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UCC28740-Q1: The transfer function of UCC28740-Q1

shilin.liu
Prodigy 105 points
Part Number: UCC28740-Q1

Hi，

Can you tell me the transfer function (Vo(s)/VFB(s)) of UCC28740-Q1?

thank you very much!

  • 0
    TI__Genius 15496 points

    Hi Shilin:

    Vo/Vfb=(Vo/vc)*(vc/Vfb) where:

    Vc: Control law (Vcst in Datasheet)

    -(Vc/Vfb)=(Vc/Ifb)*(Ifb/Vfb). Vc/Ifb can be considered a constant value and its value can be found in the Datasheet, Electrical Characteristics (see below) at no load and full load. To estimate Vfb/Ifb check block diagram of Datasheet. You can also get an estimation with Electrical Characteristics.

    -Vc/Ifb

    -Ifb/Vfb

    -Vo/Vc for a Flyback operating in DCM (Discontinuous Conduction Mode) can be estimated using Basso equations.

    Note: I recommend reading Section 8.3.2.10 od Datasheet which explain what is needed to design the Feedback Control section. It gives more insights about the impact of the components in your design.

    Thank you.