Hi

I am trying to find the best way to make a high side switch to control an
auxillary power source for my pic in an automotive application. When ignition
switch voltage is present (13.8V or so) I want the pic to control a switch
that will direct 12V battery power to the  5V regulator for perifferals. When
ignition switch is off,  high side switch will cutoff bat supply to 5V
regulator for perifferals.

I would like a logic level signal from pic to control 12V source to regulator.

My plan was to use a pnp mosfet. It said it was a logic level hexfet, but it
did not work. I tried an npn logic level mosfet and it didn't work either. It
appeared the gate logic was dependent on the batter voltage. I got a  pnp
transistor to work when gate voltage was above or below the batt voltage, but
it was the inverse of what I was looking for. I know I am missing something
simple.

It seems so simple I have done it in the past using 5v relays, but I thought
there must be a simplier SS solution .

Could you provide some suggestions on how I can make a logic level high side
switch cheap?

Thanks

Jon