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UCC28910: Transformer specification qeustion

Polly Chung1
Intellectual 2110 points
Part Number: UCC28910

Dear team,

My customer has some transformer questions and their specification is as below. Could you please help us to check it? Thank you.

  1. Input 100~240V,Output (6V/1A)
  2. Input 100~240V,Output (5V/1A)
  3. Input 100~240V,Output (7.2V/0.5A)

They used our UCC28910 webench to run simulation and they got those transformer parameters in the following content. Because their PCB size is limited, RM6 core size will be too big. And the transformer vendor suggests them to change core from RM6 to EP15.2. If they change the core, is there any transformer parameter that we should keep the same besides Lp and turn ratio? I also attach two core specifications at the end of post. (Ae@RM6: 37.5mm2; Ae@EP15.2: 30.76mm2.)

B65807P0000R049 (6V/1A)

Lp= 1.458 mH

Turns Ratio(Nas)=13:4

Turns Ratio(Nps)=51:4

Npri= 51.0

Naux= 13.0

Nsec= 4.0

 

B65807P0000R049 (5V/1A)

Lp= 1.851 mH

Turns Ratio(Nas)=15:4

Turns Ratio(Nps)=59:4

Npri= 59.0

Naux= 15.0

Nsec= 4.0

 

B65807P0000R049(7.2V/0.5A)

Lp= 2.352 mH

Turns Ratio(Nas)=14:5

Turns Ratio(Nps)=56:5

Npri= 56.0

Naux= 14.0

Nsec= 5.0

B65807P0000R049.pdf

Thanks again

Best Regards,

Polly Chung

  • 0
    TI__Genius 9710 points

    Dear Polly,

    Thanks for promoting our solution.

    If you use smaller Ae, you should double check the delta B.

    Smaller Ae will cause higher delta B, which will cause higher core loss.

    Also, you need to double check saturation point, different core material have different saturation point. 

    If you have other questions, please feel free to let me know.

    Best Regards

    Kevin

  • 0 in reply to Kuan Wei Chen (Kevin Chen)
    Prodigy 10 points

    Dear Kevin,

    Thanks for your reply.

    I'll choose a core that AE near RM6.

    Is there any transformer parameter that we should keep the same besides Lp and turn ratio?

    Jerry

  • 0 in reply to Jerry Hsu46
    TI__Genius 9710 points
    Dear Jerry,

    Thanks for interested in TI's solution.
    You also need to use suitable core material for the transformer.
    In addition, I will suggest you to calculate the transformer's core loss and copper loss, if you want to optimize the transformer design.
    Usually, transformer will have best performance during core loss equal to copper loss.

    I hope this help your design.
    If you have other question, please feel free to let me know.

    Best Regards
    Kevin