numbers of system without sense resistor so this is the only way I can do.

Thanks for your comments,
EpRoM



Justin Case said:


> I think you have a small math error. Your calculation of Pout is the power draw of the LED, based on Vf*If. That number should not change regardless of what the sense resistor loss is. The LED is still going to draw the same power.
> 
> To estimate what the efficiency could be for an ideal sense resistor setup that draws no power, you should subtract Psense from Pin to get the amount of power that the driver would have to deliver without being weighed down by any sense resistor losses.
> 
> ...


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## Justin Case (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Yes, I know that efficiency is Pout/Pin. What I am saying is that when you calculate your efficiency without the power drain from the sense resistor, your efficiency equation should be Pout/(Pin-Psense), not (Pout+Psense)/Pin.

Pout is a constant. If you have a constant current driver and it sends If to the LED (resulting in a voltage Vf), then Pout will be If*Vf. It doesn't matter if you have a sense resistor power loss or not. Adding Psense to Pout doesn't make any physical sense.

With a sense resistor power loss, the driver has to generate that much more power so that it can deliver Pout to the LED. That means Pin includes the sense resistor power, which reduces the efficiency percentage. By subtracting Psense, you estimate the higher efficiency you'd get if the driver didn't have to generate the extra wattage to feed the sense resistor.


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## eprom (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

I looked like this,

Isense resistor connected serially to the LED so IC work like pushing a LED with 3,61V Vf + 0,25V Isense resistor. I mean system work like pushing a LED with 3,86V Vf at 1.16A. So I used this equation to calculate and this is my point of view.


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## T0RN4D0 (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

So with that in mind, has anyone done the actual numbers?


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## TorchBoy (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Nice work. Could you measure 4 V and 4.5 V input please.



eprom said:


> I have controlled the Pt4105 and PT4115 datasheets. Neither of them can drive led at ~1A with R27 resistor. Only AX2002 can do this.
> 
> PT4105 can drive led ~700ma with R27
> PT4115 can drive led ~350ma with R27


The PT4115 needs over 8 V anyway.


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## Justin Case (Nov 12, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> I looked like this,
> 
> Isense resistor connected serially to the LED so IC work like pushing a LED with 3,61V Vf + 0,25V Isense resistor. I mean system work like pushing a LED with 3,86V Vf at 1.16A. So I used this equation to calculate and this is my point of view.



But what is the source of the feedback pin voltage? Isn't it from the reference voltage built into the IC, with an error amplifier providing the feedback? Hence, this power drain seems to be an inherent part of the driver, not the load. It also seems more traditional, at least IMO, to consider driver efficiency as the ratio of the power drawn by the device/load of interest (the LED) to the power drawn by the driver. It would seem less sensible to include other sources of power draw in the numerator. Also, if you are considering a hypothetical driver that doesn't burn any wattage in the sense resistor network, then shouldn't you be subtracting off that wattage, not adding it in, when making that efficiency calculation?

Either way, the difference in the calculated efficiency is small. Just trying to use the right formula.

BTW, do you have a photo of the driver?


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## eprom (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi TorchBoy,

The board starts to regulation at ~0,5V over the Vf. 

At 4,08V board start to hold regulation for my sample.

EpRoM



TorchBoy said:


> Nice work. Could you measure 4 V and 4.5 V input please.
> 
> 
> The PT4115 needs over 8 V anyway.


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## TorchBoy (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> The board starts to regulation at ~0,5V over the Vf.
> 
> At 4,08V board start to hold regulation for my sample.


Ooh, that's nice. Thanks for checking that. I wonder how low it'll go. Do you have any LEDs with a lower Vf? And will it happily drive more LEDs at once?


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## eprom (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

I am using it with Cree MC-E parallel wired, Vf= 3,10V @1.16A on 4D maglite. Input is 5.3V 0,77A with Energizer D size Alkalines.

EpRoM



TorchBoy said:


> Ooh, that's nice. Thanks for checking that. I wonder how low it'll go. Do you have any LEDs with a lower Vf? And will it happily drive more LEDs at once?


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## TorchBoy (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Sounds ideal. When will that setup drop out of regulation? Will 16 V input drive the four dice in series?


