Hi…i am a new user here. As per my knowledge the ADC input model shows ESD clamp diodes. No abs max current rating for them. A guess would be 20mA like the processors which have similar ADCs built in. A resistor in series with the input will limit clamp diode current while adding some conversion error dependant on supply voltage and clock speed. Limiting the clamp diode current would be working on the assumption the clamp diodes do have some current rating.