Details of internal pin circuitry?

[Scooter Dawkins]

What are the details of internal pin connection circuitry when connected as GPIO/IRQ vs ADC vs Comparator? Is there an internal pull down (what value)? Is there internal diode? ESD protection circuitry details? For example, I see different effects on my input signal when configured as IRQ with No Pull vs ADC.

[ketiljo]

Please refer to the GPIO pin details figure in the product specification.

The pin is connected directly to the ADC input mux when this is enabled, any pull resistors are then disconnected. 

ESD protection is always enabled. This mainly consists of diodes to VCC and GND.

[Scooter Dawkins]

Could you provide details of the diode type and characteristics?

[ketiljo]

It's a shottky diode. Hence the requirement to keep the voltage on a pin to max VDD + 0.3 V. Above this, the diode will start to conduct.