At 07:19 PM 9/25/96 +-9-30, you wrote:
>Hi everybody!
>
>At the moment I am testing a fast tracked prototype circuit that uses a
P16C65-20

I had the same problem a few months ago with a 16C73.  After talking with
Microchip tech support they admitted that the problem exists in some of the
'CXX familly devices.  The only cure is a hard power off (Bring VCC down to
0V) and power on.   It seems the problem has been traced to a highside
driver that  powers the SCI function block latching in the off mode when VCC
falls below 1.6V but not to 0V.  The soloution in my case was to wait it out
for the 'A' version part or the 16C63 (I was not using the A/D) which has
the brown out protection circuit which kills power to the device if VCC
falls below 1.6V.


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Richard Katezansky
Tangent Electronics Ltd.
Montreal, Canada
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