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TPS54062: Work at VIN=40V, NOT work at VIN=55V

JaeKyung Shin
Prodigy 230 points
Part Number: TPS54062

hello.


I designed a board with a power input of 40V to 60V and an output of 6V using the TPS54062 with reference to the circuit diagram above.

When 40V is applied to this board, 6V output comes out properly.


However, when 55V is applied to this board, sparks occur and no output is produced.
After removing the input power, the status of the board is that the EN, BOOT, and PH pins are shorted to GND.
In this state, even if 40V is applied, no output is produced.

I replaced it with a new part and attached a zener diode to the EN pin as recommended in the datasheet, but it still sparks and doesn't work.

Is there something I am missing?

  • +1
    TI__Guru* 78060 points

    Hello JK,

    Thank you for using our products.  Did you use long cables to connect your board to the power source? If it introduces remarkable inductances, it can cause resonance when you suddenly apply the input voltage, and the IC VIN pin can see higher voltage exceeding its 62V abs max rating.

    To investigate this issue, could you monitor VIN pin to GND pin voltage on a scope when you apply 40V, which should be a safe voltage according to your description, and share the waveform with me?  By the way, the schematic that is shown seems coming from the Webench tool, and I cannot see any problem in it.  Do you have your own schematic when you design your PCB? Can you share your own  schematic for an review?

    Thanks,

    Youhao

  • 0 in reply to Youhao Xi
    Prodigy 230 points

    Hi Xi.

    Thank you for replying.

    As you said, the input power cable is very long.
    I added a 60V ESD Diode to prevent transient high voltages on my board.
    There are no problems like before.

    Sincery

  • 0 in reply to JaeKyung Shin
    TI__Guru* 78060 points

    Hi JK,

    Glad to hear that the issue is resolved.  Good luck in you project, and feel free to contact us if we can be of further assistance.

    Thanks,

    Youhao