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## Justin Case (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



TorchBoy said:


> Do you have any LEDs with a lower Vf?



I have a KD1640 (another AX2002-based buck driver) order in-transit and plan to test it on an XP-G R4. On another XP-G R4 driven by 3xAMC7135, I measured Vf ~3.1V (tx101 also measured 3.1V when using an SOB1000). With an SOB1227 (1196mA measured drive current), I got Vf ~3.3V.

I have another AX2002-based KD1640 driver that's mod'ed to deliver 1400mA, and it runs a 2S2P MC-E in regulation at ~7.0V in (Vf ~6.2V). In comparison, an SOB1227/2S2P MC-E reaches regulation at ~8.1V (Vf ~6.3V) and an SOB1000/2S2P MC-E reaches regulation at ~7.6V (Vf also ~6.2V). The SOB1227/MC-E case seems anomalous -- not sure why the voltage overhead is so high. The SOB1000/MC-E overhead seems in-line with what I'd expect.


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## TorchBoy (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Is the overhead related at all to the drive current or the number of LEDs driven? Or is the overhead fixed? I wish I had a better test bed.


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## Justin Case (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

The overhead probably is weakly/moderately dependent on drive current, to the extent the "parasitic" voltage of relevant components depends on current. For the SOB, I think that the two biggest drivers are 1) the buck IC duty cycle is not 100% (it's 87% max), and 2) the Schottky diode forward voltage spec is relatively high at 0.5V. For example, for voltage overhead component #1, the dependence of the voltage overhead on drive current is through the resultant LED Vf. The voltage overhead = Vf/0.87 - Vf ~ 0.15Vf, and Vf increases as drive current increases.

I re-tested the SOB1227/2S2P MC-E setup and it looks like I get full regulation at about 7.7V, not 8.1V. This new value seems reasonable to me. Not sure what the reason is for the discrepancy, other than I did re-work the solder joints to the MC-E a while ago. The Vf I reported above was measured after the re-work but the bench power supply testing was done before the re-work. So maybe the solder connections to the LED were not optimal, resulting in a high contact resistance.


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## Aircraft800 (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

I thought you were talking about this one
SKU 26110 18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) ?





Which one is the R27 sense resistor? ^

I thought it was the new Kennan replacement?


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## TorchBoy (Nov 13, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



Aircraft800 said:


> Which one is the R27 sense resistor? ^


The one marked R22.


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## eprom (Nov 14, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

The board I have tested is http://www.dealextreme.com/details.dx/sku.3256

You can see the R27 on this photo
http://www1.dealextreme.com/productimages/sku_3256_3.jpg




Aircraft800 said:


> I thought you were talking about this one
> SKU 26110 18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) ?
> 
> 
> ...


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## Aircraft800 (Nov 14, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Thanks, I didn't know the resistors numbering all started with a "R". How do determine the Ohm value? Is the numbering value R27 a .27 Ohm? What would a 1 Ohm say 1R? So now you have total of a .21 Ohm sense resistor?

I'll have to see if the local Radio Shack carries them for a little upgrade. 

Thanks for the help! (sorry, been away from electronics since college)


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## VegasF6 (Nov 14, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



Aircraft800 said:


> What would a 1 Ohm say 1R? So now you have total of a .21 Ohm sense resistor?


 
Wouldn't that just make too much sense (hah)
I think it depends on the manufacturer some. Here is a chart from vishay.
http://www.vishay.com/docs/20020/smdmark.pdf
See, it depends on the tolerance, at least in there case.
http://www.talkingelectronics.com/ChipDataEbook-1d/html/SM-Resistors.html


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## eprom (Nov 15, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi Friends,

I got theese boards from postal service and make some measurments. First batch of theese boards has PT4105 chip, now has PT4115 chip.

MR16 1*3W Driver, using PT4115 chip. (Don't forget this design have rectifier diodes to work on AC/DC applications. Theese diodes eat efficiency a little)

Results Drawn back until checked and confirmed again.

Thanks, 
EpRoM


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## TorchBoy (Nov 15, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Thanks again for these results eprom, but can you *please* test to lower voltages? Enquiring minds want to know just when it drops out of regulation, and how. Is it sudden or gradual?

