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UCC28063A: SCH review and Vo drop during light load

Part Number: UCC28063A
Other Parts Discussed in Thread: UCC28063

Hi Sir,

May I have your help to review the UCC28063 SCH and Design calculator in the attachment?

Currently, we facing a output voltage drop issue in light load, Vout will drop from 388V to 382V if we increase load from 0A to 0.2A.

May I learn from you that how could we improve this output voltage drop during light load?

Thank you.

Best regards,

Edward Chen

PFC schematic value from Cincon.pdf

UCC28063 Design Calculator from Cincon.xlsx

  • Hello Edward,

    I just wanted to let you know that I am in process of evaluating this inquiry.



  • Hello Edward,

    I reviewed the design calculator and it looks like the compensation that were chosen for Cp and Cz used are much smaller than the calculator recommended. I believe you are having a load regulation issue due to not having enough DC gain in the voltage loop. I would recommend picking values for Rz, Cp and Cz closer to the values that the design calculator recommends.