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STM32 differential ADC in pseudodifferential mode

Question asked by Uwe Bonnes on Oct 30, 2017



F3, L4 and H7 ADCs allow differential measurements. While the F3 datasheets does not state any range for the common mode input voltage, L4 and H7 allow only a range of +/- 10 % around Vref/2 as common mode voltage.


A pseudo-differential measurement, sensing some remote signal _and_ remote ground at some milli Volt offset to system ground is outside the allowed range most of the time.


What is to be expected for the L4/H7 ADC in a situation when common mode input voltage is far of the allowed range but otherwise inside input voltage and measurement range?