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CSD19538Q3A: PSE Mosfet Protection

Part Number: CSD19538Q3A
Other Parts Discussed in Thread: TIDA-00290, PMP20588, TIDA-01411

Dear All,

there a numerus different design from TI on how to protect PSE mosfet, which one is the most recommended one?

1) No protection eg:  PMP20588, TPS23861EVM-613 (TIDA-00290), SLVUB84B

2) Protection with Schottky diode eg. : slva233a (STPS1H100),  TIDA-01411 (10MQ100NTRPBF)

3) Protection with TVS diode eg. : TIDA-01411 (CD143A-SR70)

4) Protection with standard diode eg. : slva233a (STTH102)

How to choose the diode for protection?

Best Regards,

David.

  • Hello David,

    Thanks for the inquiry. Protection for the FET is dependent on the application and requirements. Please keep in mind, that you must avoid overvoltage stress from drain-to-source (BVDSS or avalanche breakdown) and gate-to-source (abs max VGS). TI rates our FETs for single pulse avalanche although this condition should be avoided. We do not rate our devices for repetitive avalanche. I am going to pass this onto our PoE apps team to get their input as well.

    Best Regards,

    John Wallace

    TI FET Applications

  • David,

    Please review this app note for surge protection. Thanks.

    Best regards,

    Penny

  • Dear Penny,

    we revived the document multiple times, there are no written guidelines in the document or am i missing something?

    There is only a Schottky diode in the schematic TIDA-01411 (10MQ100NTRPBF), and i saw this before asking the question, what is the logic to choose the protection for PSE mosfet?

    Best Regards,

    David.

  • David,

    Please refer to TIDA-01411 and there's a section in design guide on how to choose the protection components.  We need multiple protection components to protect the PSE port during surge. Thanks. 

    Best regards,

    Penny