We want to use the SDADC to measure the temperature of a PT100 sensor. The measurement should have a very high accuracy of +-0.5Kelvin. Therefore, it is important to have a low offset error. The datasheet lists very large values for single-ended mode, e.g., 2000uV for VREFSD+=3.3.
Differential mode cannot be used because the number of channels would then be insufficient (We need 18 channels, and the STM32F3 has only 11 differential Channels).
There is a product lineup where the offset error is specified as < 1 LSB.
Why is the offset error specified in the datasheet so high in single-ended mode ?
Can it be reduced by using a buffer op-amp at the input ( The buffer op-amp would mean a very low source impedance and would reduce e.g. bias errors ) ?
I have also read the AN4207 section offset calibration, but there are no details about single ended or differential ended offset errors after calibration
