I'm trying to use a P channel MOSFET (FQP27P06) to multiplex 4 large common anode seven segment displays. I'm using a TPIC656 to sink the segments for each digit.
I'd like to use the MOSFET to multiplex and control brightness of the four digits by giving the common anode 18v.
Here is a simple schematic for driving the MOSFET. My concern is when the MOSFET is 'open' I'm seeing the 18v on the pin which would be hooked up to the micro controller.
Is the NPN transistor even necessary?
The second schematic has an extra resistor forming a voltage divider to limit the voltage going to the gate of the MOSFET. I don't think it is necessary with this MOSFET.
I have put the circuit together on a breadboard but I am hesitant to hook it up to the Arduino.
Any help is greatly appreciated.