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UCC28019A: Bias flyback; before PFC or after?

Ras Sharif50
Genius 3455 points
Part Number: UCC28019A
Other Parts Discussed in Thread: UCC28722

Dear All,

i have finished a test of UCC28019A.

i supplied the pfc controller form an external bias.

now i want to add a bias flyback ( UCC28722 PSR flyback ) to the .

i have a questions:

is it true/beter to place the flyback after the PFC or before?

Best Regards,

Ras

  • 0
    TI__Mastermind 34465 points
    Hello Ras,
    The normal system requirement is to design the flyback with a wide range input voltage so that it operated from the minimum of the rectified AC line line to the set point of the pfc bus voltage.
    If you can connect the flyback to the pfc output the flyback will start up and supply a bias voltage to the pfc controller.
    The bypass diode across the boost inductor on the pfc will supply an input voltage to the flyback.
    The pfc then starts up and supplies a high voltage to the flyback.
    This method ensures a seamless power startup sequence.

    Regards
    John