LTC2983 getting voltage or resistance results

Hi mfasano, 

     As it is not the primary use of the part, we did not document in the datasheet. The generated C code contains enough information to get the results if you'd like. Additionally it documents the format. 

    For voltage there is also the direct ADC measurement method which is documented in the datasheet. 

    Let me know if you have any issues using these raw results. 

-Logan

Hi mfasano, 

     As it is not the primary use of the part, we did not document in the datasheet. The generated C code contains enough information to get the results if you'd like. Additionally it documents the format. 

    For voltage there is also the direct ADC measurement method which is documented in the datasheet. 

    Let me know if you have any issues using these raw results. 

-Logan

Is there an accuracy specification applicable for the voltage measurements?  

Do the Thermocouple Error charts on page 6 of the datasheet reflect measurement errors for the system as a whole for a typical sample of the thermocouple sensors listed or is it showing a subset of the components contributing to measurement error tolerances?

Wondering if those charts are based on a voltage accuracy of approximately +/- 1µV. 

Can the accuracy limit estimations be determined for operation over a full temperature range of -40 to 85 deg C for the I-grade part?

You can use the ADC and reference specifications in the datasheet to calculate voltage accuracy - the voltage reference tempco, scaled relative to your input percentage of Vref, will dominate the error. 

You'll need to look at ADC offset, INL, positive and negative full scale error and error drift (these are effectively a gain error and can be scaled if your input is less than full scale) - as well as reference tempco, again scaled.

Hope this helps. In many cases the thermocouple accuracy can be considered a superset of the ADC voltage accuracy as it contains small mathematical errors due to the conversion from mV to temp including cold junction compensation. 

If you haven't seen it already, the latest versions of the GUI tool include an error estimator tool which may be of some help. It's accessed by the "edit" button when configuring a sensor.

-Logan