What does 'rail to rail' output operation really mean?

摘要

The advertisements for single-supply operational amplifiers often claim rail-to-rail output capability. What does this assertion really mean? Page one of a single-supply op amp's data sheet may call out "rail-to-rail input/output swing" in the title or bullets; read on, because if you are looking for a single-supply amplifier whose output can be driven all the way to one supply rail and/or the other, good luck. So, what should you know about an amplifier's performance that claims rail-to-rail output operation?