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UCC28700: Full-Bridge Isolated Boost Topology Controller Recomendation

Hayden_Hast
Intellectual 1515 points
Part Number: UCC28700
Other Parts Discussed in Thread: PMP10200

Hi Team,

I need a controller recommendation for a full-bridge isolated boost topology, similar to what is shown below.

The current specs I have are the following...

  • Input voltage is varied by a mechanical component and can range from 33V to 400V. These are line-to-line voltages.
  • Output voltage should be 28-33V with some flexability
  • Output current will be 2-3A

I've proposed a flyback topology using the UCC28700 (such as PMP10200) but due to the wide Vin range and a desire for a linear control-to-out function the customer has requested a full-bridge boost proposal.

Isolated_Boost_Top.docx

Thanks for the support,

Hayden

  • 0
    TI__Expert 3095 points
    Hi Hayden_Hast,
    I am not aware of any controller suitable for this topology.
    One important difficulty, is that to avoid saturating the transformer you must either turn OFF all the switches or leave the switch pairs oscillating with no over-lap. Clearly turning OFF all of the switches can only be done after the inductor current has fallen to zero.
    Since it is a boost topology I do not think that it has a linear control to out function. It should be 1/(1-d).
    Thanks
    Joe Leisten
  • 0 in reply to Joe Leisten
    TI__Intellectual 1515 points
    Hi Joe,

    Thanks for the quick response and confirmed my suspicions. If you and the team have any other ideas (other than the Boost topology) given the circuit inputs I provided, feel free to share them.

    Regards,
    Hayden
  • 0 in reply to Joe Leisten
    Prodigy 210 points

    Hi Joe - yes, the Boost transfer function is 1/(1-d), but when you couple the widely-varying input voltage you get a ~linear DC vs Vin, instead of a ~1/x DC vs Vin curve like you would get with a Buck, for instance. This isn't a requirement, but wanted to stay away from the extreme areas of the "1/x" (vertical and horizontal asymptotes) for controllability reasons. The challenge here is the ~20:1 input range. Still open to any suggestions you might have.

    Thanks, Kevin Spahr

  • 0 in reply to Kevin Spahr
    TI__Expert 3095 points

    Hi Kevin Spahr,

    Thanks for taking the time to clarify your requirements over the phone.

    Hopefully your query has been addressed and we can close this post.

    Feel free to open another if further questions arise.

    Regards

    Joe Leisten