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INA296B4Q - Gain Error Factor

Ana Ilieva
Prodigy 30 points
Other Parts Discussed in Thread: INA240

Hello,

We are using in our schematic your INA296B4Q for current measurement circuit.
In the datasheet I do not see a formula for the Gain Error Factor.
For INA240, the following formula is given:

And I need it for calculating what error our external filtering resistor contributes.
Can you support me with this for INA296B4Q?

Thank you in advance!

  • 0
    TI__Mastermind 30610 points

    Hello Ana,

    The INA296 does not have the same input structure as the INA240.  I believe you will see the biggest error in gain on the model.  This is from the curves on the datasheet of IB vs Vsense.  This will cause a gain error with the filter resistors installed.  I will look into getting an equation but I think the best solution is use the Tina-Model for that error.  Keep in mind adding a filter at the input will cause some mismatch at the inputs causing additional error.  Normally VCM noise is the biggest mismatch that I would see due to the impedance of the capacitors.  If there is no VCM noise and you are only doing a differential capacitor then this is less of an issue.

  • 0 in reply to Javier Contreras4
    Prodigy 30 points

    Hello Javier,

    Yes, I was thinking that the 2 CSA are not the same so it is not a best practice to use the INA240 gain error factor for INA296. Do you have any new information for the Gain error factor equation for INA296? 

  • 0 in reply to Ana Ilieva
    TI__Mastermind 30610 points

    Hello Ana,

    You can use the same equation as the INA240 but replace 3000 with 3250.  Again this is an estimate.

    Regards,

    Javier