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PMP9656: modifications for 24V-48V input and 12V/20A

Part Number: PMP9656
Other Parts Discussed in Thread: PMP6547, PMP8861

Hi team,

My customer followed the PMP9656 and successfully built a design for 48V to 12/20A applications.
Now they have a new project, hoping to extend the input voltage range to 24V-48V, but in the original design it was 48V-60V.
Can we modify the design to meet the new specifications? If yes, could you help provide a detailed list of changes? Thanks for your support!

Best regards,
Sam Ting

  • Hello Sam,

    to generate 240W output power w/ a single ended forward converter the input voltage range needs to be tight;
    I would expect your true input range 18V to 60V or even more like 18V to 75V. So your input range is around
    1:3, may be 1:4.

    To get PMP9656 to your input range it's not just a small change, it's a new ground up design,
    needs a new transformer w/ new windings ratio to meet max. duty cycle <65% at low Vin.

    Please have a look at PMP6547 or PMP8861 - but just half of your needed power,
    could be a starting point for your own design.

    Best regards, Bernd

  • Hi Bernd,

    My customer wants to build the design by Webench, 

    Can you comment on whether the selected transformer and output inductor are suitable for the design? Thank you!

    PA0931NL.pdf

    SER2918H-103KL 承认书.pdf

    Best regards,

    Sam Ting

  • Hello Sam,

    such a design can't be built just by Webench, needs power design experience.
    As already mentioned a 240W ACF for wide input voltage range will be tricky.
    Would recommend a push pull converter or a hard switched half bridge.

    See attached power stage analysis of your ACF intention, may be this helps to understand.

    Best regards, Bernd

    ACF_SAM_PwrStg.pdf