I try to measure the VDDA on an STM32F302R8 MCU using internal voltage reference (VREFINT) and it works fine and gives the correct results as long as the VDDA is above 3 V. Below 3V the value of the AD conversion of the VREFINT rapidly increase and at around 2.9 V it saturates and gives the value 4095. I haven't found any suggestions in the datasheet or in forums or somewhere else that it should not work below 3 V. Interestingly, measuring VREFINT gives a correct result (above 3 V of course) regardless of the state of the VREFEN bit. What do I miss?
