> I going to use the pwm to drive a 2N2222A which is in turn going to
> control a mosfet. I wanted to know if the pwm that is produced is a
> clean square wave or if it is really dirty and has to be cleaned
> before it will let the 2222 switch nicely.
>
> Of course I read the bit about the dirty pwm output in a app note and
> now can't find it again. And if I had a pic running right now I could
> look and not have to ask dumb questions ;-]  Was just curious if
> anyone had actually noticed this or if its another "caution"  to just
> ignore.

Dave,

It is a really clean square wave as far as I have seen, no nasty
glitches or double pulses to cause any problems. I have not heard of
any such cautions. It is a push-pull output like most PIC outputs and
will drive the 2N2222 nicely with an appropriate base drive resistor.

It can also drive a MOSFET directly, perhaps even better than if you
used the 2N2222 in between. That is, if the MOSFET does not have too
much gate capacitance and if 5V gate voltage is OK.

--
Brent Brown, Electronic Design Solutions
16 English Street, Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/txt: 025 334 069
eMail:  brent.brown@clear.net.nz

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