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INA193: Current monitoring anomaly

Rhea Gao
Expert 2350 points
Part Number: INA193

Hi,

The customer is having a problem with the current monitored with INA193.

If the fault occurs, follow the chip and replace the chip.

test record：

The production found too many material anomalies, the current of the original 1A, the actual monitoring only 0.2A. The actual monitoring calculated the current value according to the resistance op-amp ratio.

Because the monitored voltage is not correct, the current calculated after is abnormal.  Help analyze why.

Attached is the schematic design.

INA193 Current monitoring anomaly.docx

Many thanks~

  • 0
    TI__Mastermind 31020 points

    Hi,

    INA193 has an offset spec of 2mV at room temperature, which translates to 1.3A of uncertainty. Therefore the test limit needs to be relaxed in order to improve yield.

    Another note - the test current needs to be higher to get the INA193 output higher than 50mV. It may become an issue down the road. I suggest to use a minimum test current of 3.5A. The corresponding test limit would be (2.2A, 4.8A) to consider INA193 offset alone.

    To test with a low current, and/or with better accuracy, you might want to take a look at INA293A1, which is pin/package compatible. It can be populated directly on the existing PCB.

    Regards, Guang 

  • 0 in reply to Guang Zhou
    Prodigy 10 points

    I'm get you mean. but ,if the current over 3A.IC out must right.

    Vout= I*0.0015*20
    输出电流 理论值 实际测试 Vout相差
    0A 0 0.0017
    1A 0.03 0.004
    2A 0.06 0.032 0.028
    3A 0.09 0.0605 0.0285
    4A 0.12 0.0886 0.0281
    5A 0.15 0.1173 0.0287
    6A 0.18 0.1459 0.0286
    7A 0.21 0.1744 0.0285
    8A 0.24 0.2029 0.0285
    9A 0.27 0.2313 0.0284
    10A 0.3 0.2601 0.0288

    In actual test, 10 test vaule = 9A .....9A test value = 8A.

  • 0 in reply to vengo wu
    TI__Mastermind 31020 points

    Hi,

    That’s exactly what we should expect from the effect of input offset of INA193, ie, you’ll see a constant difference between measured and expected once the amplifier output is in the linear range.

    Regards, Guang 

  • 0 in reply to Guang Zhou
    TI__Genius 16200 points

    The INA281A1 is a drop-in upgrade to the INA193 that has much better offset and does not have the same low VSENSE issue of the INA193.