I am using a MOSFET to power a solenoid. I was told the biggest reason for a MOSFET to fail in this case is the voltage spike when the solenoid is turned off. Below is a link of the MOSFET I am using. I don't know what to look for to tell if is has the diode circuitry to protect it from the voltage spikes.

`http://www.vishay.com/docs/73493/73493.pdf

 

Typically, the flyback protection diode is added across the relay coil. There is an intrinsic diode that is often found internally across the drain and source of a MOSFET but it is the external diode that is most often used to greatest effect.

hgmjr

 

Look at the single pulse avalanche energy rating; it's 281 mJ.

To start, you might measure the inductance of your solenoid and calculate how much energy you must dissipate when you turn it off.

If I is the operating current, and L is the inductance, then you must dissipate something like L*I^2/2 joules.

This rating applies when the FET is allowed to cool down between pulses. In other words, when you only turn off the solenoid every few seconds. If you turn it on and off many times per second, then the single pulse rating doesn't apply.