17mm & 20/26/27mm single-sided DD/FET driver release: A17DD-SO8 / A20DD-SO8 / etc

Not enough difference to be statistically significant.

OT: how do you like the through hole wire vias on the 3.1 driver? I personally would rather have a flat pad to solder to, but I'm wondering what everyone else's opinion is.

The through hole via’s are nice at 22ga, a PITA at 20ga. Forget about 18ga. (Actually, I’ve split the end of 18ga and run each half through a via, works ok, still a PITA. Not pulling any pads off though.)

I like the extra ground via beside the FET ground leg on the A17 board and the big pad is good for soldering the LED - lead to. The middle of the board positive LED lead is a bit on the tricky side though. Not horribly bad but fairly easy to mess up if you jitter instead of jigger. Shimmy instead of shake? You know what I mean….

The microscopic switch+ via on the Ver 3.0/3.1 board is nuts! And the location is tricky as well.

Single sided makes up for a lot of things though, love that aspect! Really makes it easy in a lot of lights, piggybacking too.

Edit: Point being on the comparison…the smaller FET meets or exceeds the performance level of the large 70N03. :wink:

Nice job Dale.

I used a new Panasonic NCR18650BD button top and charged it again after every test. So each “run” started with the cell showing 4.21/4.22V (it must have been like 4.218 or something because my meter, 2 decimal point digits, flickered back and forth between 4.21 and 4.22)

………A17DD-S08……………BLF17DD Ver 3.1
0.01A ——–4.52 lumens……0.01A——–4.55 lumens
0.06A ——22.94 lumens……0.07A——23.08 lumens
0.13A ——51.13 lumens……0.11A——50.34 lumens
0.35A —–148.70 lumens….0.31A—–140.42 lumens
1.15A —–421.59 lumens….1.12A—–400.89 lumens
2.28A —–807.30 lumens….2.36A—–772.80 lumens
4.50A —1455.90 lumens…4.59A—1404.15 lumens

One would think I used 2 of the same everything, they’re so close. I think the A17DD-S08 is doing a fabulous job, and in my triple and quad lights it’s definitely up to the task. :wink:

Thanks again Wight! :slight_smile:

Edit: Notice the low high end amperage, and the resulting lumens output. The new XM-L2 U3 1A’s…

Dale,I think it's simpler to just measure parasitic resistance of each driver.And based on that number you can tell which driver will provide more current on high(if all other factors like battery,led Vf,springs wires are the same).

For DD drivers this is very easy:you need one ammeter and one relatively precise voltmeter,battery or power supply(better),led or resistor as load(not important,xm-l,xp-g...).

Connect driver,led and battery(or power supply) as usual(you don't need host),and ammeter in series for current measurement. At the same time measure voltage(mV range) across driver's "power" connections-GND and led cathode pad.

Parasitic resistance is then: R(par)=U/I

And that's it,repeat the same procedure for other driver(important thing is that it's best to use the same battery at same voltage and same load,because mosfet parasitic resistance Rds, which is dominant part of total parasitic resistance in DD drivers, depends on gate voltage).

You’re saying if I measure the off amperage at the negative end of the cell, and the Voltage between LED negative and ground, then divide which by which to get parasitic resistance?

Touching the LED negative to ground will normally give direct drive, right? So this is where I take a Voltage reading? While taking an amperage reading at the tail?

I’ll either pull the light engine and do this, or remove the bezel and use the host as a holder for the assembly of light engine/cell. I can use my older DMM with short 12ga copper leads to do the amperage reading, my clamp meter with probes hooked up gives very small Voltage readings.

Edit: Is the lower parasitic resistance driver the one that will make the highest power output?

Yes, lowest resistance will give the highest output.

On the A17DD-S08 I get a current of .01 and Voltage of 1.867

On the BLF17DD Ver 3.1 I get a current of .06 and a Voltage of 1.885 ( I think this one skipped moon and the test was on level 2, is that crucial?)

