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INA210 Vref

460822
Genius 4055 points
Other Parts Discussed in Thread: INA210

INA210 ... What is the purpose of Vref?  The data sheet lists it as being set to Vs/2.  Does it need to be a voltage reference or will a resistor divider be adequate?

The requirement is to measure the current through a sense resistor connected to Gnd.  Is connecting Vref to Gnd  correct?

Assume it is powered by 5v, with an gain of 50 and an input of 0.05 v.  Will it output 2.5v with Vref connected to Gnd?

  • 0
    TI__Intellectual 1385 points

    Hello,

    Vref is used to set Vout equal to Vref when the differential voltage is 0V.  Mid supply is where the INA has the best performance.

    Vref can be a voltage divider but should be buffered with an Op-Amp.  The impedance at the Ref pin will affect the common mode rejection.  I would not suggest using just a voltage divider without the buffer Op-Amp.

    Yes, at a gain of 50, Vshunt=0.05V and Vref at GND the Vout will be 2.5V.

    Will the INA output be routed into an ADC?  If so, what type?  Depending on what accuracy you are trying to achieve, a voltage reference and Op-Amp buffer may be required.

    Regards,

    Jamieson Wardall

    Sensing Aplications

  • 0 in reply to Jamieson Wardall
    Genius 4055 points

    If I understand correctly, Vout = (Vin+ - Vin-) * Gain + Vref.  It would be good to include this equation, plus the info you mention ... in the data sheet.

    ...

    Page 13 is misleading as it indicates a resistor divider is ok.

  • 0 in reply to 460822
    TI__Intellectual 1385 points

    Hi,

    Agree on both and will forward that on.

    Regards,

    Jamieson Wardall