Building a mod around the OKL2-T/20 chip

[infamousace]

Hello, I just got the OKL2-T/20 DC-DC converter chip in and I want to start building.

I saw what MAMU did with her mod chip:
http://www.e-cigarette-forum.com/fo...kering-okl2-t20-20a-110w-dc-dc-converter.html

I don't fully understand some of the components, though. I kind of just want to wire it up according to the very crudely drawn schematic in the uploaded file.

MAMU's forum states the +sens and -sens aren't entirely necessary, I don't see what the use of the transistors are or the 20k resistor connecting on/off and Vin.

Will this basic format work without frying the chip? I plan on adding the fuses and a volt meter to it. I might even add the low voltage circuitry detailed later in her thread.

Thanks.

 

[Jackson]

Well I made a few notes to your pic.

I guess where I now have the red X was where you wanted a fire switch? If so you would eliminate the line to on/off, blue X. You would need a decent high amp switch in this config. This is the 'N' (neg logic) version of the converter.

From the datasheet.

Negative—Units are enabled when the ON/Off is open or brought to within a low voltage

By keeping the line and adding a 20k pull-up resistor the converter will now be off, as it is now pulled HIGH (to V+) which will keep it OFF. On the left you should be able to use any type of switch and simply pull it LOW. The 10k resistor is just a guess, many values will probably work. You could probably just use a cheap, little 20k trimmer (pot) and dial it in till it fires. With the trimmer you may also be able to dial in a voltage cutoff, get your cells down to ~6V and tweak the trimmer till it no longer fires. It may work as many converters mention this (input UVLO function) and have formulas to determine the resistance needed.

I think that should work.