> then into the poor little PIC, where it will switch on the protection
> diode, i.e. voltage on the PIC pin will be clamped to Vdd+0.6V
> 
> A small NPN would be suitable to drive the gate, with the collector
> connected to the existing resistors, the PIC driving a base (via a
> current limiting resistor) and the emitter grounded.

Yes, I spotted that myself a short while ago. That's what I'd do,
although given that the gate R from B+ is large (in the example
link is 5M6 -> a couple of uA) and the PIC pin is an output, the
B+ through this may not have enough clout to do any harm. But
you're quite right, an external transistor would be prudent. The
B+ R might probably be lowered in a revision as there are switch-
modes and an RF modem in the unit, so noise could be an issue

> The figure you are interested in for the MOSFET is the Vgs
> voltage required for the maximum Drain current you expect to see,
> with an acceptable Vds (i.e. voltage drop accross Drain-Source

Thanks

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist