Anyone worked with either of these drivers from Lightmalls?

I was just thinking of something (it happens once in awhile), and have a stupid question: How is it that the MCU on the 16mm driver doesn’t just get fried when I, say, put 9V input?

I’m not sure MCU is the proper term for that thing. Regardless of the terminology, I think the answer is that a zener diode is used to power it. Google has simple diagrams for a zener and resistor together, that is the arrangement I’m referring to.

Ahh. Ok, so it’s similar to what comfy does with the 7135-based drivers, i.e., use a zener to drop the Vbat/Vin to a voltage that the MCU/controller can work at.

Any idea if that diode I linked at Digikey could be swapped into the driver and let the driver work at 4amps?

FYI, I’ve gone ahead and ordered a couple of the SK510L-TP diodes from Digikey and will try to swap them onto one of the drivers and see if it’ll run at 4 amps (or maybe more, I also order some 0.05 ohm resistors :laughing:.

EDIT: Pretty soon, I’ll have enough parts to build these drivers from scratch like you all do on the Oshpark projects :)!!

We’ll see how it goes. I suspect that the best case scenario is that efficiency is quite low with the tiny FET. :~

This whole thing should be interesting, huh? I have a few places where I can/would really like to use a tiny 4A, 2 x Li-Ion driver awaiting.

Yeah, I know exactly what you mean. I think a fair number of folks here really want a small, powerful buck driver. I’m definitely on the list. After we’ve got that hammered out I suppose the only thing to do is focus on a small, powerful boost driver :wink:

I know that I’m a bit slow on the uptake, but after working with this for a few days, I’m now understanding (seeing the possibilities more clearly) of the buck driver!

I can’t wait to see how the new diode works out and if I don’t kill the drivers!

While waiting for your 5A diode, you could set it for 3 Amp and do some measures to see how well the driver is handling that load: Voltage and Amps in, volts and amps to the LED.
The efficiency will tell you how much power is lost (heat) in the driver and if it is likely to be able to handle more current without smoking it.

I had stacked 2 x R200 and 1 x R100 resistors earlier, on the 1st driver, and from this post:

So, I think I can just go back and get those numbers with that driver, and it’s close enough to the 3 amps you were suggesting?

… if you got the Voltage and Amps on the input (battery/power supply), and the voltage & amps on the output/ LED at the same time, then Watts out/watts in will give efficiency.
I didn’t see all those numbers for the 2.8A test. Power lost in the driver will go somewhere; it will turn to heat.

In other words, LowLumen isn’t worried about exactly what current you are using. It’s a matter of collecting all that data he mentioned. Once you have that at 3A, 2.8A, or whatever, we’ll know power in and power out. The difference will represent losses in the driver (as heat), exactly as LowLumen stated.

Understand that guys :)…

It will give some idea of how likely you are to smoke it by pushing it harder too. Try to be as accurate as possible with the measures. If you are using a clamp meter on the LED current, try looping the wire through the clamp twice & /2 on the reading for better accuracy.

….well, I like efficient drivers too :bigsmile:

Sorry son, didn’t mean to be pedantic. :wink: :bigsmile: :bigsmile:

Hi, Here's the In vs. Out info:

Vin Iin Pin (watts) Vout Iout (x 2)
3 0.63 1.89 2.84 0.8
3.2 1.15 3.68 2.93 1.86
3.4 1.81 6.154 3.02 3.15
3.6 2.25 8.1 3.06 3.99
3.8 2.73 10.374 3.09 4.96
4 3.26 13.04 3.11 6.02
4.2 3.63 15.246 3.12 6.7
4.4 3.88 17.072 3.12 7.18


Vin/Iin were what was displayed by the bench supply.

The table above was done as suggested, with one of the emitter leads looped through the clamp meter twice.

Vout/Iout were measured using the clamp meter (again, looped twice) and a voltmeter attached to the emitter leads.

EDIT: Sorry, I forgot to mention that this was the 1st driver, the one where I stacked R200, R200, and R300 resistors.