Does the efficiency improve running multiple LEDs? Have you seen any with the EQB8L chip?


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## eprom (Nov 16, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

It starts regulation at 6.5V and 0,45A. Under 6.2V board does not work.

I Will measure the performance for 4 LED setup.



TorchBoy said:


> Thanks again for these results eprom, but can you *please* test to lower voltages? Enquiring minds want to know just when it drops out of regulation, and how. Is it sudden or gradual?
> 
> Does the efficiency improve running multiple LEDs? Have you seen any with the EQB8L chip?


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## TorchBoy (Nov 16, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

:twothumbs


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## Mitica (Nov 16, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



Aircraft800 said:


> I thought you were talking about this one
> SKU 26110 18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) ?
> 
> 
> ...



I've burned 2 of those with 16v input :thumbsdow. They are rated for 18v. It seems that the yellow capacitor that sits in between chip and inductor was turned in ash. Seems that both capacitors are identical, so I hope I could still make a working one from 2.
Does anyone know the value of those? it saids on it S 160C
Thanks


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## eprom (Nov 17, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi, Like I promise I complete the tests for 2*, 3*, 4* serial connected LED's driven by PT4115

Results,

Results Drawn back until checked and confirmed again.


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## TorchBoy (Nov 17, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Here's a random thought. The spec sheet of the SS14 Schottky diode (which is used for rectifying in the EQB8L version of the DX SKU.13577 driver I have) has a Vf just over 0.4 V at 0.45 A. Two in the rectifier make 0.8 V, which at the peak efficiency an input current of 0.45 A will be 0.36 W, so 4.2% of the input power is being dissipated in the rectifier. 97.26% + 4.21 % = 101.47%. That's the sort of driver efficiency I like! 

But seriously, I have no idea what's going on there. Thanks heaps for those test results, eprom.


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## eprom (Nov 17, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi TorchBoy,

I am using a Laboratory DC Power Supply,






Problem with this Supply is Amp. Meter has only two digits after dot and Volt Meter has only one digits after dot. So when I make a amp. measurment like 1.69A it could be 1.685A, 1.689A or 1.694A. And when I make a volt measurment like 4.0V it could be 3,95V~4,04V So it has a faulire rate on measurments. And it is effective on small measurments under 1A. But this is the best I can do. I dont have an amp. meter has an three digits after dot. 

I wish this would be acceptable. 
EpRoM




TorchBoy said:


> Here's a random thought. The spec sheet of the SS14 Schottky diode (which is used for rectifying in the EQB8L version of the DX SKU.13577 driver I have) has a Vf just over 0.4 V at 0.45 A. Two in the rectifier make 0.8 V, which at the peak efficiency an input current of 0.45 A will be 0.36 W, so 4.2% of the input power is being dissipated in the rectifier. 97.26% + 4.21 % = 101.47%. That's the sort of driver efficiency I like!
> 
> But seriously, I have no idea what's going on there. Thanks heaps for those test results, eprom.


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## Justin Case (Nov 17, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

What you can do is turn the voltage dial ccl until you reach the min range (e.g. 3.95V, where the display fluctuates between 3.9V and 4.0V). Then turn cl to find the max range (e.g., 4.05V, where the display fluctuates between 4.0V and 4.1V). Finally, put the dial in the middle. Hopefully, the voltage value for the middle dial setting is close to 4.0V.


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## eprom (Nov 17, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

If I make a new test, I will keep in mind? This is a brilliant idea. 



Justin Case said:


> What you can do is turn the voltage dial ccl until you reach the min range (e.g. 3.95V, where the display fluctuates between 3.9V and 4.0V). Then turn cl to find the max range (e.g., 4.05V, where the display fluctuates between 4.0V and 4.1V). Finally, put the dial in the middle. Hopefully, the voltage value for the middle dial setting is close to 4.0V.


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## Justin Case (Nov 18, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Built an LED Turbo Tower for use in SureFire TurboHeads.

I'm a little disappointed with the KD1640 driver that I used. Ordered six of them and this is the only one I've used so far. Driving an XP-G R4, which also underperforms compared to some other XP-G R4s I've gotten.

