The 74HC4851; 74HCT4851 are high-speed Si-gate CMOS devices and are specified in compliance with JEDEC standard no. 7A.

The 74HC4851; 74HCT4851 are 8-channel analog multiplexers/demultiplexers with three digital select inputs (S0 to S2), an active-LOW enable input (E), eight independent inputs/outputs (Y0 to Y7) and a common input/output (Z). The devices feature injection-current effect control, which has excellent value in automotive applications where voltages in excess of the supply voltage are common.

With E LOW, one of the eight switches is selected (low impedance ON-state) by S0 to S2. With E HIGH, all switches are in the high-impedance OFF-state, independent of S0 to S2.

The injection-current effect control allows signals at disabled analog input channels to exceed the supply voltage without affecting the signal of the enabled analog channel. This eliminates the need for external diode/resistor networks typically used to keep the analog channel signals within the supply-voltage range.