> I am building a motorcycle headlight modulator using a PIC to monitor
> ambient light and a few other things.  Anyway, the PIC has to modulate the
> headlight ( ~ 4Amps) at a arount 240Hz or so.
>
> There are a few legal stipulations.  They say that you cannot switch the
> ground, you must switch the +12V to the headlight.  I want to use a low
Rds
> HEXFET or simular transistor, but I think I would need a P-Channel device.
>
> Is a P-Channel Mosfet difficult to drive from a TTL logic level, such as a
> PIC.

You wont be able to drive it with 0-5V when it is sitting at 12V.  However,
it should be rather easy to generate the 0 to 12V gate drive.  Most FETs
will fully switch with 12V gate drive.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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