The KD1640 delivers about 1.05A, so that's good. Right in line with what you'd expect based on the sense resistors.

The first disappointment is that the XP-G R4 Vf ~ [email protected] True that this is basically in agreement with what is in the datasheet. But I had previously measured about 3.1V for another XP-G at essentially the same drive current. Hot spot lux at 1 meter is also about 10% lower vs the same XP-G with Vf~3.1V. Measuring the XP-G die height is difficult, but the two towers look to be the same within 0.003", so I don't think LED focus is the issue. The reason might be due to LED lumens variation in the R4 bin.

The second disappointment is that the KD1640 seems to have lower efficiency than expected -- about 80%-83% vs the expected ~90%.

The third disappointment is that the KD1640 seems a little unstable for Vin of about 5.0V +0.3V/-0.2V. Power-in takes a repeatable dip starting at about 4.8V, hits the bottom of the dip at 5.0V (~15% drop in power-in), and finally returns to the steady state value at about 5.3V. At least for this specific driver board, using 2x123A might be less desirable than 2x16340 Li-ion. The Power-in vs Voltage-in curve is otherwise reasonably flat when running in regulation (I measured out to 12V).

The last disappointment is that the KD1640 voltage overhead is slightly higher than expected at about 0.7V. Still reasonably good.


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## Ekke (Nov 20, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> Hi, Like I promise I complete the tests for 2*, 3*, 4* serial connected LED's driven by PT4115
> 
> Results,
> 
> http://dosyalar.ledcozum.com/CPF/Efficiency_3W_MR16_Serial.jpg



Thanks for those.. But have you measured the output current? Small change, but you have so many digits in your numbers.  

From PT4115 datasheet:





I made diy-version today, I will measure the prototype tomorrow if everything goes well.. Currently running @ 1.13A with one led and 12V lead acid battery. About 76% efficiency.


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## eprom (Nov 20, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Waiting for your Results,

You are right I have not measured the amperage for every voltage change. For AX2002 it was very rigid so I think like AX2002 test when making PT4115 tests, I measured the LED current once and don't care about it again. You catch it well, thank you for your carefulness. I am drawing back my results for PT4115 chip. I will control them again when I have spare time.

Thank you,
EpRoM



Ekke said:


> Thanks for those.. But have you measured the output current? Small change, but you have so many digits in your numbers.
> 
> From PT4115 datasheet:
> 
> ...


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## Ekke (Nov 20, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> Waiting for your Results,
> 
> You are right I have not measured the amperage for every voltage change. For AX2002 it was very rigid so I think like AX2002 test when making PT4115 tests, I measured the LED current once and don't care about it again. You catch it well, thank you for your carefulness. I am drawing back my results for PT4115 chip. I will control them again when I have spare time.
> 
> ...



I used cheap multimeters, so ±5% at least? Measured output voltage and amps, input voltage and amps I read straigh from the power supply. Measured in 1V steps, here's some graphs with a little filtering where you can get the idea: Efficiency and Current vs. voltage & leds. 

Leds were XP-E, XP-G, 2x XR-E & 2x P4.  0.0825 Ohm theoretical R_sense so should be about 1.2A current. There were quite long and thin wire mess and not enough heatsink so it was pretty hard to measure because of heating so those isn't so accurate. Enough for me though, there seems to be consistent behavior. Datasheet says those should be like this @ 770mA. 3 LEDs are pretty close. 

Your numbers were quite similar? Pretty good at higher voltage and >=4 leds, I think I will run those @ 27V with 4 leds.


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## TorchBoy (Nov 20, 2009)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Interesting that the 3 LED lines should be so close but the 1 LED lines aren't. Thanks for posting those.


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## Paul Baldwin (Jan 2, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi Eprom,
I'd just like to say thanks for posting the info on the ax2002 driver  I ordered some, ignoring the title (which still hasn't been updated) and have tried one out on a 12 volt supply. I connected it to an xpg r4 and ran it for 5 hours straight with no additional heatsinking to see if it would cope. It certainly gets hot but didn't flicker or fail. All 4 are now glued to the back of their respective heatsinks before I potted them, hopefully they'll be ok. I'd been looking for a cheaper higher output than the MR16 12+volt capable driver for a while.

