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FLYBUCK-DESIGNER: Help Designing Flyback Converter (10V–30V Input, 12V/5V/3.3V Outputs)

Shashank Reddy
Prodigy 20 points
Part Number: FLYBUCK-DESIGNER
Other Parts Discussed in Thread: UCC28740, UCC28910, PMP, UCC25230, UCC28C45, UCC28C43

Tool/software:

Hi TI Community,

I'm working on a project that requires a flyback converter with the following specifications, and I would appreciate any guidance or recommendations on TI parts, transformer design, and overall architecture.

 

  • Input Voltage: 10V to 30V DC

  • Outputs:

    • 12V @ 2A

    • 5V @ 4A

    • 3.3V @ 2A

  • Topology: Isolated Flyback

  • Flyback Controller IC: I'm looking at parts like UCC28740, UCC28910, or any other TI-recommended controller for this power level and voltage range.

Questions:

  1. Which TI controller IC would you recommend for this multi-output isolated flyback design (with wide Vin)?

  2. Are there any reference designs or PMP examples close to these specs?

  3. Should I regulate the 5V or 3.3V rail for best overall accuracy?

  4. Is there a recommended method to post-regulate the 3.3V/5V outputs if I regulate only one rail directly?

Thanks in advance,
Shashank Reddy
Hardware Design Engineer

  • 0
    TI__Guru* 85816 points

    Hello,

     

    The UCC28740 and UCC28910 need a startup voltage of roughly 21 V, so they will not work in your application because the 10 to 30 V input is too low.

     

    I searched TI’s website and found the UCC25230 for a fly-buck but it’s current capability is too low for your application.

     

    I found the UCC28C43 and UCC28C45 on ti.com that is a fixed frequency PWM controller that has turn on VDD UVLO of 8.4 V and turn off 4.6 V.  This controller will work for a multi output flyback converter that will meet your power requirements.  Fly-buck is not mentioned in the data sheet however since it is a multipurpose PWM controller you could possibly get it to work in that configuration.

    If you have any questions on the UCC28C43/5 devices or how to use them in your application, please repost in the e2e with the part numbers in the thread title.  This way the appropriate applications engineer can help you with your design/questions.

     

    Regards,