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Original question:

UCC28070: Cannot work with load

UCC28070: Gradually lowering the PF value will decrease the input

Gabriel Wang1
Genius 4715 points
Part Number: UCC28070

Dear Expert

Out design is 5KW industrial power .Now we debug the UCC28070 ,when gardually decrease the input voltage 220V to 110V ,and when the input is 160V to 110V the PF value is about 84% , could u help give a suggestion how to inprove the PF value when input a low value ?

Below is sch 

5KW原理图.docx

  • 0
    TI__Mastermind 24375 points

    Hi Gabriel,

    Thank you for the query on UCC28070.

    I do not see the value of inductor in the schematic, but assume it is around 75uH and input voltage is assumed for universal range. I have attached the detailed calculations in the attachment. The following are some of the observations which could contribute to this behaviour.

    1. Rimo should be higher around 25k

    2. R16 and R17 ressitors shows around 10 ohm  combined, It should be close to 16ohms

    3. R71 for Dmax looks wrong. It should be close to 72k.

    4. Consider increasing R10 which the CT reset resistor to a high value. Current value of 10 ohm does not look ok.

    5. Lastly, I would recommend tuning the voltage and current loops as per the attachment.

    Regards,

    HarishPFC_REVIEW.pdf