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TPS43060: High/Low-side gate rise/fall time too long issue

xiangnan qu
Prodigy 20 points
Part Number: TPS43060


Hi Sir,

I am using tps43060 drive the mosfet BSC098N10NS5 and find that the low side gate is very hot and the gate rise time is very long(I think it should shorter).

Desgin input: 19V input, 54V1A output


MOSFET Qg total: 25nC max

Frequency: 450kHz


The question is the gate rise time is about 300ns and it is longer than I expected which should be about 100ns?

I think there is some problem with the layout, but I am not sure what cause the rise time unexpected?

Best regards,

Xiangnan

  • 0
    Prodigy 20 points

    OK, I am not hoping someone can help to debug my problem. I just want somebody can help to explain what is the rise time should be.

    Best regards,

    Xiangnan

  • 0 in reply to xiangnan qu
    TI__Mastermind 31870 points

    Hi Xiangnan,

    Thanks for using the e2e forum.

    I agree that is thermal issue might be related to the layout.
    Looking at the power stage, it seems like the inductor is very far away from the two switching FETs.
    This can create strong noise and parasitics.

    The power stage should be designed as compact as possible.
    The TPS43060 datasheet has a section designated on layout guidelines. Please follow these steps for an improved layout design.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    Prodigy 20 points

    Hi Niklas,

    Thank you so much for your sugestion.

    I am improving the layout following the guideliens.

    I just wonder if there is a problem with the rise time of the Gate voltage, I am worried that too much rise time increases the switching loss and causes the temperature of the MOS to be too high.

    I can not find a way to adjust the rise time, the Qg of the MOSFET is given, can you help to check the if rise time is correctly be set up?(

    The gate rise 330ns now.)

    Best regards,

    Xiangnan

  • 0 in reply to xiangnan qu
    TI__Mastermind 31870 points

    Hi Xiangnan,

    Yes, I agree that a very slow rise time will increase switching losses and heat up the FET.
    This issue might be related to the FET itself, so it would be a possibility to try another FET and check if the behavior improves.
    Another idea would be running with lower switching frequency.

    Best regards,
    Niklas