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Original question:

INA125 single supply issue

INA125: ina125 VRefBG pin13

Anthony Crimin
Prodigy 20 points
Part Number: INA125

I am using the ina125 chips to make a load cell with six channels and the bridges have different bridge voltages gain etc, the ina125 chip is good as it integrates everything. I have a few questions.

1-what is the VrefBG pin 13 for it does seem to be to supply a reference voltage to an external circuit - I have not understood the datasheet explanations - can a set the bridge voltage to what I want?

https://e2e.ti.com/support/amplifiers/f/14/t/431689?INA125-single-supply-issue

2-IIs it possible to connect the to use a potentiometer to change the input into the IAref pin 5 to set the initial bridge voltage with the required offset

  • 0
    TI__Mastermind 47576 points

    Hi Anthony,

    Question:

    can a set the bridge voltage to what I want?

    Answer:

    If you want to use the precision voltage reference for the input bias of INA125, you have four choices, namely 1.24V, 2.5V, 5V and 10V. You may select one of the pin connection in pin 13 for 1.24V, pin 14 for 2.5V, pin 15 for 5V  or pin 16 for 10V of precision reference. Your positive input voltage rail has to be greater than the reference voltage you selected. 

    Question:

    Is it possible to connect the to use a potentiometer to change the input into the IAref pin 5 to set the initial bridge voltage with the required offset

    Answer:


    IAref pin has to be stable low impedance voltage reference against temperature, noise and time in drift. If you want to use potentiometer, you have to connect the resistor divider through a voltage buffer. Output of voltage buffer will provide you with low impedance requirement. IAref pin is connected to 30kOhm trimmed resistor internally at V- point in A2, see the first page of the datasheet, see the attached image.

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    Prodigy 20 points

    Thanks for your response it has clarified the set significantly.