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UCC28063: UCC28063 phase issue

Jerry Hsueh
Expert 2730 points
Part Number: UCC28063

Hi

We want to use UCC28063 work in interleaved PFC, below two pictures  are the MOS Vds waveforms measured at 100W, respectively, in the trough and the crest. There is no 180 degree of intersection between A and B phase.

What is the reason? Is it related to the TSET resistance, or the ZCD parameter or...?

Thank you.

Jerry

  • 0
    TI__Mastermind 34465 points
    Hello Jerry,
    This is most likely a pcb layout issue related to the ZCDA, ZCDB ,TSET pins.
    These pins are very sensitive to noise pickup and the decoupling capacitors on ZCDA and ZCDB should be connected directly to the AGND pin.
    Also the TSET resistor should be tied directly from the TSET pin to AGND.
    Any noise present on the PGND will cause loss of 180 degs phase shift if these pins are connected to PGND.
    Regards
    John