Buffer and line driver circuits are used in digital logic and communications systems to provide electrical isolation, impedance matching, and signal-level conversion between different logic families and transmission media. Buffers are primarily used for logic voltage level conversion between two different logic families. Line drivers are used to boost the logic waveform amplitude for long-distance transmission. Buffers act like current sources or sinks depending on the logic waveform level and can be used to drive multiple loads. Line drivers drive the long-distance line to its full voltage level capability, thus allowing it to transmit data over its specified maximum distance. Both buffers and line drivers have a very low output resistance, enabling them to drive multiple loads.