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Original question:

INA818: Offset Long term stability

INA818: offset voltage drift compared to INA188 @ 85C

Jerry Chen
Expert 5110 points
Part Number: INA818
Other Parts Discussed in Thread: INA188,

Hi team,

I saw INA818 has a smaller initial offset than INA188 at 25C. Considering the drift under 85C, is the total offset still smaller than INA188? 
I also saw discussion about long term drift https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/881626/opa2189-long-term-stability/3261460#3261460 . I think INA818 might be worse than chopper technology amplifiers. Customer will apply a system level calibration to the end equipment every day, canceling the error for both amplifiers and ADC. Does it help reduce the long term drift?

Thanks.

  • +1
    TI__Mastermind 47746 points

    Hi Jerry,

    Your assessment is correct. Below is a comparison between the two parts based on the data specification. 

    Customer will apply a system level calibration to the end equipment every day, canceling the error for both amplifiers and ADC. Does it help reduce the long term drift?

    If a customer is calibrated the measurement system daily, then the long term drift in the design are irrelevant. Daily calibration will calibrate out the most of the Offset related variables in a setup and/or a system. What remaining is the Vos drift over temperature. Typically, a precision measurement system is recommended to have a warmup period in a given environment. When a system's temperature is reached a thermal equilibrium, the system calibration is taken place. So the actual temperature change after a calibration is fairly small. 

    If you have additional questions, please let me know. 

    Best,

    Raymond