> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of John Nall
> Sent: Sunday, May 04, 2003 9:10 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE]: Transistor switch - PNP vs. NPN
>
>
> This is probably an extremely basic question for the engineers, but not
> being one I don't know the answer.  Have googled around trying to
> figure it
> out, and can't.  So will ask.
>
> When using a transistor for a simple switch (in this case, because the
> amount of current will exceed the capability of the I/O pin on a PIC) is
> there a rule of thumb for when to use a PNP and when to use an NPN?  Since
> the I/O pin, controlling the base, obviously can either be set
> high or low,
> it seems that either would work equally well.   But perhaps there are some
> "gotcha's" that I don't know about?

Although I prefer to use power FETs, I'd suggest PNPs as an inverter.
However, NPNs seem to be more common.

>
> Thanks,
> John
>
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