Using amc7135 driver for m140?

[bdgreenb]

Howdy y'all!
Ordered this driver on a whim to see if i could use it to drive an m140.
I know it won't most likely put out 1.5A, but i am interested in how much less.

17mm 1 5A CC 4 2V 5 Mode CREE XP G R3 R4 R5 LED Flashlight Driver | eBay

i plan on using 2X Tenergy 3V LiFePo4 750mA, and i plan to discharge them a bit (hopefully below a combined 6V)in a more powerful laser before use just in case. And the driver will be nice an HS'd.

Am i missing something here? or will this work?

Best Regards
-Bryan

 

[LarryDFW]

Bryan;

You will need a Zener Diode + resistor to limit the voltage going to the 7135 to under 6VDC.

Then you won't have to worry about the cell voltage.

LarryDFW

 

[bdgreenb]

hmmm think i kinda got it, but i could be completely wrong,
went off an equation for 12V->5V

so to drop voltage for 2x Lions(8.4) -> 5.6V it would require a ~7.8 Ohm resistor?

2W/5.6V= 357mA , (8.4V-5.6V)/357mA= 7.84 Ohm

 

[dubious speculation]

The atmel attiny13a MCU on that driver has a voltage limit of 5.5v.

As LarryDFW said the zener diode and the resistor will limit the voltage going to the MCU and amc chips.

Although I wouldn't have bought that driver for 9 bucks. Here's the same one from fasttech for $2.5

I know it won't most likely put out 1.5A, but i am interested in how much less.

If the input voltage is above the operating voltage it will give 1.4A on high. Each amc chip provides 350ma and there are four of them.

 

[bdgreenb]

thanks for your answers

meh you know how late night flee bay goes ><
also whats the worst case scenario if the input voltage is too high?
Something other than A LOT of heat frying/ damaging driver components?

 

[grainde]

The will be a sizzling sound then the IC will die. Done that and been there. Replacing (reflowing) the IC didnt help either.

Ive done several zener resistor mods for MT-G2 mods and occasionally there was a problem...:beer: