What is the difference between CMOS logic IC multiplexers and bus switch multiplexers?

A CMOS logic IC multiplexer is a device that outputs a signal from one selected output terminal from multiple input signals. Since the output is CMOS structure, it has drive-ability and is not easily affected by the load in the later stage. The signals that can be handled are digital signals, and signal transmission is unidirectional (input → output). On the other hand, the bus switch multiplexer also outputs one signal from multiple input signals. It is easily affected by noise and is mainly used for signal blocking and switching. Both digital and analog signals can be handled. In addition, signals can be transmitted in both directions.

Fig. 1 CMOS logic IC Multiplexers（extract from TC74HC257 Data sheet）
Fig. 1 CMOS logic IC Multiplexers（extract from TC74HC257 Data sheet）

CMOS logic IC Multiplexers

A simple example is the TC74HC257 (4-circuit 2-channel multiplexer).
Select either the signal from the A terminal or the signal from the B terminal by the input signal level of the SELECT terminal, and output from the Y terminal.

Fig. 2 Bus switch multiplexers（extract fromTC7SB3157 data sheet）
Fig. 2 Bus switch multiplexers（extract fromTC7SB3157 data sheet）

Bus switch Multiplexers

TC7SB3157 (1-circuit 2-channel multiplexer) is used as an example.
Select the A-B1 route or A-B2 route with the input signal level of the S terminal (SELECT terminal). Signals can be transmitted in both directions.

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