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ADS1015-Q1 Gain error and Gain drift

Takao Yamamoto
Genius 4135 points

Dear all,

This device has low INL=1LSB.

But I feel that this Gain error and Gain drift is big.

Gain error: 0.25%(MAX)→This is equal to 10 LSB because of 12 bit ADC.

Gain drift: 40ppm/℃(MAX)→This become to 0.4% at changing 100℃. This is equal to 16.4 LSB.

In this bad situation, the significant bit become 7~8 bit because of 26 total bit.

Is this device premised on correcting Gain error / Gain drift?

Best regards,

  • 0
    TI__Genius 16410 points
    Hello Yamamoto-san,

    The appropriate application engineer has been notified, and will respond accordingly.

    Regards,
    Karl
  • 0
    TI__Mastermind 23810 points
    Takao,
    The gain error is usually calibrated out since a two point calibration is all you need. If the accuracy is not enough with this, then the gain drift can be calibrated as well. If you know the temperature range the device will be used at, you can take an additional calibration measurement across temperature.
    Also note that the typical gain drift ratings for this device are only around 5 ppm/C. Almost all parts will operate in this region. I might be able to dig up some of the calibration data if you would be interested in the actual gain drift test results for this device.
  • 0 in reply to Clancy Soehren
    Genius 4135 points

    Dear Clancy,

    Thank you for your reply.

    I would like to know additionally.

    You said 'Almost all parts will operate in this region'.

    I thought that this means 'Sometimes, there are products having 40 ppm/C'.

    Is it possible to except 40 ppm/C products?

    Or, is it possible to reduce the error to 35 ppm/C?

    Best regards,

  • 0 in reply to Takao Yamamoto
    TI__Mastermind 23810 points
    Takao,
    The characterization data for gain error drift shows that for 30 units the maximum gain error is less than 10ppm/C. However, we have to put a maximum number several standard deviations away so that we can ensure that the spec is valid.
    One of the advantages of a delta-sigma converter is repeatibility and not accuracy unless calibration is performed. Also, you can look at more accurate parts if that's a key system requirement. Let me know if you would like some recommendations.
    Thanks,-Clancy