On Sun, 5 Feb 1995 Shane Trent said: >>Can anyone recommend a readily available power MOSFET with low on >>resistance (<0.03 ohm) when directly driven from a PIC output (5 volt >>supply). I ordered what looked like a promising device from Digi-key, >>only to find out that it was "vapor-ware". Current capacity required >>is modest, but must have low Ron. Thanks >> >>jk > >If you can get +12V somewhere you can switch MOSFETS with the PIC. Just >connect the PIC output pin to the MOSFET gate and pull the gate to 12V with a >10k or so resistor, larger means slower response when turning on. You may want >to put a small, 500 ohms or so, between the PIC and MOSFET gate. This is to >limit the short current spikes that may occur when discharging the gate >capacitance of the MOSFET. Now you can turn the MOSFET on my making the PIC >pin an INPUT, this should put the pin into a high impedance state, letting the >MOSFET gate be pulled high by the 10k resistor. To turn the MOSFET off, just >make the pin an output and drive it low, pulling the MOSFET gate to ground. > >Hope this help, >-shane You might have a problem with this. Every i/o pin on a pic has protection diodes to both VSS and VDD. This limits the pin voltage to about 5.6 volts (if vdd=5v). I suppose you could get around this with yet another diode, but now it's getting a bit more complicated then the original request. later ....... carl Henry Carl Ott N2RVQ carl@pipeline.com ------------------------------------------------ No wife, no horse, no spell checker. ------------------------------------------------