Any harm in using 5v on Aref on a 3v3 board?

Other Hardware Sensors
1

I need to use a 5v sensor with a atmega328 running 3v3. The sensor's output is 0.5v to 4.5v so I'll need to use an analog pin. I'm also using an xbee and would like to keep the board 3v3 to make things easier.

My question is, If the atmega can run at 5v, is the any harm in putting more than vcc into the analog pin / ARef pin?

Thanks guys for your help.

2

Signals should not exceed Vcc +0.5V. If they do, you risk damaging the input clamp diodes.
Use a resistor divided to keep your signal level to <=3.3V.
Is it a digital signal, just high & low?

3

analog signal ranging from .5v to 4.5v.

Thanks, Glad I asked before doing it!