I want to bench test the MOSFET I chose for a PWM fan control. The system is going to be 12VDC and the fan will be pulling 25amps. Any ideas on how to bench test the MOSFET short of running the fan for hours?
The MOSFET should be fine as long as the die temp does not exceed the manufacturers rating. A crude but effective test is the finger test. If when touched with a wet finger the MOSFET does not sizzle, the case temp is below 100 deg C and the die temp is probably below the spec limit of 150 to 175 deg C. By not exceeding the manufacturer's maximum ratings for even and instant your MOSFET will enjoy a long and happy life.