At 06:18 PM 2/27/2004 +0100, you wrote:
> > Ahah!
> >
> > The MOSFET gate has to get within 200mV or so of the 5V rail
> > to make sure it is turned off.
>
>That's what the internal pup in the MIC should take care of.
>Note that the PortB pin is *tristated* in the "off" state
>using the TRIS reg, not driven activily high (to 3.3V).

No, it will only go up to about 3.8V because of the internal
diode to the 3.3V Vdd on all port pins but RA4 (and /MCLR, but that's no
use).

I suggest paralleling the internal pullup because it will turn
the MOSFET off too slowly and cause a lot of
unnecessary heating, unless the power drain is of more importance.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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