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TPS54425: Would you please tell me about parastic inductance of TPS54425?

michihiro akashi
Prodigy 120 points
Part Number: TPS54425

Hello,team.

Now we are considering snubber circuit.
So we want to know parastic inductanc between Vin and high side FET's drain.

The details can be checked at bellow the area colored in red.

Do you have Lp2 information of TPS54425?
We guess typical value is 5nH, but accurate information knows only you.so please help us.

Best regards,
akashi

  • 0
    TI__Genius 10090 points

    Hi Akashi,

    We recommend to determine the RC snubber by experiment because the parasitic inductance of PCB wire also affects. You can use 5nH to do a rough calculation. Thanks.

    Best Regards,

    Shipeng

  • 0 in reply to Shipeng Cheng
    Prodigy 120 points

    Hi. Shipeng

    Thanks your reply.
    As you know most important point is using actual measurement result to make snubber circuit.

    But we have no environment that is mounted TPS54425 in our company.
    so it is difficult to estimate parts size for land pat before generate PCB.
    In our AW design plan, parastic inductor between Cin and Vin is 340pH.
    So,I would like to know how large the internal parasitic inductance is.

    Thanks your greathelp.

    Best reagrds,
    akashi

  • +1 in reply to michihiro akashi
    TI__Genius 10090 points

    Hi akashi,

    Sorry we don't have this data. The resistor size depends on its power loss. But the power loss on resistor depends on the Csnub capacitance. The formula is Psnub=1/2*Csnub*Vswpeak^2*fsw.

    Thanks.

    Best Regards,

    Shipeng