TPS7A8300: PSRR issue

justifice zhou

Intellectual 400 points

Part Number: TPS7A8300

I'm reading this article

Understanding power supply ripple rejection in linear regulators

PSRR=20log(Ripple input/Ripple output)=20log(Av/Avo)

But why Ripple input/Ripple output=Av/Avo, I don't understand that.

over 1 year ago

0 Nick Butts over 1 year ago

TI__Mastermind 43585 points

Hi Justifice,

Are you asking why PSRR is calculated as ripple input/output instead of ripple output/input? If so, it is simply so that the PSRR is a positive value instead of negative. There's no numerical difference besides the sign change.

Regards,

Nick

0 justifice zhou over 1 year ago in reply to Nick Butts

Intellectual 400 points

No, I'm asking why PSRR=Av/Avo.

0 Nick Butts over 1 year ago in reply to justifice zhou

TI__Mastermind 43585 points

Hi Justifice,

It is the result of a small-signal analysis on the pass device and control loop.

Regards,

Nick

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TPS7A8300: PSRR issue