Logic level

In digital circuits, a logic level is one of a finite number of states that a signal can have. Logic levels are usually represented by the voltage difference between the signal and ground (or some other common reference point), although other standards exist. The range of voltage levels that represents each state depends on the Logic family being used.

In binary logic the two levels are logical high and logical low, which generally correspond to a binary 1 and 0 respectively. Signals with one of these two levels can be used in boolean logic for digital circuit design or analysis.

In three-state logic, an output device can also be high impedance. This is not a logic level, but means that the output is not controlling the state of the connected circuit.

=Reference=


 * http://en.wikipedia.org/wiki/Logic_level