Thanks for the pointers Russell, I'll add decaps when I add the PIC and will make sure that I use a PWM pin for DISCH_CTRL. Thanks, Chetan Bhargava http://microz.blogspot.com On Mon, Aug 27, 2012 at 8:24 PM, RussellMc wrote: >> I have modified the schematic as recommended by you. Hopefully it should >> work. >> >> http://i.imgur.com/vxChU.png > > Chetan - that looks good. > It will work :-). > Supply decoupling cap on U1 at IC "a good idea". > MOSFET has nicel low Vgsth. > Datasheet here: http://www.fairchildsemi.com/ds/MT/MTD3055VL.pdf > Rdson is low enough gthat if driven g=3Dhard on dissipation should be > minimal at say 1A. > > You could PWM it on/off > You could apply PWM via a resistor with cap on gate to ground to form > a variable DC voltage. This allows variable current drain with current > feedback to pocessor - noting that FET dissipation will rise when it > is used as a resistive load in this way. > > > Russell --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .