4 Digit 7-Segment Multiplexed Display

Multiplexed Display System:

Digital instruments such as frequency counters, function generators, and digital volumeters invariably have 7-segment displays to display their corresponding output values. Normally, each 7-segment display requires a separate BCD to seven-segment decoder driver in the non-multiplexed display system.

4 Digit 7-Segment Multiplexed Display:

The block diagram of a 4-digit multiplexed common cathode 7-segment display system is shown in the below figure:

Here, the dual 4-bit BCD inputs to be displayed in a multiplexed manner are connected to the inputs of four 4-to-1 multiplexers as 1A 1B 1C 1D(MSD), 2A 2B 2C 2D(second MSD), 3A 3B 3C 3D(third MSD), 4A 4B 4C 4D(fourth MSD). The select lines A and B of these multiplexer ICs are connected to the outputs of a 2-bit multiplexing counter, constructed using JK flip-flops. The output of the multiplexing counter also acts as the input for a 2 to 4 decoder IC 74155 whose outputs are digit select inputs (DS0 – DS3) of the 4-7 segment displays.