Paul.


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## TorchBoy (Jan 2, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

BTW, it's quite easy to change the set resistor on AX2002 drivers, including the MR16 drivers. The EQB8L driver chip used on some of the MR16 drivers I think doesn't do very well at higher current levels though, but those that use the AX2002 do just fine.


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## Paul Baldwin (Jan 3, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Ta for that, I might try it next time I buy some 

Paul.


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## purduephotog (Jan 5, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



TorchBoy said:


> Interesting that the 3 LED lines should be so close but the 1 LED lines aren't. Thanks for posting those.



You're modifying the driver to run 3 LEDs? Do I understand that correctly? What else did you modify from there to get it to handle the higher output voltage?


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## TorchBoy (Jan 5, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

I don't think they have to modify anything. That's one reason why these drivers are very nice to use.


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## purduephotog (Jan 7, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



TorchBoy said:


> I don't think they have to modify anything. That's one reason why these drivers are very nice to use.



Errr, the graphs were for the chips- but that didn't mean to me the components were capable of it.

But if they are.... then I'm going to be buying quite a few of these and using transformers to power devices.


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## TorchBoy (Jan 7, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



purduephotog said:


> Errr, the graphs were for the chips- but that didn't mean to me the components were capable of it.


You quoted me making a comment about the comparison graph linked by Ekke in post 36. Where did you get the idea that he removed the chip from its driver board to test it separately?


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## purduephotog (Jan 10, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



TorchBoy said:


> You quoted me making a comment about the comparison graph linked by Ekke in post 36. Where did you get the idea that he removed the chip from its driver board to test it separately?



That's what I was trying to understand- whether he had or not. Some statement was made about testing a prototype...

Think of it as just being sure what was happening before I go drop some $$ on something else. Too few $ for too many projects.

Please accept my apologies if you were offended or if it sounded like I was questioning your results- I was just trying to follow everyone's discussion and understand it in my limited way.


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## eprom (Feb 8, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi friends,

I was waiting for this driver to test and use. DX Step-Up Driver for 5*Cree 


** First Test for ~600ma current output with 0,82 Ohm Rsense*
* Various voltages used for test, from 3V to 8V









** Second test for higher current output ~1100 ma with 0,45 Ohm Rsense*

- Trying lower voltages gives upto 4 amp input so I have tried for 5V to 7V and ~2.5A input. I have tested 2*Cree 3*Cree and 4*Cree








** Third test for Higher Voltage and Stability with 0,5 Ohm Rsense (~950ma Iout)*

* I have paralled two 1ohm resistor and used as sense resistor.
* I have tested upto 12.5V for 3* Li-Ion use
* I have made a long term run test for 30 minutes. Driver does not cooled and trapped in a little box for mag tube simulation. Driver was very hot to tuch but also efficient at that point.







...


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## stinky (Feb 16, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi eprom:

Would you please explain this configuration in more detail for those of us who don't quite follow your mod (me).

I'm considering using this board to drive 3 serial XP-G R5s. If I read your second test correctly, I'm thinking 5 1/2D NIMHs would yield 6-7v in a 3D host, and 1-1.1A at 10.5v? So each would get 1-1.1A and 3.5v? Seems like a good match.

Also, any thoughts on how to heatsink this bugger? BTW, I saw your posts on the DX board as well.

Thanks!



eprom said:


> Hi friends,
> 
> I was waiting for this driver to test and use. DX Step-Up Driver for 5*Cree
> 
> ...


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## eprom (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi stinky,

Sense resistor placed here,






On my batch, there is two 1205 package resistors paraleled. One has R82 and One has 4R7 value. For 1.1A mod I have replaced the 4R7 with 1R0 

Wish Helps,




stinky said:


> Hi eprom:
> 
> Would you please explain this configuration in more detail for those of us who don't quite follow your mod (me).
> 
> ...


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## TorchBoy (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hey eprom, you've posted results for a boost board in a thread about buck drivers. Do you feel like starting a new thread for it?


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## eprom (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi TorchBoy,

I wish a moderator change the title,

Like: DX Driver Board Tests, or something like that. 

