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TPS74801 feedback resistor value

K. Sasaki14
Guru 10200 points
Other Parts Discussed in Thread: TPS74801

In TPS74801 datasheet P.11, there is a description of the following.

"In order to achieve the maximum accuracy specifications, R2 should be ≤ 4.99kΩ."

Why is this?

I would like to know the reason why R2 should be ≤ 4.99kΩ.

  • 0
    TI__Prodigy 615 points

    Hi Kohei

    To ignore the IFB current, the basic formula of the output voltage is blow


    The real situation is that

     

    If the R2 is so large that the IFB may affect the Vout.

    We can find the IFB current in datasheet ELECTRICAL CHARACTERISTICS

     

    So we can calculate that    . It will not affect the Vout.

    To avoid the IFB affecting the Vout, The value of the R2 should not be greater than 4.99kΩ.

    Best Regards

    Hisen