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INA190: Can I use two amplifiers with the same shunt?

Aleksejs Skorodumovs
Prodigy 40 points
Part Number: INA190

I have an application which requires two amplifiers for different resolution.

I plan for both of them to be enabled at all times. 

I'm slightly concerned about connecting them in parallel because of bias currents.

Could you please just confirm that this configuration shouldn't be a problem?

  • +1
    TI__Expert 4110 points

    Hi Aleksejs,

    The input bias current of the INA190 is in the order of nano amps, 3 orders of magnitude smaller than typical input bias currents for similar current sensing devices.

    This is because of its capacitively coupled input stage, which gives it much higher input differential impedance.

    Because the input bias current is so small, having 2 devices using the same shunt shouldn't be an issue even if it means doubling the input bias current seen. 

    You haven't specified what the current range you intent on measuring is which would be helpful in determining if it could potentially cause a problem, but it is very unlikely that the input bias current will cause issues on your measurements using this device. 

    Best Regards,

    Angel

  • 0 in reply to Angel Rodriguez de San Miguel Bermudez
    Prodigy 40 points

    That's what I was thinking. The currents I want to measure range from 1mA to 20A, bias currents shouldn't be a problem. Just wanted to get a second opinion Thumbsup