Edit: Was I supposed to be testing on High or does it matter? These numbers come out significantly different…

Ideally you would want to test them both on the highest level, so PWM response isn't a factor.

Back to the drawing board :stuck_out_tongue:

See? If it can be done wrong, I’ll find the way…

Edit: It’s better to grow a few new hands than to enlist my wife for help.

A17DD-S08 shows 4.82A and 30.0mV
BLF17DD Ver 3.1 shows 4.85A and 103.5mV

EditII: So is this A= .16 parasitic drain and B= .05 parasitic drain?

I can’t find the PSMN3R0-30YLD fet anywhere. The shipping from mouser,digikey and farnell is like $30 to Finland :_( Could someone sell me 3?

R=U/I is Resistance=Voltage divided by Current.

So the A17DD-S08 has 6.22ohms of resistance
and the BLF17DD Ver 3.1 has 21.34ohms of resistance

So the A17DD-S08 should have higher capability? Interesting…

First,as RMM said,you must measure current and voltage on highest(no PWM) mode.

Parasitic resistance for first driver is 6.22mOhm (miliOhm) which sounds about right,slightly higher than mosfet Rds;

but something is wrong for 2nd one, 21.34mOhm is too high for that mosfet? Value should be similar to first driver.

For fair comparison,it's important to measure parasitic resistance at same battery voltage,because mosfet's Rds usually starts to grow rapidly at voltages <4V(of course,that depends on mosfet)

My not so able bodied and not so willing partner in crime made it a big issue this morning. Geesh, just wanted a little help! lol

miliOhm huh, I was guessing on the Ohm connection studying Wikipedia on Ohm’s law. lol

I did both repeatedly, the Clamp meter is Auto sensing and gave me Voltage on the first one, then mV on the next and wouldn’t switch over. So I did them each repeatedly, arguing with the cranky wife, we both yelled at the kid, and ultimately I tested them again by myself holding the amperage leads on the cell with my tongue. Now it’s me that’s cranky! Vroooom! I started! Woohoo!

I’ll charge up the cell I used and try again. With peace and quiet the prevalent factor.

I have the A17DD-S08 at 6.3mOhm and the BLF17DD Ver 3.1 at 6.35mOhm.

This is from A= 5A and 31.5mV and B= 4.9A and 31.1mV

A17DD-S08

BLF17DD Ver 3.1

Nice job Dale! Sorry, very busy at work now - no time for BLF during working hours and long days. Was just about to try a Mattaus v1.0 driver in the X6 - not sure if it's worth it now, but using 20 AWG of same exact length each, it will still tell me how they do in the exact setup, same light, same LED, etc.

That’ll be good info Tom, you gonna post a thread on it or where will you let us know how it goes?

And thank you! :wink:

Not a thread - just finished some tests with the BLF17DD v1.0 using the de-domed XP-G2 S2 and got about 0.15A to 0.18A higher, depending on the cell (SAM 25R or LG HE2). Best #'s for each driver:

A17DD-S08: LG HE2 @4.23v: 3.78A @tail

BLF17DD: LG HE2 @4.22v: 3.96A @tail

Same host, same LED (didn't even remove the LED - it's screwed down), same 20 AWG wire lengths for LED wires, same 22 AWG wired driver spring setup (different spring but don't think that should matter), same batteries.

Conclusion:

Well, with just one sample of each, there can be variables I'm sure: quality of reflows, tight driver mount, battery charge differences, FET variations, etc.. Seems slight edge to the old BLF17DD which is kind of what I suspected, but since I only tried one A17DD-S08 up to this point, I can't say anything definite from this - too little data, not enough samples tested, don't 100% trust my methods, measurements, etc. It's not lab level for sure... I would trust djozz more than myself - absolutely Smile.

Several other options are discussed in this thread. Did you look for those? Rufusbduck suggested one I really liked and I think there were a couple of others which sounded OK too.

… so LED Vf is most likely behind your recent troubles.

Thank you and DBCstm both for posting your measurements.