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UCC28700 non-isolated AC/DC reference design PMP10937

Eric Chen4
Expert 2370 points
Other Parts Discussed in Thread: UCC28700, PMP10833, UCC28C42

Hi,

I find UCC28700 non-isolated AC/DC reference design -- PMP10937.

www.ti.com/.../PMP10937

But I can't find any design tool for non-isolated application, may I know if I need 15V/1A output then how can modify it through PMP10937?

Thanks your help. 

  • 0
    TI__Genius 9130 points
    Eric,

    I will check to see if there is any app note or design guide available for high-voltage non-isolated buck.

    Meanwhile, you could also look at PMP10833:
    www.ti.com/.../PMP10833

    This is a non-isolated buck from 85-318 V ac input, 12 V @ 1 A output. The input range is wider than you need, but the output is close. This uses UCC28C42 running at ~50 kHz.

    The UCC28700 design PMP10937 could be modified to use similar power stage as PMP10833.


    Thanks,
    Bernard
  • 0 in reply to Bernard Keogh
    TI__Genius 9130 points
    Eric,

    Actually, PMP10833 is already designed for 15 V output @ 1 A - I was mistaken.

    So you could use that design.


    Alternatively, the original designer of PMP10937 sent me his design calculations.

    To convert to 15 V @ 1 A, you would need to change the current sense resistors R5 & R7 to approx. 0.3 ohm each (0.15 ohm net). You will need an inductor of approx. 30 uH, rated to at least 5.5 A peak (saturation rating). To change the output voltage from ~18 V to ~15 V, R3 would change to approx. 22 k-ohm.

    You will also need to use a different diode D4, FET Q1, filter choke L1 that are rated for the higher current.

    Input and output caps C3, C4, C5 will also need to be increased for the higher power level.


    Thanks,
    Bernard