ADS124S08: RTD Configuration

Hi Sarumathi,

Your approach 1 or 2 will work. Note that in both cases you need 2x measurements for the 3-wire RTD case (this is explained starting on pg. 17 in the RTD cookbook). In Approach 1, you could use 2x more channels to route IDACs to the bottom leg of the 3-wire RTD in order to use 2x IDACs for the 3-wire RTD measurement

Approach 3 and 4 will not work, as the current will split at the junction point on AIN0 if there are 2x RTDs connected at the same time. So you will not be able to correlate the RTD voltage to a temperature, since the current across each RTD will not be the same as the current across RREF (or some known multiple).

Approach 5 and 6 could work, but you would need at least another input channel connected to REFP0, as you would need this take measurements for the 2- and 3-wire RTDs (REFP0 is not a measurement channel)

Also, typically the 3-wire RTD measurement is taken between the top 2x leads. For example, in Approach 1, you would measure between AIN1/AIN2, not AIN2 and AIN3. This would be more important if you were going to use 2x IDACs for the 3-wire case.

-Bryan