I'm trying to measure the voltage using a voltage sensor. If the power source is activated, the sensor outputs 2.6V, and if deactivated it outputs around 20mV.
However, If I connect the signal pin to the ADC pin on the Raspberry Pi Pico, the output voltage of the sensor drops to ~50mV. Thus, I can't measure anything because the ADC pin always outputs the same value.
This voltage drop does not happen if I connect the signal pin on the sensor to any other GPIO pin on the Pico.
Is this normal behaviour or are my ADC pins broken?