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INA219: Measure current higher than actual current

Jeff YANG
Mastermind 9065 points

Part Number: INA219

Tool/software:

Hi,

We have occur measure current higher than actual current.

We use PD controller to read INA219 reads ~7A, but we us current probe only measure ~5A.

But in most condition the current is normal. I've check schematic and layout seems no abnormal.

Our Gain set to /8, (PG0/PG1=1).

Do you have any idea for this? Thank you!

Jeff

  • 0
    TI__Mastermind 30805 points

    Hello Jeff,

    The schematic and layout both look fine to me as well. To debug this, follow these steps:

    During a time with the unexpected result:

    1. Measure the voltage between IN+ and IN- directly on the pins of device.
    2. Compare this measurement to the result from the voltage register.
      1. This will help confirm if the voltage is getting changed before the device, or a problem with communication or result conversions/current calculations.
    3. If the results are the same and:
      1. Are different than what you expect, then the the voltage is getting changed before it reaches the device. You will need to debug the PCB to track the error.
      2. Are the value you expect, then there may be a problem with the configuration value, causing the current register to read incorrectly
    4. If the results are different, then then you may have a communication error, or are converting the values incorrectly.

    If the above steps do not help you find the problem, please send me the following to debug further:

    • A readout of ALL register values during the time of the unexpected result
    • The expected current at the time of the register readout
    • The maximum expected current used to calculate the CURRENT LSB and the chosen CURRENT LSB used for the Calibration register value calculation.

    Regards,

    Mitch