ADS131M06: Offset error and offset drift when using an "ideal" external 1.25 V reference

James Dupre

Part Number: ADS131M06

Tool/software:

Hi,

If I use an "ideal" external 1.25 V reference for the vref input of the ADS131M06 *and* all the negative inputs for all 6 channels, does this largely cancel out any effects caused by offset error and offset drift? In other words, are offset error and drift common mode and identically applicable to the positive and negative inputs of each channel? An "ideal" 1.25 V reference in this context means that it has 0 source impedance, is precisely 1.25 V, and does not vary in response to changes in temperature or input voltage.

Regards,
James

4 months ago

0 Dale Li 4 months ago

TI__Mastermind 45705 points

Hi James,

The offset error refers to the deviation of the ADC's actual transfer function from the ideal one, specifically at the zero-crossing point, it is caused by non-ideal effects like a mismatch between internal components. You can watch the video for the details: TI Precision Labs-ADC - AC & DC specifications: Offset error, gain error, CMRR, PSRR, SNR and THD.

Your approach does not help on minimizing the offset error. You can calibrate out the offset error by using the offset calibration register on ADS131M06 or doing the calibration in your software in your microcontroller. Check the details in ADS131M06 datasheet.

-Dale

0 James Dupre 3 months ago in reply to Dale Li

Prodigy 120 points

Thanks for your detailed response, Dale.

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ADS131M06: Offset error and offset drift when using an "ideal" external 1.25 V reference