CD4066 — Quad Bilateral Analog Switch

Overview

The CD4066 (CD4066B / HEF4066B) is a quad bilateral analog switch IC manufactured by Texas Instruments, ON Semiconductor, and Renesas. It contains four independent digitally-controlled single-pole single-throw (SPST) analog switches inside a 14-pin package.

Each bilateral switch handles signal peak-to-peak swings up to 18.0V DC (when $VDD = 18\text{V}$ ) with a low on-state resistance ( $R_{ON} = 80\ \Omega$ typical). Signals travel in either direction with minimal distortion, making the CD4066 widely used in audio muting circuits, programmable filter switching, sample-and-hold circuits, and digital signal gating.

Quick reference


Supply Voltage (`VDD - VSS`)	3.0 V to 18.0 V DC (CD4000B) / 2.0V to 6.0V DC (74HC4066)
Switches	4 Independent SPST Bilateral Switches ( $A, B, C, D$ )
Control Signal Level	Active-HIGH (High = Switch CLOSED/ON; Low = Switch OPEN/OFF)
On-Resistance ( $R_{ON}$ )	$80\ \Omega$ typical at $VDD = 15\text{V}$ ( $125\ \Omega$ at $10\text{V}$ )
Bandwidth	$40\text{ MHz}$ (-3 dB cutoff frequency)
Off-State Leakage Current	$\pm 10\text{ pA}$ typical
Package	14-pin DIP / SOIC-14 / TSSOP-14

Pinout (DIP-14 Package)

text

             ┌───┴───┐
    IN/OUT A 1│ 1   14│ VDD (+3V to +18V)
    OUT/IN A 2│       │13 CONTROL A
    OUT/IN B 3│ CD4066│12 CONTROL D
    IN/OUT B 4│       │11 IN/OUT D
   CONTROL B 5│       │10 OUT/IN D
   CONTROL C 6│       │9  OUT/IN C
    VSS (GND)7│       │8  IN/OUT C
             └───────┘

Pin	Name	Description
1	`IN/OUT A`	Switch A Input/Output Terminal
2	`OUT/IN A`	Switch A Output/Input Terminal
3	`OUT/IN B`	Switch B Output/Input Terminal
4	`IN/OUT B`	Switch B Input/Output Terminal
5	`CONTROL B`	Switch B Digital Control Input (Active-HIGH)
6	`CONTROL C`	Switch C Digital Control Input (Active-HIGH)
7	`VSS`	Digital Ground (0 V)
8	`IN/OUT C`	Switch C Input/Output Terminal
9	`OUT/IN C`	Switch C Output/Input Terminal
10	`OUT/IN D`	Switch D Output/Input Terminal
11	`IN/OUT D`	Switch D Input/Output Terminal
12	`CONTROL D`	Switch D Digital Control Input (Active-HIGH)
13	`CONTROL A`	Switch A Digital Control Input (Active-HIGH)
14	`VDD`	Positive Power Supply (+3.0V to +18.0V DC)

Function Table (Per Switch)

Control Input	Switch State	Signal Path State
High ( $1$ )	Closed (ON)	Low Resistance ( $R_{ON} \approx 80\ \Omega$ )
Low ( $0$ )	Open (OFF)	High Impedance (High-Z Off, $> 100\text{ M}\Omega$ )

Common mistakes

Leaving unused control inputs floating: Unused control pins (CONTROL A/B/C/D) must be pulled LOW to GND or HIGH to VDD. Floating control inputs cause erratic switch behavior and excessive supply current.
Forgetting that $R_{ON}$ varies with signal voltage: $R_{ON}$ fluctuates slightly as the signal voltage approaches $VDD / 2$ . In precision analog circuits requiring flat $R_{ON}$ , use modern precision analog switches like the DG419 or ADG701.

Notes

CD4066 vs CD4016: CD4066 is the upgraded version of CD4016 with much lower $R_{ON}$ ( $80\ \Omega$ vs $300\ \Omega$ ) and constant $R_{ON}$ across the entire input voltage range.