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LM5143-Q1: Schottky Diode Function

Dylan You
Intellectual 2630 points
Part Number: LM5143-Q1
Other Parts Discussed in Thread: LM5143

Dear Teams,

My customer is using LM5143. Could I ask what is the purpose of using the schottky diode in this reference design? This picture is coming from Navida's reference design.

Thanks!

Dylan

  • 0
    TI__Guru 53802 points

    Hi Dylan,

    This is an antiparallel diode that conducts during the deadtime. It's really not required for the LM5143 as the deadtime is so short.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Intellectual 2630 points

    Hi Timothy,

    Thanks a lot for your reply! If the deadtime is long enough, then this antiparallel diode will be useful, am I right? In my opinion, this diode can reduce the switching losses of MOSFET, am I correct?

    Thanks!

    Dylan

  • 0 in reply to Dylan You
    TI__Guru 53802 points

    Hi Dylan,

    I doubt the diode will conduct much during the deadtime as the current takes time to commutate from the FET's body diode to the Schottky (limited by parasitic inductance and the small difference in voltage between the two diode drops). Also, it adds capacitance and leakage current at hot, both of which reduce light-load efficiency. We did not include it in the EVM, but you are free to try it on your design to see if it makes a difference.

    Regards,

    Tim