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INA190: INA190 vs. INA188 in TIDA-01040

Jerry Chen
Expert 5110 points
Part Number: INA190
Other Parts Discussed in Thread: TIDA-01040, INA188, INA225, PMP40182

Hi,

I saw the input bias current of INA190 is at nA level, which can be ignored in the application of TIDA-01040. When Gain=50, I saw the specified offset(max), offset drift(max), CMRR(min), gain error temperature drift(max) of INA190 are all batter than INA188. Does it mean replacing INA188 by INA190 in TIDA-01040 introduces not only easier power supply, but also higher current measurement accuracy? I ignored the calibration in the system design, just compare amplifier to amplifier.

I'm not sure if the CMRR and gain error specified in datasheets of INA190 and INA188 are the same thing in the same test condition.

My application is high side DC current measurement with 1mohm current shunt, 50A current, 4.2V common voltage.

Thanks.

  • 0
    TI__Mastermind 34060 points

    Hi Jerry,

    I don’t see anything preventing INA190 being used here unless I missed something critical. Aside from the parameters you mentioned, the swing spec is indeed much better for INA190. Depending on the minimum current to be measured, it might be possible to eliminate the -5V supply. The positive supply can use +5V instead of 10V to accommodate the same common mode voltage range. CMRR for both devices are excellent, its error contribution is negligible.

    Have you investigated whether it is possible to remove the SN74LV4053? From error reduction point of view, it might be worth it to bias the INA output at midscale and accomplish level shifting downstream before the ADC. I don’t know the answer, just wondering.

    Regards, Guang

  • 0 in reply to Guang Zhou
    TI__Expert 5110 points
    Hi Guang,
    I knew the resistance of SN74LV4053 will introduce gain error, as the input impedance of INA190 is not as high as INA188. In PMP40182, it used analog mux at REF input of INA225 to make it a bi-directional current sensing.
    The accuracy of TIDA-01040 is 0.05% at 50A on 1mohm shunt with calibration. Without calibration, I saw INA190 is a little more precise than INA188 in my calculation. For this application, INA190 has a smaller offset which dominates the accuracy of this application. Do I miss anything?
    Thanks.
  • 0 in reply to Jerry Chen
    TI__Mastermind 34060 points

    Hi Jerry,

    I think INA190 can be used as is, all you need to do is change the supply and check if the low current range is OK, considering swing and offset of INA190. In the current design, the INA has a dual supply which eliminates swing limitation around 0A.

    I’m not worried about the on resistance of the mux. The question is whether the mux should/can be removed regardless which INA is used. Maybe having the mux doesn’t matter since you’ll need to calibrate anyway.

    Regards, Guang