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What is the usual cause of damage regarding MOSFET?

Latest Updated:09/02/2013

Question:

I'm testing a DC motor using a power MOSFET and an H-bridge circuit, but I can't control it and the MOSFET gets damaged. I'm using the following specifications.

  • DC power supply: DC5-16V
  • DC current: 0-25A

If normal rotation, reverse rotation, and stop is repeated continuously, the n-channel MOSFET heats up and becomes damaged. There is a 10 msec interval switching between each control. If only normal and reverse rotation are performed, there is no problem, but if rotation is stopped the n-channel MOSFET is damaged when it is turned on. What could be the cause of the damage?

Answer:

  1. Is heat sink of a sufficient size?
    If the heat sink is small, thermal resistance will be high and channel temperature will rise. If the rated channel temperature is exceeded, this could result in damage.
  2. Are you turning on the p-channel MOSFET and n-channel MOSFET of the H-bridge circuit simultaneously?
    If the connected p-channel and n-channel MOSFETs are turned on simultaneously, penetration current flows into the MOSFETs and could cause damage.
  3. Is any external power being applied to the DC motor (and generating power)?
    If power is being generated the power supply voltage will rise, and may go overvoltage, causing damage.
Suitable Products
Power MOSFETs for General Switching