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INA219: offset current value through I2C when real Iout=0A

Johnny Guo
Expert 4910 points
Part Number: INA219
Other Parts Discussed in Thread: INA233

Hi, team,

If INA219 real current through shunt is Iout=0A, we can read the current is xA through I2C. And when Iout increases to yA, read current value is (x+y)A.

1. Is it caused by ADC shunt offset as shown below?

2. How to calibrate the offset?

Thanks.

Johnny

  • 0
    TI__Expert 4915 points

    Hi Johnny,

    Thank you for posting on the E2E Forums.

    Yes, the readings are due to the device offset and, if your application requires that level of precision, will need to be subtracted from the total read current.

    There is no way to cancel the offset. The options are as below:

    • At startup with I = 0A, save the reading as a constant and subtract it from all future measurements
    • Switch to the INA233, which is a zero offset part