P-Channel MOSFET woes - anyone know how to drive one of these things with Arduino?
So far everything seems to work except I clearly can’t figure this P-channel MOSFET out (IRF6540)! No matter what I try I always get a high voltage at the drain pin (full-on condition) regardless of what I do to the gate pin. I uploaded a portion of my schematic as a test circuit I think should work from my limited understanding and online tutorials: http://www.curtismasonjohnson.com/sandbox/ProblemCircuit.JPG
- The NPN driver in the drawing (2N3904) by itself works when tested with a voltmeter and toggling the input
- If I replace the p-channel mosfet with a PNP transistor it work as expected. Shouldn’t this mosfet work pretty much the same? My puny TIP127 PNP can't handle the current if I were to hook up the load.
- I’ve tried several IRF6540 components
- I’ve tried connecting the MOSFET’s ground pin via a current limiting resistor directly to ground. Also via the resistor to 13v. No voltage change on the drain pin in either case.
Clearly I’m missing something embarrassing and fundamental. I mentioned I’m a hobbiest, right - my day job is managing global marketing programs for fortune 500s and don't know anyone that knows anything about electronics! After years of electronics & robotics projects I’ve yet to be stumped to the point of needing help til now - amazing how much you can self-teach via google and such. This one has me beat – hope someone can help as I have no idea what to do next! Truely appreciated...