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CSD19533KCS: peack diode recovery dv/dt

John11513
Expert 5720 points
Part Number: CSD19533KCS

Hi experts,

I noted all of our MOSFETs do not have "peak diode recovery dv/dt" spec. How can I get the spec of CSD19533KCS?

Thank you!

John

  • 0
    TI__Mastermind 37950 points

    Hello John,

    Thanks for the inquiry. As you point out, TI does not spec peak diode recovery dv/dt in our FET datasheets. I have seen this calculated as follows:

    dv/dt = VTH / (RG x CGD)

    Using CSD19533KCS datasheet parameters the calculated peak diode recovery dv/dt is:

    dv/dt = 2.8V / (1.2Ω x 9.6pF) = 243V/ns

    This is not tested nor specified and is therefore not guaranteed. Please let me know if you have any questions.

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    TI__Expert 5720 points

    Hi John,

    Thank you for reply.

    I think what you calculated dv/dt capability is based on miller cap (CGD) mechanism. However there is another dv/dt induced fault turn-on mechanism, parasitic BJT turn-on due to recovery current through body diode induced by high dv/dt. As I known this second mechanism results much lower dv/dt capability.

    Regards,

    John

  • 0 in reply to John11513
    TI__Mastermind 37950 points

    Hi John,

    Yes, there is also the parasitic NPN bipolar to consider. The calculation is as follows:

    dv/dt = VBE/(CBD x RB)

    We have not characterized our FETs for these parameters. I consulted with one of the designers and the FETs are designed to minimize the value of RB in order to prevent turn-on of the parasitic BJT. Standard reliability data shows the device to be stable under normal operating conditions. Generally, we are most concerned about Cdv/dt (Miller capacitance) turn-on leading to shoot-thru and potentially destroying the device. Charge ratio, Qgd/Qgs < 1, to prevent Cdv/dt induced turn-on of the FET. Beyond that, we do not have any additional data to share.

    Thanks,

    John