> > Shorting a pin to ground or vdd and then driving it the other way 
> > violates the absoloute maximum ratings of the pic. However the 
> > impression i get is that in practice you will get away with it 
> > provided its just one or two pins but if its lots of pins 
> you may well 
> > fry stuff.
> 
> Ok, understood.   And in cases like this, it's important to understand
> the mechanism behind the limitations. "Don't do this" is much 
> less useful than "If you do this, it causes that to happen, 
> and that's bad".

But remember that the fact that the manufacturer does not allow some
condition (in this case, a high current) for a particular reason, gives
him full freedom to chance his design, so tomorrow that condition might
cause a different failure mode. So insight might be usefull, but you'd
better not rely on it. This is especially true with Microchip who uses
3d party fabs so they change fabs and process more often than other
manufacturers.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 
 

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