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problem on Mosfet P-ch getting burned

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siongboon

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Hi,

I am aware that in order not to burn a n-ch while driving inductive load, a flyback diode is being used.

I am current using a half bridge to drive a BLDC motor.
The half bridge mosfet chip kept burning out. The n-ch was ok. It was always the p-ch that kept burning.
The p-ch becomes a permanent short circuit.
Flyback diode had been placed across the p-ch channel to protect the n-ch mosfet.

Am I doing it correctly? How do I protect the p-ch mosfet?

What are the possible cause that can result in p-ch Mosfet being burned?

Thank you for any advise.
 

Can you post your circuit for driving the mosfets? Not sure, but aside from the flyback diode, you may need something to pull the mosfet inputs to a known voltage level at startup. More info:

https://forum.allaboutcircuits.com/...etween-the-gate-and-source-of-an-n-fet.93315/
https://tahmidmc.blogspot.com/2012/10/magic-of-knowledge.html

The links I posted mention n mosfets in particular, but for pmos you might also need to add a resistor from gate to source. I hope somebody else can confirm this. Posting your circuit here will also help others help you :)
 

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