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

Wow, thanks for taking the time to make this big writeup djozz. I think it’s full of great insight/perspective for those of us who “know this stuff”. I’ll probably re-read it a couple more times to really get it to sink in.

I couldn’t help but smile when I noticed that you didn’t mention the part # of the Zener, just the effort required to find it. :wink: For others it’s this info:

I can’t explain the behavior of the Zener build with the reverse voltage protection diode in place (it’s not supposed to work, but I’d have expected that configuration to damage the Zener pretty quickly). After placing the 220k resistor I expect that the Zener was unable to drop enough voltage “(current too low)”:What is a Zener Diode | REUK.co.uk and thus the MCU was fried due to the battery voltage.

EDIT: My personal advice would be to discard the MCU and the Zener used in that failed Zener mod and use new components for your next effort. The other components should be just fine.

i thought i for got something in my mouser kart :( CRCW0805200RFKEB,j guess i have to wait for my next order im not going to pay another $5 for shipping

How many do you need? I can send some your way. Those resistors are cheap.

Thanks for providing the zener link, should have done that :-)

Btw, I wrote the story to give a lttle insight in how these builds are for the 'less gifted' ;-) , but it by no means is a plea to do things different than how they are done now. I think all these developements are great!

Nitro remember that the 200ohm resistor is only necessary for Zener builds. Making a driver for an X6 triple doesn’t involve the Zener mod.

Sounds like you had one of MY days!

Get it right and you’ll be amazed at that triple! It’ll all be worth it then!

On a related tangent, due to some of the excitement lately, the Ledil Iris works pretty nice with the MT-G2 in an X6. :wink:

If you make a Quad 2S2P you can use 2 cells with the Zener mod. :slight_smile:

might have a 2x18650 body made for my x6 or 1x26650 i cant decide what i want

So I need both the zener and the 200ohm resistor? I just ordered some zeners from RMM but somehow didn’t catch that I need the resistor too… Ugh

Yes, you must use a limiting resistor or you’ll damage the Zener.

… huh… apparently Radio Shack is selling 20pcs of 200ohm for ~$1 USD… that’s interesting/convenient…

Hmm I pick door #2: radioshack

me too, ill stop by mine and see if they have it and buy 10 and get 50% off since there closing

Is these a good FET for this driver http://www.ebay.com/itm/PSMN1R2-25YL-NXP-MOSFET-N-CH-25V-100A-LFPAK-QTY-5PCS-/271721280721?pt=LH_DefaultDomain_0&hash=item3f43d9b4d1
and
http://www.ebay.com/itm/PH4030AL-NXP-Trans-MOSFET-N-CH-30V-100A-5-Pin-4-Tab-LFPAK-10PCS-LOT-/281542597064?pt=LH_DefaultDomain_0&hash=item418d3f19c8
Also can i use y5v capacitor instead of x5r?

Do not use Y5V instead of X5R. You may use X7R. Which capacitor are you having trouble finding? You should have no trouble with that.

At a glance, either FET looks acceptable to me. On the first page of this thread we talked a little about both FETs you linked to. (At the time I mentioned that PSMN1R2-25YL might not work well with Zener mods, but I don’t remember why. Maybe I was concerned about Qg. Anyway it’s probably fine, I wouldn’t worry about that.)

Yeah i’m not having trouble finding the capacitors, i just want to buy the parts from one seller. the capacitors and FET from the same ebay seller. He has the x5r but it’s 0603 http://www.ebay.com/itm/0603-SMD-Ceramic-capacitor-MLCC-CL10A475KQ8NNNC-4-7uF-6-3V-10-X5R-0603-100PCS-/281542593537?pt=LH_DefaultDomain_0&hash=item418d3f0c01
He doesn’t have the 1uf so i’ll have to find it from other ebay seller.
What is the reason not to use Y5V?

How about this FETs
PSMN1R5-25YL

SIR850DP-T1-GE3

That’s the only FET i find at our local electronics store.

Thanks djozz for the build writeup,
The threshold to really know all the ins and out to know everything needed is very high, i am trying to assemble all the knowledge the last couple of months to get started with this driver building also, the problem is i have to learn about everything else needed about flashlights at the same time :slight_smile: :weary:

Now i am probably making this more complicated than i really have to :-), but i started from 0 flashlights before October last year so this whole hobby is a lot to learn and comprehend to do all the fun mods you guys are doing.

Y5V sucks. IIRC it’s not temp stable, tolerances are wide, turns terrible over time, etc.

I looked at PSMN1R5-25YL very briefly just now. It looks like it might be a great choice, but I did not look closely. I did not look at the other FET.

EDIT: If you can deal with 0603 size then just buy those, they should fit OK on the 0805 pads…

What do you think of the PSMN1R5-25YL and SIR850DP-T1-GE3. Here i make a quick comparison, i included the PSMN3R0 / PSMN6R0 from previous page to compare it.

PSMN3R0 / PSMN6R0 / PSMN1R5-25YL / SIR850DP-T1-GE3

Drain to Source Voltage (Vdss) ———————- 30V / 30V /25v / 25v
Current - Continuous Drain (Id) @ 25°C ——— 100A (Tc) / 71A (Tc) / 100A / 30A

Rds On (Max) @ Id, Vgs ——————————— 3.1 mOhm @ 25A / 6.5 mOhm @ 20A / 1.5 mOhm @ 15A / 7 mOhm @ 20A

Vgs(th) (Max) @ Id ——————————————2.2V @ 1mA / 1.95V @ 1mA / 2.15V @ 1mA / 3V @ 250µA

Gate Charge (Qg) @ Vgs ———————————46.4nC @ 10V / 19nC @ 10V / 76nc 10v / 30nC 10V

Input Capacitance (Ciss) @ Vds———————- 2939pF @ 15V / 1088pF @ 15V / 4830pf 12v / 1120pF 15V
Power - Max —————————————————–91W / 58W / 109W / 41.7W

I can see that the PSMN1R5-25YL has a higher Gate Charge and Input Capacitance, is that bad? The SIR850DP-T1-GE3 has lower Gate Charge and Input Capacitance but higher Rds On (Max) @ Id and Vgs(th) (Max) @ Id.

I suspect that SiR850DP will not give the best performance for single-cell applications.

I’ve looked again at PSMN1R5-25YL. It still looks strong. The turn-on/off/etc delay is high, much higher than PSMN3R0-30YLD. This will probably affect the structure of your modes (I think that they may compress upwards? PWM frequency may need to be turned down? I dunno.)

I see no show-stoppers, I’d go with PSMN1R5-25YL if those were my choices.

Hmm, I did not notice the higher input capacitance. That’s probably related to the slow turn-on time. That could be a problem, but I don’t know. It might be OK.