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Help select topology 150-300W 0-50V

Other Parts Discussed in Thread: PMP10215, LM5021, LM5039, PMP10110, UCC28951, PMP7391, UCC2894

Hello,

any topology reccomendation? 

DCin = 390V

variable output voltage 0-50V

i was thinking about active flyback.

It should be ZVS / ZCS. For best efficiency. Thanks

  • Hello Ahmed,

    300W is quite a lot for a flyback topology, even a lot for a single ended forward topology.
    Would not recommend push pull due to voltage stress at FETs and only half of the winding
    is used.

    A two switch forward or a hard switched half bridge is cost effective and suited for variable Vout.
    PMP10215 shows a two switch forward using LM5021
    PMP10110 shows a hard switched half bridge using LM5039

    Both designs are close to your needs, best regards, Bernd

  • Hello,

    are there any other options with zvs? Thanks for your time. I apreciate it.

    Have a nice day!

  • Hello Ahmed,

    300W is too much power for ACF; an interleaved ACF using two power stages is not that cost effective;
    LLC can't handle the 0V to 50V output.
    So if ZVS is a must go for a small PSFB using UCC28951 - but you buy for four FETs on primary side.

    Best regards, Bernd

  • Ok,

    and 150W variant with active clamp forward is ok?

    thanks

  • Hello Ahmed,

    please check i.e. PMP7391 using UCC2894, that's a 150W+ Active Clamp Forward powered out of PFC; BUT:
    for variable output voltage 0..50V you won't get the 150W at 1V output voltage, this would result in 150A load current.

    For selecting the windings ratio to achieve reasonable duty cycle you need to watch the drain voltage of primary FET;
    to use a 800V or 900V FET duty needs to be a bit smaller. Please verify attached PDF.

    Best regards, Bernd

    ACF_Ahmed.pdf