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SN6501: 2-output by SN6501

Guru 11170 points
Part Number: SN6501

Hello E2E,

Please see the attached file. This is customer's idea.
They thinking that can build to 2-output fly-back dc/dc using the SN6501.
I think it is impossible.
Please let me know TI's opinion.

Regards,
ACGUY

  • Hi ACGUY,

    Which voltage outputs is our customer trying to achieve? This may be possible, but performance will be a concern. Current capability of each output with this topology is limited since the output capacitor is only being charged 50% of the time. Additionally, the loads on each output must be balanced (equal current draw) to prevent transformer saturation. Please encourage our customer to share test results and design requirements.

    Multiple-output topologies can be realized using layouts in the SN6501 datasheet or multi-winding transformers like Wurth Elektronik's 750316669. Schematics shown below:

    From SN6501 datasheet:


    From 750316669 datasheet:


    These are recommended solutions to achieving multiple outputs, but if our customer pursues their idea, please let them know we are willing to help. Feel free to also send me a request to connect if sharing schematics privately is necessary.


    Thank you,
    Manuel Chavez

  • Hello Manuel,

    Thank you for your detail advice. Customer's requests are follows;
    - Primary : Vin = 5V,
    - Secondary : Out1 = 5V/10mA, Out2 = 5V/10mA,
    - Isolated between Primary-side and Secondary-side,
    - Isolated between Out1 and Out2.
    In this case, I think flyback is better than push-pull.

    Please let me know your opinion.

    Regards,
    ACGUY
  • Hi ACGUY,

    I have not seen multi-winding transformers that are isolated on the secondary outputs for either flyback or push-pull configurations before, but our customer's preferred transformer vendor may be willing to make a custom part.

    Since these are low-current requirements, the SN6501 is capable of driving two separate isolation transformers connected in parallel which would have secondary sides that are isolated from each other. Please refer to the schematic below, and let me know if this is something our customer will consider.




    Thank you for your time,
    Manuel Chavez

  • Hello Manuel,

    Thank you for your corperation. I will suggest your idea to customer. I will feed back customer's opinion about it to you in a fewdays later.

    Thank you!
    ACGUY

  • Hi ACGUY,

    That sounds great! I will await your response.


    Best,
    Manuel Chavez