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    Flyback Transformer Design (48V in, 12v out, how to layer turns, leakage inductance)

    Hi,

    I'm working on a high frequency flyback power supply. Specs approx:
    1MHz sw freq
    Vin 48V
    Vout 12V
    Power out 10-20W

    My questions are regarding the transformer.

    1. I have decided on a core, windings etc. I have a 2 layer primary and 2 layer secondary.
    What would generally be the best way to layer this?
    I was thinking 1 layer of primary first but would it be better to have.....
    1. 1 layer pri, then 1 layer sec, then 1 layer pri, then the final sec. or
    2. 2 secondary layers directly together sandwiched between the two single primary layers.

    Is there a rule of thumb for leakage inductance of a well designed (& manufactured) flyback transformer - perhaps as a percentage of the main inductance?

    •   Alt12th January 2017, 10:10

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  2. #2
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    re: Flyback Transformer Design (48V in, 12v out, how to layer turns, leakage inductance)

    1. 1 layer pri, then 1 layer sec, then 1 layer pri, then the final sec. or
    Leakage inductance will be reduce ¼ th of regular primary secondary winding but inter winding capacitance will be double. Wave form rigging will be very less

    2. 2 secondary layers directly together sandwiched between the two single primary layers.
    Leakage inductance will be reduce 1/2 rd of regular primary secondary winding and less inter winding capacitance . Wave form rigging also less
    Better to go ahead with second option (2.2)

    (Inter winding capacitance are important if high voltage application)


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    •   Alt12th January 2017, 10:39

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  3. #3
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    re: Flyback Transformer Design (48V in, 12v out, how to layer turns, leakage inductance)

    Do you have any additional requirements, like creepage distance? I don't think so, since your primary is relatively low voltage. But please check.
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