ADS1231: About the maximum value for the offset error and drift.

Hi Kengo,

The ADS1231 unfortunately does not have a guaranteed min/max specification for offset and offset drift.  Generally the ADS1231 is used for bridge type measurements where any sensor offset is subtracted from the conversion output which would also include the offset of the ADS1231 PGA to establish a 0, or no load, result.

For the ADS1231, I did review the characterization data and I can say that for the bulk of devices tested the distribution was very tight relative to the typical initial offset and the drift trend that is shown in the ADS1231 datasheet in Figure 7 on page 8 (which is a normalized graph set to room temperature).  However there is no guaranteed performance for the ADS1231.

As there are a number of devices in the portfolio, one method of differentiating devices is by price.  One way we can reduce the cost of build is by reducing the test time by lowering the number of guaranteed specifications.  That is why only a typical value is shown based on characterization. 

Another way of reducing cost is by limiting the available features.  The ADS1231 does not have a built-in offset calibration to remove device offset.  If offset maximum values are required, then I would suggest using the ADS1232.  The ADS1232 does have guaranteed specifications for initial offset error.  However the drift characteristics for the ADS1232 are limited to typical specifications, but as the ADS1232 does have offset calibration features the offset can be removed by issuing periodic offset calibrations.

Best regards,

Bob B