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UCC21520: To add external diode between OUTA and VSSA, OUTB and VSSB

Eric Lai
Expert 4940 points

Part Number: UCC21520

Hi Expert,

For better negative voltage clamping, we would like to advice the designer to add the shottky diode between OUTA and VSSA, OUTB and VSSB.

Pls advice whether we have the reference design also adopt this usage.

And comment the concern if had.

Best regards,

Eric Lai

  • 0
    TI__Guru**** 189401 points
    Hi Eric,

    Thanks for your question. I've asked my colleague to comment on it. He will get back to you on Monday, Dallas time.
  • 0 in reply to Don Dapkus
    TI__Mastermind 34380 points
    Hello Eric,

    Adding schottky clamps between output and VSS to clamp undervoltage on the outputs is rarely necessary, since the gate driver output MOSFETs will usually clamp undervoltage through the intrinsic diodes. In rare cases or in high-noise environments, schottky clamps can help to protect the gate driver from extreme undervoltage events.

    If the designer's board has space, there is no harm in recommending placing pads for the schottky clamps. However, the design should be tested first without the clamps populated, to ensure they are not adding unnecessary cost for no system benefit.

    Our reference designs do not have schottky clamps on the outputs, because our reference designs are carefully planned to keep undervoltage conditions on the driver outputs low enough that schottky clamps are not beneficial.

    Regards,