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  1. #1
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    Flyback Bias winding dropping out.

    Hello,

    We all know that when an offline, isolated flyback goes "no-load" on its secondary, then it's bias winding drops out.

    ..and then the bias winding is not capable of supplying the PWM controller.

    Is it true , that such "drop-out" of the bias rail, can be avoided by simply adding a large electrolytic capacitor to the bias rail.?

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  2. #2
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    Re: Flyback Bias winding dropping out.

    not completely. It depends on many things: you may increase aux winding turns' number, reduce series resistance, use a schottky diode, reduce consumption of whatever is connected to it: resistive dividers, PWM IC and associated gate charge, etc.
    Increasing the elcap is a viable approach, but not the best.
    bye



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