> Is 1uF really that big ?

Yes, I definitely wouldn't do this.  When power is shut off and the power
supply drops, the cap will discharge thru the PIC.  The cap current is I = C
* dV/dt = 1uF * 5V / Td,
where Td is the power supply discharge time in seconds.  If your supply
discharges in 5mS then the average cap current will be 1mA.  If the PIC
doesn't allow that current, then you enter unspecified territory with MCLR
at 5V and everything else at 0.

> I recall others on the list who routinely
> use 10uF or more with no apparent problem.

Now you get 1mA average at 50mS discharge time.


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

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