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LM5116: The waveform of HO and LO is abnormal

Hope Chen
Expert 1030 points
Part Number: LM5116

1,SPEC:INPUT:30-80V;  Output:9V/3A

2,The SCH and waveform of HO and LO is as below

3,Question：a: The out waveform of HO and LO has burr interference

                       b: The high Mosfet and Low Mosfet have directed in the  each cycle, and Cause mosfet heating

  • 0
    TI__Mastermind 21720 points
    Hope,

    Am I correct in assuming that the yellow waveform is the switch node and the blue signal is LO? Also how hot are the FETs getting?

    Assuming that there is some cross conduction between the MOSFETs there are a few options.

    1. Reduce the gate resistance on the low-side gate.
    2. Add a diode in parallel with the gate resistor to decrease the turn-off time of the MOSFET.

    Let me know if you need anything else.

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Expert 1030 points
    Dear Garrett,
    Thanks for your reply first
    The yellow waveform is HO and the blue is LO. I will add try your suggestion
    I think the issue due to dead time,which will lead to the mosfet of High-Side and low- side conduction directly,so that the mosfet will be heat
    Thanks a lot