Dan Michaels wrote:
>
> David Venz wrote:
> >Dan,
> >
> >The question would be - what is a "safe" current in each variety of PIC's
> >internal input circuit?  Where did you get your figure of 25mA from?
> >
>
> David,
>
> I just checked the datasheet for the 16C7x, and it actually says +/-20 mA.
> Max input clamp current, under Electrical Characteristics.
>
> If you use a 330 ohm series R in each line, like I do as a general rule,
> then you have ~7v overvolt protection. My personal philosophy is to
> NEVER hang an unprotected pin onto a header for external connections,
> etc. 330 ohm is a nice choice, IMO.
>
> However, during qualification testing - specifically intended to help
> determine what stress levels the internal diodes could handle - I have
> purposely applied up to 80 mA via series R, and not had the internal
> diodes pop. So, I assume there is a fair margin of safety on the spec.


Dan, what was the diode drop at 20mA and (!!) 80mA?
ie, how much above Vdd did the pin get with 20mA into
it?
-Roman

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