I use an Arduino Due which is rated 3.3V as a kind of waveform oscilloscope to display signals on my PC. As I knew I had to scale my signals to 3.3V to avoid damaging the analog pins.
Here is the warning on the Arduino Due specifications page:
Warning: Unlike most Arduino boards, the Arduino Due board runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Applying voltages higher than 3.3V to any I/O pin could damage the board.
Some time ago I used a voltage divider to do this but lately not sure for what reason I used just a 20k resistor.
The Arduino Due analog pin seems fine, I have used it to measure 4.5V (as measured by the multimeter) for quite some time, so can someone clarify to me why the pin or the board is not damaged, what difference makes a voltage with very small current ( 0.265mA in this case ). Does the voltage measured by the ADC on the Due reach the microcontroller? (I suppose yes as the ADC is part of it)