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TPS65983B: External MOSFET burnouts when system did OCP(20V/5A) test

Ray Chang
Intellectual 1345 points
Part Number: TPS65983B
Other Parts Discussed in Thread: TPS65981, CSD16323Q3

Hi, Team

My customer did the OCP test on TPS65983B, 

When system tested the OCP at 6A, we found the external FET will be damaged(Q2) .

We found the PD controller will limit output current around 4~5A when over current be detected; then the external MOSFET be damaged(Q2).

Could you please help to check OCP behavior which is normal or abnormal by below waveform?

  • 0
    TI__Genius 10370 points
    Hi Ray,

    Welcome to E2E! Are you building a Thunderbolt 3 ecosystem?

    The TPS65983/B are only used for Thunderbolt 3 reference designs by Intel. If you're not building a thunderbolt system, then the TPS65983/B is NOT recommended. I would recommend the TPS65981.

    If you are building a thunderbolt 3 ecosystem, then could you answer some questions below:

    1) Could you check the USB cable to see the current rating? Most USB-C cables are rated for 3A, but there are a few that are rated for 5A. If the cable isn't rated for 5A, there could be issues.

    2) What's the part number of the FET that you are using?

    3) Could you explain to me the steps you performed for the this Overcurrent Test procedure?

    I hope this helps :-)
  • 0 in reply to Aramis P. Alvarez
    TI__Intellectual 1345 points
    Are you building a Thunderbolt 3 ecosystem?
    Yes.

    If you are building a thunderbolt 3 ecosystem, then could you answer some questions below:

    1) Could you check the USB cable to see the current rating?
    Most USB-C cables are rated for 3A, but there are a few that are rated for 5A. If the cable isn't rated for 5A, there could be issues.
    do you mean if the cable isn't rated for 5A, the external MOSFET will be burnouts? why?

    2) What's the part number of the FET that you are using?
    FDMS0312AS/NTMFS4C027N, both parts are be burnouts.

    3) Could you explain to me the steps you performed for the this Overcurrent Test procedure?
    The customer used the electronic load to add a step 6A load to test OCP on the VBUS when the 20V PDO be contracted.

    From the waveform, the OCP behavior is normal or not?
  • 0 in reply to Ray Chang
    TI__Genius 10370 points
    Hi Ray,

    Thank you for your responses to my questions. What Intel reference design is the customer following?
  • 0 in reply to Aramis P. Alvarez
    TI__Intellectual 1345 points
    Customer is following Tahini reference design,
    We need you help to check OCP behavior asap,
    base on the waveform, could you please help to check the OCP behavior is normal or not?
  • 0 in reply to Ray Chang
    TI__Genius 10370 points

    Hi Ray,

    The OCP behavior seems normal to me. But I did notice that the customer is NOT using the proper FET's according to the Tahini reference Design. For thunderbolt systems to behave properly, one MUST copy the Intel reference design and not deviate from it.

    The Tahini reference design has CSD16323Q3 FET's.  Please have the customer use these FET's and copy the reference design when building a Thunderbolt system.  I hope this helps If this answers your question, PLEASE select  This resolved my issue.

  • 0 in reply to Aramis P. Alvarez
    TI__Genius 10370 points

    Hi Ray,

    Since we closed this thread, could you PLEASE select  This resolved my issue  

    Thank you so much for your question and choosing TI parts for your design :-)