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TPS7A85: What R1 and R2 are recommended for Vout=0.82V

Kazuhiko Hirano
Genius 11613 points
Part Number: TPS7A85

Hello,

 

My customer would like to get Vout=0.82V.

If R1=12.4Kohms as the datasheet recommends, R2 is calculated as 496Kohms.

Then this resistive network can not provide 5uA.

From noise and PSRR point of view, and to provide >5uA, what R1 and R2 are recommended?

 

Best regards,

 

K.Hirano

  • 0
    TI__Mastermind 29320 points

    Hello Kazuhiko,

    5 options are provided below, along with 100,000 monte carlo simulations providing you the statistical analysis of each option.
    We recommend using the NR/SS capacitor to filter the bandgap reference noise, and the feed forward capacitor to filter the higher frequency noise, as described in the datasheet (see below).

    R1 R2 Vout Average Vout Standard Deviation
    210 8450 0.819881678 0.002060806
    205 8250 0.819878817 0.002060855
    243 9760 0.819918036 0.002064724
    2490 100000 0.819920003 0.002868345
    3320 133000 0.819969952 0.003361973

    Thanks,

    - Stephen