Ishaan Dalal wrote:

> > limited current.  Is it a good idea to put some sort of electrical
> > "fusing" between a regulated 5 volt power supply and the PIC input
> > pin(s)?  (There is a 3 Amp circuit breaker in the upstream 12-16 volt
> > power supply that I regulated down to 5 volts.)  Would it serve to
> > protect the PIC, associated components, and possibly safety?
>
> As someone said, the PIC is quite hardy, though two common situations where
> you could have it really draw too much current would be overloading the port
> outputs, or inserting the PIC upside down. For the latter situation, a
> "fool's diode" (as Wouter affectionately calls it) would be much simpler
> (i.e., reverse-biased).
>
> I don't think you'd find standard fuses at such low ratings (5V/500 mA, for
> instance). You may want to look in the National 7805 datasheets...I believe
> they have schematics for a current-limited regulator.
>

    If i remember correctly L7805 limits the current to x mA. Can't remember the
figure. If it draws to much current that the L7805 shuts down safely. L7805 is a
voltage regulator.

>
> IMHO, once you are comfortable with PICs, a fool's diode should be all the
> protection you need -- PICs are hardly little things, mine usually even
> survive reverse-insertion so long as I switch it off <2-3 seconds after
> power-up.
>
> Cheers,
> Ishaan
>
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