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TPS7A85: About feed-foward capacitor

K. Sasaki14
Guru 10200 points
Part Number: TPS7A85

Can we use TPS7A85 without feed-foward capacitor?
If it is possible, is it OK that FB pin is open?

I think this is possible, however Cff is recommended for LDO performance.

Best Regards,
Kohei Sasaki

  • 0
    TI__Expert 4435 points

    Hi Kohei,

    Datasheet says a feed-forward capacitor (Cff) is not required for regulator stability, but using Cff will improve transient, noise, and mid-band frequency PSRR performance. Datasheet load transient, output noise voltage, and PSRR are specified with Cff = 10nF. 

    You can use TPS7A85 without Cff and leave FB pin open, if the transient, noise, and PSRR performance without Cff meets your requirements. 

    See the application report "Pros and Cons of Using a Feed-Forward Capacitor with a Low Dropout Regulator: http://www.ti.com/lit/an/sbva042/sbva042.pdf

    Best,

    Eric