Thanks to all who have responded to my PIC drives MOSFET question.  Some
of the best info was regarding the voltage drive levels to the MOSFET
gate.  It appears that 5V may not be enough gate drive.  It also appears
that I may need enough current drive to insure that the gate turns ON and
OFF (source and sink) very quickly so that I spend very little time in the
high resistance region.  That could also account for excessive MOSFET heating.

        So here is the prize question... the winner will have my eternal
gratitude (I'll pull a thorn out of your foot someday):

        Does anyone know of a single-chip solution to interface the PIC
output (5V) to the MOSFET gate (around 12V) with plenty of source and
sink capability.  I hear the MOSFET gate capacitance can be as high as
1600pf (I do not have a data sheet on the IRF520) so current drive should be:

        I = C*(deltaV/deltaT) = 1600pf * (12V/100nsec) = 192 mA

        A bipolar transistor voltage translation could work.  I need 8 of
these for 8 channels of MOSFET drive.  So single-chip solution means all
8 channels.

Thanks all,

Martin Kirk
Arizona State University
mlk@asu.edu
(602) 582-5718