On Thu, 21 Mar 1996, Newfound Electronics wrote:

> I don't know what you mean Dermot. To my understanding we have a low
> impedence source controling Vdd and a high impedence source from Vpp/MCLR.
> The voltage difference is dropped across the resistor. What could I be
> missing? At worst Vpp contributes a little extra current, Right??

Hi Jim,

Yes, It's my logic that's a little fuzzy. I'm thinking in terms of the
circuit I'm currently working on where the programming voltage is derived
from a different source to the PIC Vdd supply line which itself contains a
blocking diode. Your description relates to the PIC deriving Vpp and Vdd
from the programmer, clearly a better arrangement.

I'll bear this, and the potential 16C84 ESD problem, in mind in any future
designs.

Regards,
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