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TPS61099: optimize feedback resistor values for lowest power

Expert 5875 points

Replies: 3

Views: 32

Part Number: TPS61099

Hi,

Is there a recommended minimum bias current for the feedback network? I'm trying to minimize the bias current for R1 & R2

without compromising the device function.  In the EVM, the bias current is Vout/(R1+R2)=5V/(1Mohm+0.25Mohm)=4uA.

My circuit Vout=2V so I was thinking of using R1=R2=1Mohm, which means the bias current is 1uA.  Is this too low? Can I go lower?

-Kelvin

  • Hi Kelvin:

    It depends on how accuracy the Vout you expected. Do you have such requirement?

    Below is an application note:Design considerations for a resistive feedback divider in a DC/DC converter. It may help you do the analysis

    http://www.ti.com/lit/an/slyt469/slyt469.pdf

    Best Regards

    Minqiu

  • In reply to Minqiu Xie:

    Minqiu,

    +/-5% accuracy is okay.

    I didn't see a leakage spec for the feedback pin of TPS61099.

    Please advise.

    -Kelvin

  • In reply to Kelvin Le THS:

    Hi kelvin:

    The leakage current is 50nA max. And please search IFB_LKG in datasheet.It should be OK using R1=R2=1Mohm.

    Best Regards

    Minqiu

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