Hello, I'm surprised I couldn't find this question already on the board. My apologies if I missed it : What happens when an analog input gets a tension that is outside range ? I have a circuit that has a -9V/+9V range and I want to plug it on the arduino. Will it damage it ? I do not really care about getting exact measurements of the extreme values as I am seldom interested in the frequency of the signal and in its lower values.
I failed to find any reference on this. I know that a negative tension will not be correctly measured, but will it damage the board ? Aren't there inner protections preventing damage ?
From the data sheet of the ATmegs chip (and virtually every other chip in the universe):-
28.1 Absolute Maximum Ratings
Voltage on any Pin except RESET
with respect to Ground ................................-0.5V to VCC+0.5V
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage
to the device. This is a stress rating only and
functional operation of the device at these or
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
I was aware that the ATmel would probably not like it, but I wondered if maybe the board had some builtin protections.
But I just looked at the board and... heh, it is simpler than I thought. The analog IN goes directly to the chip's pin. I feel a bit stupid now >_<. Thanks for the link anyway. And damnit for not anticipating it. I'll have to go in the big scary outworld to hunt down wild diodes.