> > This is why I suggested using a high side current sense chip like the L=
inear
> > Technology LTC6101, LTC6102, LT6106 or Microchip PAC1921.=20
> > These would work with a PCB trace at about that resistance and feeding
> > that into an ADC would allow configurable current monitoring.
> This sounds like a good idea.  Some nice chips here.. Just wondering if I=
 put
> the voltage out of these chips  into an ADC on my PIC if that would be fa=
st
> enough to catch a short before my FET fries. I'll have to take a closer l=
ook at
> the time it would take to read the ADC and take action. Because I am usin=
g
> PWM ( around 15 KHz ) I guess I would need to
> synchronize my ADC reading with the on state.   I have read that FETs
> can burn out fairly quickly ie. 10 uSec so the conversion and taking acti=
on to
> turn off the FET would have to occur fast.
> Jim

I assumed that as you mentioned PWM control of the FETs that there would be=
 a micro involved to drive the PWM, and that the current sense chip would f=
eed the micro. The micro would then handle a serial comms link to a PC for =
a source of commands re LED brightness etc., and to supply the PC with erro=
r/diagnostic information.

There are PIC chips designed for motor control that have a current sense fe=
edback input to allow the drive to the motor to be turned off but I don't t=
hink these would act correctly for driving LEDs.



--=20
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