max voltage

Hi everyone!
Can someone tell me what maximum voltage I can send into arduino Uno without damaging it ?
Thanks for your answers.

Usually the processor supply voltage, plus a half volt.

Check the datasheet

If you're talking about powering the UNO see Arduino Uno Rev3 — Arduino Official Store and look under Documentation.


In a I/O pin, or into the UNO power port?

The first, Vcc to Vcc + 0.5V

The power port, approximate maximum is 12V as there is a regulator on board to produce 5V for the processor. 7V is the lowest. Depending on the current draw from the UNO +5V pin up to 12V perhaps a little more. Again, depends on the draw from the +5V pin. The regulator is based on watts. There more current available at 7V than there is at 12V.

Thanks for the DATASHEET,

Sorry , I forgot to mention that I want to know the max voltage that the card can stand in the analogic port (like A0)

I forgot to mention that I want to know the max voltage that the card can stand in the analogic port (like A0)

Then it is 0.6V above the Vcc power rail. Anything over the Vcc voltage will read 1023.

I use this program,
I have a barrier which sends 0V to 10V and I want to measure its Voltage with the Arduino UNO. But the measure doesn't really work.
Is something wrong with the program ? or is it the Arduino ?

// Fonction setup(),
void setup() {


// Fonction loop(),
void loop() {

int valeur = analogRead(A0);

float tension = valeur * (5.0 / 1023.0);


You have a divide-by-two on the 10V input, right?

I think I misspoke. I meant the barrier’s maximum voltage is 10V.

Did you actually understand reply#5?
You can’t put more than 0.6V into an analogue pin than the supply voltage of the Arduino’s Vcc which in itself has a maximum voltage of 5.6V.
So putting anything over 5V into an analogue pin will screw up your Arduino, and anything over 5V, the Vref voltage by default will not give increasing readings.

Vcc is NOT the voltage you put into the power jack, that is regulated down to 5V to provide the Vcc for the Arduino’s chip.

Thanks for reply , I have find a solution with a brigde divisor and the Arduino can read all that I need.

Good that you have it working.

brigde divisor

Is not the right name, it is called a potential divider.

Can you post a circuit diagram of your project please?
This may be of help to others enquiring about a similar situation.

Thanks.. Tom.. :slight_smile: