DX Driver Board Tests - Efficiency Results Included

alex_g2k

Newly Enlightened
Joined
Dec 9, 2008
Messages
15
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.
 

Black Rose

Flashlight Enthusiast
Joined
Mar 8, 2008
Messages
4,626
Location
Ottawa, ON, Canada
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.
 
Last edited:

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
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.
 

Black Rose

Flashlight Enthusiast
Joined
Mar 8, 2008
Messages
4,626
Location
Ottawa, ON, Canada
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.
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
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.
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
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.
 

Black Rose

Flashlight Enthusiast
Joined
Mar 8, 2008
Messages
4,626
Location
Ottawa, ON, Canada
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...
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
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.
 

Black Rose

Flashlight Enthusiast
Joined
Mar 8, 2008
Messages
4,626
Location
Ottawa, ON, Canada
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.
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
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

Newly Enlightened
Joined
Sep 7, 2003
Messages
19
Location
Singapore
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

DX.26106.jpg




* 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

DX.26106.1A.jpg




* 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.

DX.26106.12V.jpg



...

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.

SAN_9895.JPG


the underside
SAN_9896_cr.jpg



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?
SAN_9895_cr.jpg




cheers

Sandy
 

TorchBoy

Flashlight Enthusiast
Joined
Jan 15, 2007
Messages
4,486
Location
New Zealand
Re: Newly Designed DX Buck Driver (Kennan Like) 90% Efficiency

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

eprom

Newly Enlightened
Joined
Apr 17, 2007
Messages
146
Location
Turkiye
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.
 
Last edited:

sandysim

Newly Enlightened
Joined
Sep 7, 2003
Messages
19
Location
Singapore
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
 

eprom

Newly Enlightened
Joined
Apr 17, 2007
Messages
146
Location
Turkiye
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.

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
 
Joined
Jul 15, 2007
Messages
590
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.

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

There you go!

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

eprom

Newly Enlightened
Joined
Apr 17, 2007
Messages
146
Location
Turkiye
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,

25505_Efficiency.jpg


Enjoy,
 
Last edited:
Top