74HC139 Dual 2-Line to 4-Line Decoder Demultiplexer IC

The 74HC139 designed to decodes two binary weighted address inputs (nA0, nA1) to four mutually exclusive outputs (nY0 to nY3). Each decoder features an enable input (nE). When nE remains  HIGH all outputs forced HIGH. The enable input can be used as the data input for a 1-to-4 demultiplexer application. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC

The SN74HC139 is a high-performance memory decoding or data-routing device with extremely short propagation delay times. This decoder can reduce the consequences of system decoding in high-performance memory systems. When used with high-speed memories that use a quick enable circuit, the decoder’s delay time and the memory’s enable time are usually less than the memory’s typical access time. This indicates that the decoder’s effective system delay is negligible. In a single package, the SN74HC139 has two independent 2-line to 4-line decoders. As a result, in demultiplexing applications, the active-low enable (G) input is used as a data line. Meanwhile, each of the decoder/completely demultiplexer’s buffered inputs represents only one normalised load to its driving circuit.

A demultiplexer is a combinational logic circuit that switches a single common input line to one of numerous distinct output lines. The data distributor, often known as a Demultiplexer or “Demux,” is a device that distributes data. In a nutshell, this is the polar opposite of the Multiplexer from the last tutorial. The demultiplexer takes a single input data line and switches it one at a time to any of a number of distinct output lines. A serial data signal is fed into the demultiplexer, which converts it to parallel data on the output lines.