On Mon, 16 Jul 2001 13:45:05 +0200, you wrote:

>On Wednesday, July 11, 2001 6:40 PM, Wouter [mailto:wf@XS4ALL.NL] wrote
>>
>> The 'normal' PIC pins have a protection diode to Vcc, so you
>> can not use 'm
>> to switch a voltage greater than Vcc. (not even using a
>> simulated open-drain
>> by switching the direction). So with such a pin it would not
>> be possible for
>> me to create my programmer (which switches the Vpp using a
>> PIC pin - RA4 of
>> course). So uChip included - for my joy - one pin without the upper
>> protection diode, that can withstand a voltage up to 14V. I
>> guess the upper
>> driver FET would not like being reverse-biased, so they had
>> to make it open
>> drain. In't it great that I had such an impact even before I
>> knew what a PIC was?
>>
>If i remember correctly, Microchip has revised the specification in the
>errata.
>RA4 can withstand up to 10V.
>Correct me if i'm wrong.
RA4 does not have a diode to Vdd, but I've seen at least one mention
somewhere of this being used for factory test, so using it above Vdd
could be risky. This may  only apply to older devices - I think it was
mentioned in a very old C5x data sheet.

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