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TPS7A88: Feedback Resistor Values

Part Number: TPS7A88

Dear, Sir.

My customer is considering to set the freedback resistor values, R1/R2, R3/R4, to

be more smaller values for the fine tuning of output voltage.

The datasheet described the current though R2, R4 > 5uA.

1) Is it no problem to set more smaller values, R1/R2, R3/R4 to maitain >5uA?

2) I suppose the side-effect would be current consumption through the resistor divider

    network. I wonder it was correct?

3) If you find other side-effect or concern, Please let us know.

Please give your advice.

Best Regards,

H. Sakai

  • Hello Hideyuki,

    I am working your question and will reply within 2 business days.

    Thanks,

    - Stephen

  • Dear, Stephen-san. 
    Thank you so much for your kindly reply. 
    They are considering the review of resistor value for 3.3V output. 
    And the concrete value as candidates are below; 
    1) R1 / R2 = 7.5kohm / 2.4kohm
    2) R1 / R2 = 75kohm / 24kohm
    3)If you have more better combination, Please let us know. 
    Best Regards, 
    H. Sakai
  • Hello Hideyuki-san,

    You are correct, it is no issue to use resistor values which provide larger current draws above 5uA.

    If the customer wishes to use 0.1% tolerance resistors, then 2.4kohm and 7.5kohm are available.
    If the customer wishes to use 1% tolerance resistors (E96 series) then the following may be acceptable choices:

    R1/R2 = 9.31kohm / 3.01kohm, Vout_nom = 3.27V, Iout = 265uA

    R1/R2 = 10.7kohm / 3.4kohm, Vout_nom = 3.318V, Iout = 235uA

    R1/R2 = 35.7kohm / 11.5kohm, Vout_nom = 3.28V, Iout = 695uA

    Thanks,

    - Stephen