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UCC25661: Protection Circuit for HO Pin of UCC256613 During MOSFET Failure

Conor
Guru 12115 points
Part Number: UCC25661

Tool/software:

Hi,

We are currently experiencing a failure mode in our LLC power supply design using UCC256613, where the controller IC itself is damaged due to back-feed when a MOSFET fails.
In particular, we have confirmed that when the high-side MOSFET fails, the HO pin of the IC becomes non-functional.

To mitigate this, we are considering adding a Zener diode between HO and HS.

We would greatly appreciate your guidance on the following points:

  1. Are there any recommended protection circuit configurations for the HO–HS pins of UCC256613? If using a Zener diode, what voltage/power rating would you recommend?

  2. Are there any other effective protection measures (e.g., snubber circuits, TVS diodes, etc.) to prevent damage to the IC in the event of MOSFET failure?

We appreciate your support and look forward to your advice.

Best regards,

Conor

  • 0
    TI__Intellectual 1080 points

    Hi Conor,

    Understood your point. I will prefer considering a TVS diode rather than zener diode for protection, as zener may consume power for all the time of operation. 

    My recommendation will be , before using TVS diode or any protection scheme, if possible, please check if the failure of MOSFET can be prevented or not.  

    Regards,

    Sougata