This helps keeping measurments together,



TorchBoy said:


> Hey eprom, you've posted results for a boost board in a thread about buck drivers. Do you feel like starting a new thread for it?


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## SilverFox (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hello Eprom,

I added "Test Results Included" to your title.

Tom


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## eprom (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Thanks for your help SilverFox,



SilverFox said:


> Hello Eprom,
> 
> I added "Test Results Included" to your title.
> 
> Tom


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## TorchBoy (Feb 17, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Tom, the thread is still badly named if it included test results for both buck and boost boards, and isn't exclusively about one particular Kennan-like buck board any more. "DX Driver Board Tests" would be quite good.

Eprom, can't you change the title of your first post yourself? (Isn't that where the thread title comes from?)


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## Black Rose (Feb 21, 2010)

*Re: DX Driver Board Tests - Efficiency Results Included*



eprom said:


> I have ordered these DX sku.3256 boards about 40 days ago at last I have received them. Theese were totally revised versions, no more using Zetex C310, uses new chip with lots of advantages.


I recently recieved the same sku boards.

How can you tell if they use the Zetex board or the AX2002 chip?

Mine look exactly like the product pictures on the DX site.


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## eprom (Feb 22, 2010)

*Re: DX Driver Board Tests - Efficiency Results Included*

Hi Black Rose,

Product pictures shown on DX is AX2002 chip version. 

Wish Helps,



Black Rose said:


> I recently recieved the same sku boards.
> 
> How can you tell if they use the Zetex board or the AX2002 chip?
> 
> Mine look exactly like the product pictures on the DX site.


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## aurum (Feb 22, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

Hi ...

Which chip/IC is used in DX Step-Up Driver for 5*Cree?

thanks


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## eprom (Feb 22, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

Hi aurum,

Sorry but the chip surface was sanded so It is impossible to identify.

But, The only step-up chip I saw on http://www.micro-bridge.com/ with 0,5Vfb was,

http://www.micro-bridge.com/data/Feeling-tech/FP6201.pdf

Wish Helps,
EpRoM




aurum said:


> Hi ...
> 
> Which chip/IC is used in DX Step-Up Driver for 5*Cree?
> 
> thanks


----------



## aurum (Feb 22, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

Thanks eprom .... btw do you now the ic which is used in der Wichtel driver?


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## aurum (Feb 26, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

Just another question ... do you know how to modify the driver so that it accepts higher input voltage of 12.6 or 16.8V? thx


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## paulr (Feb 26, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

hi,i just saw this thread. Nice! Do any of these boards have an external PWM input? thanks.


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## alex_g2k (Feb 28, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*

hello guys. i'm messing with this driver DX Step-Up Driver for 5*Cree to use in a Mag 6D mod. i want to disable modes, but haven't found the solution yet. could anyone please tell me what i should shunt to disable PWM dimming? i've already tried to connect bat "-" and led "-", but it didn't work.


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## Black Rose (Mar 21, 2010)

I built a P60 drop-in using sku 3256 today (driving a Neutral White Rebel 90).

I noticed that it has a slight flicker when first turned on and it also whines a bit.

Is anyone else getting this with their sku 3256?

The odd thing I have noticed is that if I put more pressure on the tailcap, the whine changes pitch. 
I need to check my solder joints to make sure they are solid connections.

EDIT: I am only getting 0.6A draw at the tailcap with an 18650. I was expecting more since it's supposed to be an 800 mA driver.


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## Justin Case (Mar 22, 2010)

What do you mean "when first turned on"? Do you mean when you first press the flashlight tailcap button, you see a flicker? Or do you mean when the LED first lights up when presented with the minimum input voltage for turn-on?

I'm driving a Cree XR-E P4 with my DX3256 and the LED first turns on at about 3.34V, and there is some flicker. But if you give the driver essentially full power, the XR-E runs fine.

I don't hear any whine from my DX3256 driver.

You are getting about 0.6A tail current draw from 1x18650 probably because you are feeding the driver about 3.9V under load and are not running in full regulation. The driver has a voltage overhead of about 0.5V-0.7V to reach regulation. What is your Rebel's Vf? If the Vf at the rated drive current is around 3.5V, then 1x18650 is going to be borderline.

