Fei, I'm glad that you were able to get it to work. I'm a little surprised that the problem was that the AVDD was a little lower than expected. How low was the value? There are some small differences in operation with different AVDD. This includes the noise (which is shown in Tables 1-6), the PSR, which is explained in the Electrical Characteristics table, and power supply current shown in the Typical Characteristics curves. All of these are relatively minor effects and I don't think it should significantly affect your performance. I would note that with a low analog supply, you need to be careful on selecting your RTD, reference resistor, and the excitation current. The compliance voltage for the excitation current only goes to AVDD-0.7V. If there is no RTD sensor in the connector, it is likely that the AINP will be pulled up by the excitation current source, and the AINN will be pulled low from the lack of current going to the reference resistor. In this case, I would expect that the ADC would over range and give you a full scale reading of 7FFFFF. If you need any other evidence, you can use the system monitor and use the internal reference to read the external reference value (either pins to REF0 or REF1). If the reference reads 0, the excitation current isn't going through the RTD to the reference resistor. Joseph Wu
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