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INA260: Current register reading is always -1.250000, even though I'm measuring 0.42mA with ampermeter value

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Replies: 4

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Part Number: INA260

Hello,

I hope someone would help me solving that issue:

For checking the I2C communication between the MCU and the INA260 , I write (0x63FF) to the configuration register and read it back and get 0x63FF. So, it's working.
Now, I read th Manufacturer ID and I get 0x5449. This is correct, too.

From the current register I'm reading -1.250000. 
I measured the current through the shunt resistor and i's 0.42mA or 0.22mA depending on the resitistor in series with the LED.

Thanks for your help
Awal

  • Hello Awal,

    Thanks for choosing TI. Are you reading -1.25mA or -1.25A? The INA260 has an input offset current (Ios) of +-1.25mA typical (+-5mA maximum), which means you cannot expect the device to measure any current less than 5mA. In fact you cannot expect any reasonable accuracy for current less than 50mA. If current is 50mA, the INA260 measurement will have typically 2.5% error (10% error maximum) and this error is exclusively due to input offset current.

    Sincerely,
    Peter Iliya
    Current Sensing Applications
  • In reply to Peter Iliya:

    Hello Peter,

    thanks a lot for your quick reaction.

    In fact, I'd like to measure currents having 30mA max.
    So, now I understand, I cannot use the INA260.

    So, which solution would you propose for measuring currents from 0 - 30 mA ?

    Best regards

    Awal

  • In reply to M. Awal Mamouda:

    Hello Awal,

    You could look at the INA210. You will want a device with the lowest input offset (Vos) as possible. You can also refer to one of these designs as well for more ideas.

    TIPD135 - 10uA-100mA, 0.05% Error, High-Side Current Sensing Solution Reference Design
    http://www.ti.com/tool/TIPD135

    TIPD156 - Low-Drift Bidirectional Single-Supply Low-Side Current Sensing Reference Design
    http://www.ti.com/tool/TIPD156

    TIPD104 - Current Sensing Solution, 10uA-10mA, Low-side, Single Supply
    http://www.ti.com/tool/TIPD104

    TIPD129 - 0-1A, Single-Supply, Low-Side, Current Sensing Solution
    http://www.ti.com/tool/TIPD129

    Here's a little article discussing error with low current measurments:
    e2e.ti.com/.../3593.how-vos-and-ib-affect-small-current-measurements

    Sincerely,
    Peter Iliya
    Current Sensing Applications
  • In reply to Peter Iliya:

    Hello Peter,

    thanks a lot for your help !

    Best regards
    Awal

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