The drive current should nominally be 925mA, not 800mA.


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## Black Rose (Mar 22, 2010)

Justin Case said:


> What do you mean "when first turned on"? Do you mean when you first press the flashlight tailcap button, you see a flicker?


Yes, when the tailcap is turned on.



> You are getting about 0.6A tail current draw from 1x18650 probably because you are feeding the driver about 3.9V under load and are not running in full regulation. The driver has a voltage overhead of about 0.5V-0.7V to reach regulation. What is your Rebel's Vf? If the Vf at the rated drive current is around 3.5V, then 1x18650 is going to be borderline.


The data sheet indicates a typical Vf of 3.15V with a maximum of 3.9v.

I'll try it tonight with a pair of CR123A primaries.
I sold all of my 16340 cells a couple of weeks ago, so I have nothing to use other than 17670/18650 Li-Ions and CR123A primaries.


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## Justin Case (Mar 22, 2010)

Black Rose said:


> The data sheet indicates a typical Vf of 3.15V with a maximum of 3.9v.
> 
> I'll try it tonight with a pair of CR123A primaries.
> I sold all of my 16340 cells a couple of weeks ago, so I have nothing to use other than 17670/18650 Li-Ions and CR123A primaries.


 
I think that the datasheet Vf spec is for 350mA drive.


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## Black Rose (Mar 22, 2010)

Justin Case said:


> I think that the datasheet Vf spec is for 350mA drive.


Yes, it's at 350 mA.

Does the Vf of LED increase or decrease as the current applied is increased?


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## Justin Case (Mar 22, 2010)

Vf goes up with increasing drive current. The datasheet has a typical curve of If vs Vf. At ~900mA, typical Vf is about 3.45V.


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## Black Rose (Mar 22, 2010)

I have to learn to read those data sheets better


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## Black Rose (Mar 22, 2010)

OK, it appears to be a voltage issue.

When using 18650 cells (3.9v & 4.09V) the light flickers and whines.

When powered by a pair of CR123A primaries (5.88V OCV) there is no flickering or whining. 

Current draw at the tailcap is around 670 mA with a pair of primaries.

Not the results I was expecting with these drivers.
Back to the drawing board...


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## Justin Case (Mar 22, 2010)

I don't know about the flicker and whine, but the 0.67A when driven by 2x123A is entirely consistent with what I've measured for my DX3256. For a measured ~85% efficiency, assuming a Vf of about 3.5V, an If of about 0.9A, and a Vbatt of about 5.5V, you get an Ibatt of about 0.67A. What a coincidence.


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## Black Rose (Mar 22, 2010)

So basically even though these circuits are advertised as 3.6-9.0v, they aren't much use for single cell Li-Ion use, since they won't be fully regulated for long, or at all.


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## Justin Case (Mar 22, 2010)

Since when is a DX claimed spec worth anything? Further, there is no standard by which a vendor has to define the operating voltage range. Is the lower limit when the LED turns on, when the drive current is 1/2 of the rated value in regulation, when the driver reaches full regulation (for what LED Vf?), or something else? We don't know.

Did you even read Post #1 that discusses the DX3256 driver:

"I have ordered these DX sku.3256 boards about 40 days ago at last I have received them. Theese were totally revised versions, no more using Zetex C310, uses new chip with lots of advantages. I make some measurments. I have measured standart configuration. Add a 1 Ohm paralel resistor to R27 sense resistor and make some more measurments. 

At standart config board gives a solid 0,91A from 4V to 16V"

The DX3256 that you get is different from the one shown on the web link. So any operating voltage claims made in the web link should be considered null and void. The driver you got doesn't even use the same IC controller chip.

Did you also read Post #11, which stated that the voltage overhead to run in regulation is about 0.5V? If your have a Vf of ~3.5V, then guess what? You are going to need about 4V min to reach full regulation and 1xLi-ion is probably not a good choice for your batt configuration.

If you use a low Vf emitter like an XP-G, you'll have a much better chance of comfortably reaching regulation with 1xLi-ion. Basically, you want a Vf of no more than 3.2V at ~900mA drive.


