I'm working on a design based on MK10DN512VLQ10, the system has several ADC inputs, now we need to protect the inputs from 32V overvoltage. Since we don't want to modify the PCB(it was designed by someone else and the we need to keep up with the schedule), I thought a current limit resistor could solve the problem and limit the current under a safe range(5mA), and the voltage will be calmped by the diode inside MCU(judged from diagram in the datasheet like below).
So I use a 10K resistor to protect IO from 32V over voltage, when I appllied a 32V, the clamp voltage on the pin reachs 10V instead of around 4V. I also did minus and plus 10V sweep on the analog inputs(with 10K resistor), the behaviour is just like a 5V tolerance pin and only has negative voltage clamp ability.
Is it a 5V tolerance pin and where can I find the information about all 5V tolerance pins?
Does the MCU has 10V clamp for all 5V tolerance pins and what's the structure inside?