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INA190-Q1: Error Calculation

Shinichi Yokota
Genius 9715 points
Part Number: INA190-Q1
Other Parts Discussed in Thread: INA240-Q1

Hello,

I have a few questions about INA190-Q1's error calculation.

  • Does the gain error include nonlinearity error? Or do I need to consider the nonlinearity error separately?
  • What's the Max value of the nonlinearity error over a full temperature range (TA = -40 to 125 °C)?
  • Can Table 2 (Total Error Calculation) on page 20 of INA240-Q1's data sheet be used for the INA190-Q1, too?

Best regards,
Shinichi Yokota

  • 0
    TI__Mastermind 31735 points

    Hello Shinichi,

    The gain error does not include nonlinearity error. These specifications are already independent.

    We do not have data/specifications for nonlinearity over temperature.

    Table 2 of INA240-Q1 datasheet can be used to calculate RSS error for INA190-Q1; however, this calculation does not include offset contribution from temperature (Vos_drift) nor PSR (Vos_PSR) nor offset error from input bias currents (Vos_IB), which may be relevant depending on the application.

    For a complete error equations you can refer to the circuit application note: https://www.ti.com/lit/an/sboa336/sboa336.pdf

    In this document, the total absolute error is calculated and not the root-sum-squared (RSS) error. Also, linearity is not included as it is negligible to other errors.

    For more information about gain error, linearity error, and calibration please view our very recent training video here:

    https://training.ti.com/ti-precision-labs-current-sense-amplifiers-gain-error?context=1139747-1139745-1138708-1139852-1140045

    Hope this helps.

    Best,

    Peter

  • 0 in reply to Peter Iliya
    TI__Genius 9715 points

    Peter,

    Peter Iliya said:

    We do not have data/specifications for nonlinearity over temperature.

    Could you provide me with a rough estimate on the Max value if it's OK to me? Without anything, I cannot see if it's negligible against other error components. Is it OK to consider the Typ value on the data sheet almost equal to the stddev of the error distribution?

    Peter Iliya said:

    For more information about gain error, linearity error, and calibration please view our very recent training video here:

    Do you know if the Japanese transcription is available on this video? I cannot find it on the Japanese site of TI.com

    Best regards,
    Shinichi Yokota

  • 0 in reply to Shinichi Yokota
    TI__Mastermind 31735 points

    Hey Shinichi,

    I do not have a rough estimate, but I am pretty sure the shift in linearity over temperature is insignificant. I am asking around for any information on this, but overall nonlinearity error will always be dominated by gain error.

    The typical value is not a representation of the stdev of error distribution. They typical spec value is usually the center of the error distribution.

    I do not think there is a Japanese transcription for the video available currently, but the key slide are graphical with equations, so they may be intuitive for the time being.

    Hope this helps. 

    Peter