4051

The 4051 is a CMOS analog multiplexer/demultiplexer integrated circuit in the 4000-series family. It provides eight single-pole, bilateral switches between eight input/output pins labeled Y1 through Y8 and a common I/O pin Z. The switches are controlled by three select inputs S1, S2, and S3 and an inhibit input INH. When a channel is selected, the corresponding switch closes, connecting YN to Z; the other Y pins are isolated. The INH input, when asserted, disables all switches regardless of the select lines. The device is bidirectional, allowing signals to pass between Z and any chosen Y pin in either direction.

It operates on a supply voltage typically ranging from about 3 to 18 volts and is designed to pass analog signals within the supply range. The conduction path on the selected channel has a relatively low on-resistance, while non-selected channels present high impedance, minimizing leakage. Leakage currents and on-resistance vary with supply voltage and temperature.

Typical applications include multiplexing signals from multiple sensors to a single analog-to-digital converter, or distributing a single source to multiple destinations in instrumentation, data acquisition, audio, and control systems. The 4051 is widely used in both hobbyist and professional electronics and has many manufacturers producing compatible variants (for example CD4051B). It is one of the standard 4000-series analog multiplexers/demultiplexers, noted for its wide operating voltage range and relatively simple control scheme.