the cd4051 is an 8-channel analog multiplexer/demultiplexer with three address inputs (s1 to s3), an active low enable input (e), eight independent inputs/outputs (y0 to y7) and a common input/output (z). the device contains eight bidirectional analog switches, each with one side connected to an independent input/output (y0 to y7) and the other side connected to a common input/output (z). withe low, one of the eight switches is selected (low-impedance on-state) by s1 to s3. withe high, all switches are in the high-impedance off-state, independent of s1 to s3. if break before make is needed, then it is necessary to use the enable input.
vdd and vss are the supply voltage connections for the digital control inputs (s1 to s3, ande). the vdd to vss range is 3v to 9v. the analog inputs/outputs (y0 to y7, and z) can swing between vdd as a positive limit and vee as a negative limit. vdd-vee may not exceed 9v. unused inputs must be connected to vdd, vss, or another input. for operation as a digital multiplexer/demultiplexer, vee is connected to vss (typically ground). vee and vss are the supply voltage connections for the switches.