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TPS7A7100 - Accuracy

Mike Ulrich
Expert 3110 points
Other Parts Discussed in Thread: TPS7A7100

Hi,

There is a note on the TPS7A7100 that states "The bottom side of feedback resistor R2 in Figure 28 must be in the range of 27 kΩ to 33 kΩ to maintain the specified regulation accuracy."

How does this regulation accuracy vary if you use a R2 value outside this range? Is there an equation to determine this?

Thank You,
Mike Ulrich

  • 0
    TI__Expert 7035 points
    Hi Mike,

    Our rule of thumb is that the feeback current should be 100 times higher than the current going into the FB pin to ensure accuracy. Increasing the resistor values will cause the current in the feedback loop to decrease and can cause a higher inaccuracy. If the resistors are increased too much the variation in the tolerances also begins to have a large effect on the output voltage, which is why the datasheet recommends this value remain within the 27k to 33k range. I have attached a link to an app note that describes the effect on feedback resistors and output accuracy.

    www.ti.com/.../slva423.pdf

    Best Regards,
    Mark