EDIT 2: Emitter was an XM-L, on Noctigon, sitting on a (maybe) 1/4" copper plate with thermal paste.

BTW, there have been multiple mentions of the FET. Which component is the FET? Is it the 2 of them that are marked “AOEC”?

EDIT: It looks like the new diodes (plus a bunch more of resistors) will get here today via USPS.

I was thinking about this driver, and my question above, and realized that we, or more precisely, I, have not identified all of the components on this driver yet.

Referencing the pics at Anyone worked with either of these drivers from Lightmalls?

- We know the R200 is apparently the 0.2 ohm sense resistor.

- I think the SS34 is schottky diode.

- What is that “LEDA 1322” chip?

- What are the “A0EC” or “AOEC” chips?

- What is the “151”?

- What is the “W8”?

- What is the “S4”?

Anyone?

I think a closer look at some of what’s already been posted may address this but…

SS34 is the schottky diode (identified in simple [asynchronous] buck diagrams)

LEDA 1322 is a QX9922 buck controller, see my earlier post. Buck circuits all have some sort of control hardware to open and close the switch you see in any simple diagram (MOSFET in real life). The QX9922 is only present to handle the buck section, modes are handled with another chip which controls the QX9922 through a PWM signal.

AOEC/A0EC/whatever is the FET (MOSFET) - there are two but it’s not clear to me that both of them are actually part of the buck circuit. Other drivers also have a weird two-FET arrangment, see my post in comfychair’s New version DRY driver info thread goes here. Post #32.

151 is a resistor, 150-Ohms I suppose unless I’m crazy again (LowLumen will hopefully correct me in that case).

W8 is a zener diode - this is used along with a resistor to give a fairly regulated low voltage (5.1v probably?) for the QX9922 and the modes chip.

S4 is another diode. It’s probably a reverse polarity protection diode (protects the driver).

If you aren’t going to rebuild the damaged driver, please fully strip it of components and attempt to take clear pictures of the traces. Scraping the resist off of the whole thing in order to expose the copper is a valid thing to do.

If you are going to use it then you certainly can’t do that, but if you got really motivated you could check and see whether the wiring is similar to what I describe in post #32 of the new-dry-driver info thread.

wight,

Thanks for collecting and summarizing that info.

My situation is that I am hoping to keep working with the 2 copies of the driver that I have.

I already re-soldered the couple of components that got “blown away” by my super heat gun trip, and that driver is working again, and in fact, I put an R100 stacked on the R200 and I’ve seen 4+ amps at the emitter when I was just messing around with it. That was the one where I thought I saw a puff of smoke, but I haven’t gotten the nerve to try that again yet. I consider that driver (the one with the R100 in parallel with the R200 my main “guinea pig”, and the other one with the R200, R200, and R100 in parallel my “baseline”.

The new schottky diodes just got here this afternoon, so I’m going to try to replace the SS34 on the guinea pig driver with the new diode and see if it works. If it does still work, I’ll see what happens if I up the Vin/Iin.

Different topic: I haven’t ohmed it put yet, but I was assuming that they just put the two AOEC/A0ECs in parallel, i.e., the source and drain tied together, kind of like all the 7135s on a 7135-based driver are in parallel. Would that NOT be the case in this driver?

Anyway, so I’ll do that (ohm out the AOEC/A0EC) to see if they’re tied together, then I’m going to try to swap the SS34 out, and then see what happens after that.

Thanks again for your help. This has been interesting, and I’m really hoping that if I can swap out the right parts, I can get to that “small driver” that you mentioned. I guess that to do that, potentially, I/we need to figure out exactly what the AOEC/A0EC is and if they’re paralleled, and if they are maybe I can stack more AOEC/A0ECs, like they stack 7135s??

Sure thing.

Short answer: No stacking & they are not in parallel. It’s visible from the pictures you took. I can tell how it’s not hooked up, I just can’t really tell how it is hooked up.

EDIT: and I’m looking forward to your results with the new diode.