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ADS1256: offset error in detail

Part Number: ADS1256

Dear Specialists,

My customer'd  like to acquire offset error data in detail.

I would be grateful if you could advise.

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Regarding offset error,

"On the level of the noise" is written on ELECTRICAL CHARACTERISTICS of the DATA SHEET.

In this case, how much are actual values?

In addition, could you provide the offset data without calibration.

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I appreciate your great help in advance.

Best regards,

Shinichi

  • Hi Shinichi-san,

    I looked at our characterization data for the ADS1256 and I didn't seem much with respect to offset. The expectation is that the customer will enable the Auto-Calibration feature in the ADS1256 in order to reduce the offset to the level of the noise. Then the ADC is only really subject to the offset drift. Is the customer not able to use the auto-calibration feature?

    The offset cannot be reduced to below the level of the ADC noise because the ADC cannot resolve a signal that is lower than the ADC noise. So when the customer enables the Auto-Calibration feature, the offset is reduced such that it is equal to the ADC noise at that data rate, gain setting, and buffer selection. The noise is specified in Table 1 (buffer on) and Table 4 (buffer off) in the ADS1256 datasheet. You can use the values in these tables as the offset values after calibration

    -Bryan

  • Hi Bryan,

    Thank you for your reply.

    I'll share your information with the customer.

    At this time, I don't know the customer use auto-calibration.

    When I obtain, I'll feedback to you. 

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • You are welcome, Shinichi-san.

    Let us know if anything else is needed from the customer

    -Bryan

  • Hi Bryan,

    Thank you for your reply.

    I confirmed the customer.

    They didn't use auto calibration.

    In this case, the offset error is not specified and could not determine OK or NG.

    So they'll conduct auto calibration and confirm the data. 

    When the offset error is out of spec they measured, I consult you again.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • Thanks for the update, Shinichi-san.

    -Bryan