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TLV709: how much current does the FB pin need to see on the adjustable version to regulate properly

Shawn Workman
Genius 15180 points
Part Number: TLV709

Tool/software:

Looking at the adjustable version or the TLV709 and need to have the lowest current draw possible. So want to use the largest values for the resistor divider possible. Output is 2.5V and need to minimize the current draw through the divider, but need to maintain regulation and maintain at least 2% accuracy. 

  • 0
    TI__Genius 13490 points

    Hi Shawn,

    Choose resistors R1 and R2 to allow approximately 1.5μA of current through the resistor divider. This is merely a design guideline, and you can go lower than 1.5μA if you understand the tradeoffs.

    • Lower than 1.5 µA:
      • Accuracy error increases (IFB / IDIV). Example: at 1 µA, 40 nA leakage introduces 4 % VOUT error worst-case.  The high-impedance node is more sensitive to coupled noise.
      • Startup can become slightly slower because the divider charges through a very high R.
    • Higher than 1.5 µA:
      • Wastes a bit more static current but improves accuracy and noise immunity.
      • No negative impact on stability as long as the output capacitor and ESR stay within the recommended region of the datasheet’s stability curves.

    I hope this helps

    Ishaan