Fundamental Digital Electronics/Digital DeMultiplexing

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Digital demultiplexers[edit]

Demultiplexers take one data input and a number of selection inputs, and they have several outputs. They forward the data input to one of the outputs depending on the values of the selection inputs. Demultiplexers are sometimes convenient for designing general purpose logic, because if the demultiplexer's input is always true, the demultiplexer acts as a decoder. This means that any function of the selection bits can be constructed by logically OR-ing the correct set of outputs.

Example: A Single Bit 1-to-4 Line Demultiplexer

List of ICs which provide demultiplexing[edit]

The 7400 series has several ICs that contain demultiplexer(s):

S.No. IC No. Function Output State
1 74139 Dual 1:4 demux. Output is inverted input
3 74156 Dual 1:4 demux. Output is open collector
4 74138 1:8 demux. Output is inverted input
5 74154 1:16 demux. Output is inverted input
6 74159 1:16 demux. Output is open collector and same as input

References[edit]

Multiplexer