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

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.

Will this diode sod-323 work? http://www.ebay.com/itm/20PCS-RoHm-0-5A-20V-Schottky-SOD-323-RB551V-30-/251462325574?pt=LH_DefaultDomain_0&hash=item3a8c529546

At a glance it looks OK to me for 1s to 4s applications. (Only where the voltage divider bypasses the diode, otherwise you’ll have to tune your LVP settings extra. Most of my drivers are that way now, including this one.)

The price looks very good, less than half of what we are paying for ZLLS410.

50pcs not a bad deal might have to pick some up

http://www.ebay.com/itm/50pcs-RoHm-0-5A-20V-Schottky-SOD-323-RB551V-30-/171253520852?pt=LH_DefaultDomain_0&hash=item27df8159d4

Good catch nitro.

It’s cheaper here http://www.ebay.com/itm/RoHm-0-5A-20V-Schottky-SOD-323-RB551V-30-TE17-50pcs-/200990156954?pt=LH_DefaultDomain_0&hash=item2ecbf2689a

This kind of information is great, where can we find all the components for the lowest free shipping price.

I hadn’t even searched ebay for this stuff before djozz build write up and he mentioned it, i just had assumed wrongly that it is mouser/digi-key/farnell and the likes that you find such specific parts.

I built one of these drivers using the original PCB and the parts list below and put it into a triple nichia 219 micro mag. I'm getting 4.7 amps at the tail with an Efest IMR 14500. The light maintains high mode for 5-20 seconds on a freshly charged cell then blinks three times and goes to a light level somewhere between medium and high. Anybody got an idea what's going on and how to fix it?

R1 = 22k

R2 = 4.7k

C1 = 10 uF cap

D1 = SOD323 schottky diode

MCU = ATTINY13A flashed with n-lite by RMM off a QLITE, moon activated

FET = PSMN3R0-30YLDX

Zener and OTC are unpopulated.

Brian

That’s your low voltage stepdown of course.

HKJ - Efest IMR14500 V2 700mAh (Red)

If after monitoring your voltage during the process you find that stepdown is happening at too high a voltage you may increase decrease the resistance of R1.

EDIT: oops, corrected w/ strikethrough text.

What do you suggest I change R1 to, a starting range would help.

Thanks,

B

I suggest you measure what voltage your driver is stepping down at.

You could also switch to a firmware you can modify, so you can set the voltage thresholds yourself.

In case it helps, I have a firmware which will blink out the raw ADC value for voltage. It doesn’t currently do this under load, but that would be easy to change. The point is, you just have to turn the light on, measure the cell voltage with a DMM, write down the value it blinks out, and you’ll have the exact value you need to transplant into STAR or some other firmware. (or at least a few values along a curve, from which you can estimate the actual values needed)

http://bazaar.launchpad.net/~toykeeper/flashlight-firmware/trunk/files/head:/ToyKeeper/battcheck/

3.47v

Is your firmware set up for that 223 at R1 or is it still thinking there’s a 1912 there? That might well be why.

That’s not why. In that case the stepdown would happen at too low a voltage, not too high. EDIT: I was wrong about that. Sorry DBCstm! :frowning:

That said, nlite is a hex from DrJones. It’s precompiled for the reverse polarity protection diode to be in series with the 19.1k/4.7k divider. The 22k/4.7k combo is specifically intended to mitigate the effect of removing the diode from in front of the voltage divider. That’s what this driver does.

Reducing the value of R1 is still the way to go, but if kyfishguy’s numbers are accurate it appears that DrJones setup the stepdown to happen at a much higher voltage than STAR for example.

That is the voltage under load?

(Because if so, this really doesn’t add up to me. DrJones’s standard nlite firmware should be looking for something like approximately 0.55v to start stepping down. The 22k / 4.7k combo should not give such a low voltage until around 3.1v at the battery.)

Yes,

That is the voltage at the battery under load. I'm thinking I'll just start over with new components and a different MCU and see what happens.

I made a mistake in my post above. Now edited w/ strike through and some follow up text.

If you are unable to flash the MCU you should just drop R1 until you get the cutoff you want. I’d try 19.1k based on your measurements so far. If your measurements are not accurate then my suggestion will also not be accurate.

As these guys have noted, you have another problem if you have the R1: 22K and R2: 4.7K resistors in there and it is stepping down at only 3.47v. For a sanity check, it is good to measure what the MCU pin is seeing, as that will rule out all variables except for the MCU itself. As wight noted, it shouldn't start stepping down until around 0.55v on pin 7.

The 22K R1 instead of the 19.1K was to compensate for the different driver layout so that the standard firmware ADC values could still be used.