How to connect 5V sensor to battery powered device?

[arraWX]

On the battery powered sensor build page it is suggested to power 5V sensors using a step up converter. I guess that most 5V sensors use 5V logic levels for their digital output. Furthermore, as far as I understand the ATmega328P digital inputs do not accept voltages higher than Vcc + 0.5V (see datasheet p. 299). Consider as an example a sensebender operating at low battery level, say 2V. Wouldn’t the sensebender be harmed by a 5V digital signal from an attached sensor?

I hope someone in here can help explain how to properly connect a 5V sensor to battery powered device.

[AWI]

@arraWX use a 'level converter' or find a 3v alternative for the sensor?

[arraWX]

Thanks @AWI! A level converter is exactely what is needed.