Re: PMOS in parallel with NMOS

On May 7, 3:24 pm, rickman <gnu...@xxxxxxxxx> wrote:

I put 5 V on the base and 0 V on the emitter for the NPN.
I put 0 V on the base and 5 V on the emitter for the PNP.

I have no idea what you are talking about.  Does your circuit only
consist of the transistors and a power supply???  What you have just
described will blow the transistors.  The B-E junction will only
support about 0.7 volts.  Trying to put 5 volts on this junction will
burn up the transistor.


Of course normally one puts a resistor on the base of a bi-polar
transistor in order to limit the base current, but because the
transistor is being used to power a multiplexed LED with a one
sixteenth duty cycle, I tried taking out the resistor and it worked.
If I increase the duty cycle though, the microcontroller dies. Perhaps
it's the output capacitance of the microcontroller pin that prevents
the current from rising too high before the display multiplexer moves
on to the next LED.. ?
.

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