I need a high side switch. I thought about using a p-channel MOSFET. The source will be connected to around 50V-60V. How can I drive this MOSFET? I can't find a driver which can switch between 60V and 45V in order to put the MOSFET on and off. They all switch between ground and Vcc, which is generally below 25V. How is switching a high-side p-MOSFET at 60V done? My control signal is at 3.3V.
EDIT:
I want to avoid a second power supply. The microcontroller used for the signal generates a signal for a low side n-MOSFET as well.
EDIT 2: The goal is to drive a chopper for a motor, so the switching frequency I was thinking about is around a few kHz.
Best Answer
What you're talking about is generally called a level shifter. Assuming you don't want high-frequency switching, you can use a circuit like
simulate this circuit – Schematic created using CircuitLab
A few tips. The NPN must be rated for more than 50 volts. You can play with R3 and R4, but the total resistance should give a current at 50 volts of about 10 times the NPN base current or less. Larger values will dissipate less power in the resistors, but will also interact with the FET gate capacitance to slow switching and increase the power dissipated by the FET. Adjusting the ratio of R3 and R4 controls the gate drive voltage, so don't get carried away. A 1 to 3 ratio at 50 volts gives 12.5 volts and 15 volts at 60, which should be just fine.