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UCC28951-Q1: 70V output design

yatao fu
Prodigy 30 points
Part Number: UCC28951-Q1
Other Parts Discussed in Thread: UCC28951, PMP8740

Hi,

I have designed a 20V output power supply using UCC28951. It is successful. The DEMO I am referring to is TIDA-020031.

While I need to design a 70V output power supply. The current is 45A and power is 3000W. Can I use UCC28951 to implement it？If possible, what are the advantages and disadvantages? Is there a suitable DEMO reference available?

At the same time, I would like to inquire about the difference between a center-tap SR and full-bridge SR for 70V output. Which method is more suitable for my design？

Thank you very much！

  • 0
    TI__Guru* 86286 points

    Hello,

    I am reviewing your inquiry and will get back to you shortly.

    Regards,

  • +1 in reply to Mike O'
    TI__Guru* 86286 points

    Hello,

    The UCC28951 can be used for a 3 kW application.  The TIDA-020031 is designed for 3.6 kW.  With a 70 V output is still low enough to where SRs can be used.

    The following link will bring you to an application note that goes through the step by step design process of a FSFB using the UCC28951.  There is also a link inside the application note to an excel design tool that goes along with the application note.  I believe these design tools will help you with your 3 kW design.

     https://www.ti.com/lit/pdf/slua560

    The advantages of using an SR full bridge is bein able to use lower voltage FETs and you do not need a center tap on the secondary of the transformer. 

    The SR full bridge does have some disadvantages when compared to the two SR center tap solution.

    1. You require 4 SRs instead  2.

    2. The SR conduction losses will be 2X.

    3. Driving the SR bridge is more complicated.

    Regards,

  • 0 in reply to Mike O'
    Prodigy 30 points

    Hi,

    Thank you very much for your answer. It has been very useful to me. I also want to ask what are the advantages and disadvantages of TIDA-020031's rectification method compared to PMP8740's rectification method？They used the same number of SR.

    TIDA-020031

    PMP8740

  • 0 in reply to yatao fu
    TI__Guru* 86286 points

    Hello,

    Your inquiry is under review and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 86286 points

    Hello,

    This is an interesting question.  Using a current doubler (schematic 1) in a phase shifted full bridge verses a voltage doubler (schematic 2).

    Schematic 1 uses two inductors that operate at the same frequency as the primary H Bridge.  The inductors will have inductor ripple current cancelation which can reduce the RMS current in the output capacitor similar to an interleaved buck converter.

    Schematic 2 uses one inductor and will have higher boost capacitor RMS current.  However, the design requires one less inductor and would make the layout easier.

    Regards,