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ADS1231: Zero drift calculation

Nikhil F
Prodigy 110 points

Part Number: ADS1231

Tool/software:

Hello,

We are using ADS1231 in our product.

We are unable to find Zero drift parameter in datasheet of ASD1231. Please help for it.

If any related application note for Zero drift calculations is available please share so that I can make calculation with reference to it.

Nikhil

  • 0
    TI__Mastermind 49300 points

    Hello Nikhil,

    I assume you are looking for temperature drift data for the ADS1231.  This can be found in the datasheet under Input offset drift and Gain drift.

    As an example, assuming you calibrate at 25C and then the system temperature is increased to 60C, this will be a 35C increase.  The change in offset voltage sill be 35C*20nV/C=0.7uV and the gain error change will be 35C*2ppm/C=70ppm, or 0.007%.

    Application note 'A Basic Guide to Bridge Measurements' discusses these different error sources and how they effect system measurement accuracy.

    https://www.ti.com/lit/an/sbaa532a/sbaa532a.pdf

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0
    Prodigy 110 points

    Hi Keith,

    You mean calculation of change in offset voltage as you derived is same as calculations for zero drift?

    We want to calculate zero drift parameter of ADC .

    And in derived gain error calculations it is 0.007% or 0.07% should be there?

    Regards

    Nikhil

  • 0 in reply to Nikhil F
    TI__Mastermind 49300 points

    Hello Nikhil,

    Normally 'zero-drift' refers to changes in offset voltage over temperature, but can also apply to changes in gain as well.  Clearly, these errors should be as close to 0 as possible, but there will still be some drift in specifications that occurs.

    The above examples I provided are for a temperature change from room temperature (25C) up to 60C, or a total temperature change of 35C.  You can adjust these calculations based on the temperature range that you intend to support for your product. 

    Worst case, the ADC is specified from -40C up to 85C.  Assuming you calibrate at 25C, then the maximum change in temperature will be from 25C to -40C, or 65C delta.  In this case, you can expect the offset voltage to change by 1.3uV and the gain to change by 0.013%.

    Regards,
    Keith