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UCC28070: UCC28070 PFC MOSFET IDS spike

Red Yen
Expert 4360 points
Part Number: UCC28070


Hi Support team 

pls refer to following for PFC MOSFET IDS, there will be a spike when it is turned on.
Please help confirm that Is this current waveform normal?

addition capacitance across the MOS VDS can be improved,
Are there any other countermeasures that can be used?

  • 0
    TI__Mastermind 34465 points

    Hello Red,

    This current spike may just be due to the discharging of the drain source capacitance as the boost MOSFET turns on.

    Normally a small capacitor is added from the drain to source and this helps reduce the ringing frequency associated with the ringing during the off time.

    The capacitor reduces the high frequency emissions but its disadvantage is that the turn on losses slightly increase at high input voltages.
    You can try reducing the value of the capacitor and/or add a small ferrite bead on the drain.

    This is usually a tradeoff between efficiency and EMI reduction.

    Regards

    John 

  • 0 in reply to John Griffin1
    TI__Mastermind 34465 points

    Hello Red,

    I am closing this post since the question has moved to email.

    Regards

    John