4 Points Used by the Analog Switch CD4051

1. When using a single power supply, the VEE of the CD4051 can be connected to GND.

2. It is strongly recommended to add pull resistors to the A, B, and C three-chip select terminals.

3. Do not add filter capacitors (parallel to ground) on the common output of CD4051. Otherwise, the voltage after conversion of different channels will cause great error after being discharged by capacitor.

4. When the output terminal (INH) is disabled, all outputs are cut off, so this terminal is grounded when applied. When switching audio signals, it is best to connect a DC blocking capacitor to the input and output terminals.

IO port expansion using CD4051 analog switch chip

1, CD4051 introduction

For details reference: TI CD4051 Datasheet

It can be understood as a single-pole 8-throw switch, the principle is as follows:

CD4051 analog switch chip realizes IO port expansion

Use three IOs to control the A, B, and C address pins to connect the 3 pins to the 8 pins. The truth table is as follows:

CD4051 analog switch chip realizes IO port expansion

2, typical application schematic

CD4051 analog switch chip realizes IO port expansion

By connecting the circuit in this way, it is possible to expand the four IO ports to eight, and realize the input and output functions. But they can't work at the same time, they can