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Post: Hello Christophe The voltage reference used on the Expander Pi can only supply 2mA so it would not be suitable for powering your thermistors. You could use an external reference such as the [url=https://www.microchip.com/en-us/product/MCP1501]MCP1501[/url] from Microchip which can supply up to 20mA. The MCP1501 includes a shutdown pin which you could use to turn the reference off when you are not measuring which would reduce the heating problem. According to the [url=https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP1501-Data-Sheet-DS20005474.pdf]datasheet for the MCP1501[/url] on page 11, the reference takes about 700µS to stabilise so you will need to add a delay between switching the reference on and taking a sample from the ADC. I have updated the ADC class in the Expander Pi library to use a 200KHz SPI bus so it should be more precise now.