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UCC28780: Max. Wattage

Hiroshi Doi35
Expert 2845 points
Part Number: UCC28780
Other Parts Discussed in Thread: UCC24612

Hi All,

My customer  want to start evaluate Active clamp.

Specification is,

Input:  AC80V-140V and AC180V-AC276V

Output: DC24V  6A max.  12A peak(200ms)

Without PFC    For no need PFC countries.

Can UCC28780  be used for this specification?

How about UCC28780 wattage limit?

If UCC28780 can not be used, please tell me the type name of recommended Active clamp forward.

Thank you,

  • 0
    Expert 2845 points
    Hi All,

    Some corrections here.
    AC80V-140V and AC180V-AC276V are different model.
    PCB layout , parts, transformer are different --> OK.
    Without PFC but need regulation countries. they can keep the limit by another method.
    Efficiency is most important even make different two boards.

    Thank you,
    H.DOI
  • 0 in reply to Hiroshi Doi35
    TI__Expert 7395 points
    Doi-san,

    Good to hear from you! I hope you are doing well.

    Thanks for thinking of TI here.

    Ucc28780 is a good fit for this application. In general it is mostly targeted for 20w-150w applications. Since the Vout is 24v even at 150w I tend to think it will be better compared to Forward. A forward may he better at that power if Vout was much lower like 12v but ACF as a flyback derivative excels in higher Vout applications like this.

    The only concern I have is the peak power. Ucc28780 can handle up to 150% over power event for 160 ms. Some people over design power stage so you could design for 192w max steady-state power. Some people also try to extend over power timer by playing tricks with Current sense. So for example, just before 160ms, they drop below max opp and then let it go to OPP again and they can provide over power again for almost 160ms. Many audio and printer customers do these tricks.

    What is application here?

    Are you planning on using GaN or Silicon MOSFETS on primary? You may consider using ucc24612 SR controller also here.

    Regards
    John