Anyone worked with either of these drivers from Lightmalls?

Aack! I interpreted what you said as just needing pins 3 and 4:

NP, I’ll try to do all pins, but probably not tonight…

Sorry, poor choice of words on my part. I look forward to your results when you get a chance.

Thanks for those dimensions, ohaya.

Resistors arrived from Digikey today:

You have to love Digikey (seriously)…. does that packaging look like a bit of overkill or what - I included the pen in the pic for scale :)!!?

I haven’t been able to get all the voltages on the 6-pin chip yet (couldn’t get to the one side w/o possibility of shorting something), but here are voltages to the (emitter side) ground ring with driver in medium mode that I have so far:

Pin 3: 4.18V
Pin 4: 0.115V
Pin 5: 3.12V
Pin 6: 0V

FYI, the resistors arrived, so I put 2 x 0.1 ohm resistors (R100) in parallel, and the current to the emitter goes to 4 amps at about 5V and above. I have one of those laser thermometers, and checked various points on the driver, and temperature seemed about 80F.

I tried a short test where I cranked the Vbat/Vin up, but I thought that I saw some smoke, so I shut it down.

The driver still worked after that, and I visually inspected with a 30x magnifying glass and I didn’t see any obvious (to me at least) signs of damage. Also, there wasn’t any “burnt smell” that I noticed, so maybe I was just imagining it.

We know the SS34 Diode is only rated to 3A max continuous, so that is one part I would be watching for the magic smoke to get out. Maybe look for some bigger diodes in the parts drawer.

I kind of suspected the SS34, since that’s the part that got kind of lifted off of the board when I pulled the R200 earlier, but it (the SS34) still looks ok (no blistering/bulging, no burnt odor), but it’s possibly on the underside, that I can’t see.

Would these work, both electrically and size-wise:

http://www.ebay.com/itm/20x-B54-SMC-DO-214AB-1N5825-SMD-5-0A-Schottky-Rectifier-Diodes-NEW-/251095507434?pt=LH_DefaultDomain_0&hash=item3a767561ea

??

And if they do work, does that mean I’d be able to run 5 amps?

EDIT: According to this, the SS34 is DO-214A package also, correct?

EDIT 2: What about this one from Digikey (the qty 1 one, not the qty 3000 one)?

http://www.digikey.com/product-search/en?KeyWords=SK510L-TP

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 :)…