problem on Mosfet P-ch getting burned

[siongboon]

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.

 

[ernpao]

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