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Original question:

TPS51206: VTT behavior at power up

TPS51206: VTTSNS Connection

Atsushi Takahashi
Expert 1100 points
Part Number: TPS51206

Hi Team,

The data sheet, 8.2.1.2.5 VTTSNS Connection section, says as bellow.
"Consider adding a low-pass R-C filter at the VTTSNS pin in case the ESR of the VTT output capacitor(s) is larger than 2 mΩ.The R-C filter time constant should be approximately the same or slightly lower than the time constant of the VTT output capacitance and ESR."

What is the purpose of having a time constant here?

Best Regards,

  • 0
    TI__Mastermind 19080 points

    Hi Atsushi,

    The time constant effects how the feedback loop responds to changes at the output. Speed of response time has an inverse relationship with the consequences of time constant.. The goal for this feedback loop is to have a fast response to VTT changes while also filtering out high frequency content, so the feedback loop sense point needs to have a faster time constant than the output (or at least a matching time constant).

    Regards,

    James