The Arduino Uno Rev3 has an OpAmp (TI LMV358IDGKR datasheet) where the non-inverting input ("CMP") is connected via a voltage divider to Vin. The OpAmp's supply is connected to 5V.
On the Arduino Uno Rev3 product page (click) they specify the recommended and limit ratings for the boards input voltage:
Looking at the LMV358IDGKR absolute maximum ratings i am wondering why having (in the case of say input voltage > 11.4V) a voltage above 5.7V at the OpAmp's input ("CMP") isn't a problem? For my understanding the OpAmp will blow up at say 15V input voltage?!
(Well voltage at barrel jack might be ok up to roughly 12.5V because there is a diode between power jack and VIN, but above?)
Best Answer
The "input" in question is the power supply voltage. That Arduino uses an SPX1117 regulator.
Other considerations are thermal (on the high end) and the typical vs. worst-case dropout voltage of the regulator (on the low end).
Not important to this question, but for those using clones, note that the popular AMS1117 has a lower rated absolute maximum input voltage (15V).
As far as your op-amp circuit the Absolute Maximum input voltage to the divider would be 11.4V. The LMV358 is a bipolar technology part and does not have diodes from inputs to Vcc, so care is called for. You can add a diode if you need to.