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Voltage Reference TLV431A

Brad Ricke
Prodigy 20 points
Other Parts Discussed in Thread: TLV431A, TPS61070

I am currently designing a battery management system and need to get the voltage off of the battery cells so it can be compared in a microcontroller. I am trying to use the TLV431A to set a 3.7 V reference level for the microcontroller. I want the output to have a constant 3.7 V DC value while the battery is anywhere from 2.2 V to 3.7 V. I am using Figure 2 on the datasheet to try to get the desired output, but when I hook up the circuit, the output voltage simply follows the input voltage. Please help! Thank you!

  • 0
    TI__Guru*** 140126 points

    Hello Brad Ricke,

    What values did you chose for the resistors in figure 2?
    What range of input voltage did you test?

    The input voltage must be greater than 3.7V to see an output voltage that remains constant with VIN change.

    Regards,
    Ron M.

  • 0
    TI__Intellectual 2770 points

    Hello Brad,

    Unfortunately the TLV431A cannot be used to get a Vref higher than the input voltage.

    If you are looking for a way to get a higher output voltage you should have a look at our Boost-Converters or Charge-Pumps. Maybe TPS61070 could be a good start for a search.

    Best regards

    Thomas

  • 0 in reply to Ron Michallick
    Prodigy 20 points

    Thanks for the fast reply. I'm looking to have the value stay constant at 3.7 V even when Vin goes as low as 2.2 V. I was using a 22k for R1 and 11k for R2 (10k and 1k in series) . I tested the input range from 1.5V to 6V.  If this component does will not work for this kind of application, do you have any suggestions on a different component to use? Would a voltage regulator with an incorporated boost seem like a better option here?

    Thank you!

    Brad