----------



## sandysim (May 18, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*



eprom said:


> Hi friends,
> 
> I was waiting for this driver to test and use. DX Step-Up Driver for 5*Cree
> 
> ...



Hi guys, I received 3 sku26106 a couple of days back and was testing it using 3 cree xre r2s, wired in parallel and series with a regulated DC 30V-3A power supply. Worked fine until I increased the input voltage to 12V. (Note: I haven't changed any components on the board)

Results as follows:
3 xre-r2 in parallel 
Input 7V 1.85A
Output 4.32V 1.97A

3 xre-r2 in series 
Input 8V 1A
Output 9.92V 0.75A

3 xre-r2 in series 
Input 12V 1.1A
Output 10.77V 1.26A 


For the high power tests, I tested each unit one after another (as a form of QC check, given my experience with DX stuff). 1 unit started to smoke after a couple of minutes The board wasn't totaled, seems like the solder of the resistor melted and caused it to be open circuit. When I physcially pressed the resistor down, the driver worked as normally. In a second unit, I detected a smoky odour and stopped testing. This is the unit that had the melted solder. 






the underside






I have not checked the 2nd unit for the source of the smoky odour yet.
Will report further after testing the other 2...when I have more time.

I'm just a mechanical engineer dabbling in electronics, so would like to seek some advice if this unit can be recovered, i.e resolder the resistor...does the board (edges looked burnt) or resistor look like it should be replaced?







cheers

Sandy


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## TorchBoy (May 18, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Thanks for that Sandy. Is there some reason you included that lengthy quote?


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## eprom (May 18, 2010)

Hi Sandy,

This driver designed for Boost Topology. So input voltage must be lower than Total LED forward voltage. I see that forward voltage for your 3S LED setup was ~9.9V so you can not feed the board over 9V.

When you feed it with 12V, current flow over LED's seen 1.26A, Power loose on sense resistor was 1.26^2*0,7Ohm=1,12W so this power toasted your Sense Resistor.


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## sandysim (May 18, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Hi Torchboy, long quote was to make it easier for thread readers to follow, given that there are different DX drivers being discussed in this thread.

Eprom, thanks, understood. Question: is it salvageable or a write off. If salvageable, what should I do? My soldering skills are rudimentary, actually very crude. Where can I get a replacement resistor? The ones I've seen are the bigger ones, about 1cm in size with coloured bands.

Any advice appreciated.

Cheers

Sandy


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## eprom (May 18, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency*

Give it a try. You can use 1206 package SMD resistor. Value can be near 0.7 Ohm.

Good Luck.



sandysim said:


> Hi Torchboy, long quote was to make it easier for thread readers to follow, given that there are different DX drivers being discussed in this thread.
> 
> Eprom, thanks, understood. Question: is it salvageable or a write off. If salvageable, what should I do? My soldering skills are rudimentary, actually very crude. Where can I get a replacement resistor? The ones I've seen are the bigger ones, about 1cm in size with coloured bands.
> 
> ...


----------



## purduephotog (May 18, 2010)

*Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency Test Results Included*



alex_g2k said:


> hello guys. i'm messing with this driver DX Step-Up Driver for 5*Cree to use in a Mag 6D mod. i want to disable modes, but haven't found the solution yet. could anyone please tell me what i should shunt to disable PWM dimming? i've already tried to connect bat "-" and led "-", but it didn't work.



https://www.candlepowerforums.com/posts/3342850#post3342850

There you go!

edit: I haven't tested yet, but he had.


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## eprom (Oct 6, 2010)

Hi Friends,

I am back with a gem.

DX sku.25505 I know everybody happy with this driver and there is also reports for efficiency. But nobody pushed the limits for this driver so I am in at this point.

Driver reported to use PAM2803 so I have read the datasheet and find the limit is 950mA drive current for this IC. 

* I have changed the sense resistor (R15) with 100mOhm (R100) sense resistor. 
* I setup an serial connected 2*Sanyo 4400mAh Ni-Cd D size
* Iin measured over 10mOhm shunt resistor (yes paralled two R020)
* Iout measured over 100mOhm 0,1% tolerance shunt resistor

And Results,






Enjoy,


----------

