Using 2.5V precision reference to Aref pin, from INA125 [Solved]


I have a question on using A-ref pin. If I take 2.5V precision reference from INA125 and connect it to A-ref pin, what should be the maximum analog input voltage to an Analog input pin? Can the range still be 0-5V? Or should it be 0-2.5V?

Homework : I read analogreference tutorial pages on, I can understand how it will change resolution but I am unable to find out the maximum voltage to analog pin - if 2.5V precision reference is used for A-ref. Thanks for your replies.

Specifications : Arduino Uno R3, Arduino 1.0 IDE, Ubuntu GNU/Linux 12.04.

You can still hook 5V to an input, but any voltage above the reference will read back as 1023.

Thank you, now I understand that, I was worried applying more than 2.5 may cause damage. :roll_eyes:

From datasheet of INA125, The precision voltage reference from INA125 has 0.25% error. So will it be safe if I take 5V precision reference and connect it to A-ref, I mean to ask, if the excess error will damage the ADC of Arduino Uno or no?

I think (and you can check in the datasheet) that the voltage on [u]any[/u] pin should not exceed the supply voltage by more than 0.5V, nor be lower than 0.5V below ground.

Thank you.