Analogue input when changing Vref

Hi,
I wanted to know if there would be a problem with having an input with a higher voltage than the Vref (ie 3.3v) in the analogue inputs as long as it is lower than 5 volts.
I need to read an analogue sensor which can give any value from 0 to 5 but i only care for the range that is lower than 3volts, so in order to have a higher accuracy i wanted to put the vref of 3.3 so my values go 0 to 1024 in only 3.3 volts, but my sensor will still give me some values between 3.3 and 5.5 volts which i dont care if i read as 1024. My question is will i damage the arduino if i do this? ( i might also use the internal 1.1v as reference)

Thanks for your replies

There's no problem with having a voltage higher than Vref, just as long as it isn't more than half a volt higher than the supply.

Why are you posting here?

Thanks. Sorry, i guess i didn't find a better section for it. :~

cristo829:
Hi,
I wanted to know if there would be a problem with having an input with a higher voltage than the Vref (ie 3.3v) in the analogue inputs as long as it is lower than 5 volts.
I need to read an analogue sensor which can give any value from 0 to 5 but i only care for the range that is lower than 3volts, so in order to have a higher accuracy i wanted to put the vref of 3.3 so my values go 0 to 1024 in only 3.3 volts, but my sensor will still give me some values between 3.3 and 5.5 volts which i dont care if i read as 1024. My question is will i damage the arduino if i do this? ( i might also use the internal 1.1v as reference)

Thanks for your replies

It's more a question of what Vcc the AVR chip is operating at if pin damage is possible. 5vdc applied to any pin (except reset pin) if the chip's Vcc is running at 3.3vdc can cause pin damage. Any applied voltage above whatever voltage reference the ADC is using but below what the chip's Vcc is using is not damaging, it just will return 1023 counts for any value at or above the voltage reference being used.

Thanks, i think you solved all my doubts XD