CD4051B — Single 8-Channel Analog Multiplexer / Demultiplexer

Overview

The CD4051B (and high-speed CMOS 74HC4051) is a single 8-channel analog multiplexer/demultiplexer IC manufactured by Texas Instruments, ON Semiconductor, NXP, and others. It acts as an 8-position digitally controlled solid-state rotary switch, connecting one of 8 independent channel inputs/outputs (CH0 to CH7) to a single common input/output pin (COM / COMMON IN/OUT).

Widely used to expand analog inputs on microcontrollers (such as reading 8 analog sensors through a single ADC pin on an ESP32 or Arduino), the CD4051 is bidirectional and can route both analog signals (up to 20V peak-to-peak with dual supplies) and digital signals without level conversion between channels.

Quick reference


Function	Single 8-Channel Analog Multiplexer / Demultiplexer (8:1 Mux)
Single Supply Voltage (`VDD` to `VSS`)	3.0 V to 20.0 V DC (CD4051B) / 2.0 V to 6.0 V (74HC4051)
Split Supply Range (`VDD` to `VEE`)	Up to 20.0 V peak-to-peak (e.g. `VDD` = +5V, `VEE` = -5V)
ON Resistance (`RON`)	80 Ω Typ (`VDD`-`VEE` = 15V) / 125 Ω Typ (`VDD`-`VEE` = 10V)
Control Inputs	3 Select lines (`A`, `B`, `C`) + 1 Inhibit (`INH`)
Bandwidth	20 MHz (-3 dB)
Packages	16-pin DIP, SOIC-16, TSSOP-16

Pin configuration

Pin (DIP-16)	Name	Type	Description
13, 14, 15, 12, 1, 5, 2, 4	`CH0`–`CH7`	Analog I/O	Independent channels 0 through 7 (`IN/OUT 0-7`)
3	`COM`	Analog I/O	Common channel terminal (`COMMON OUT/IN`)
6	`INH`	Input	Inhibit (Enable) control: High = all channels OFF; Low = selected channel ON
7	`VEE`	Power	Negative Analog Supply (connect to GND for single-supply 0-5V operation)
8	`VSS`	Power	Digital Ground (0V)
9	`C`	Input	Binary Select Address bit 2 (MSB)
10	`B`	Input	Binary Select Address bit 1
11	`A`	Input	Binary Select Address bit 0 (LSB)
16	`VDD`	Power	Positive Power Supply (+3V to +20V DC)

Functional description & truth table

The CD4051B features built-in level shifters between digital control inputs (A, B, C, INH) and internal bilateral transmission gates. This allows low-voltage digital control signals (e.g. 5V logic) to switch higher-voltage or negative-voltage analog signals (VEE down to -5V or -10V).

Channel Select Truth Table

Inhibit (`INH`)	Select `C`	Select `B`	Select `A`	Selected Channel Connected to `COM`
0	0	0	0	`CH0` (Pin 13)
0	0	0	1	`CH1` (Pin 14)
0	0	1	0	`CH2` (Pin 15)
0	0	1	1	`CH3` (Pin 12)
0	1	0	0	`CH4` (Pin 1)
0	1	0	1	`CH5` (Pin 5)
0	1	1	0	`CH6` (Pin 2)
0	1	1	1	`CH7` (Pin 4)
1	X	X	X	None (All channels isolated / High-Z)

Absolute maximum ratings

Warning

Stresses beyond these values cause permanent damage. Limits, not operating conditions.

Parameter	Rating	Unit
DC Supply Voltage (`VDD` - `VSS` or `VDD` - `VEE`)	-0.5 to +20.0	V
DC Input Voltage (`VIN`)	`VEE` - 0.5 to `VDD` + 0.5	V
Input Diode Current	±10	mA
Operating Temperature Range	-55 to +125	°C
Storage Temperature Range	-65 to +150	°C

Electrical characteristics

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Peak Switch ON Resistance	`RON`	—	125	240	Ω	`VDD` = 10V, `VEE` = 0V, `VIS` = `VEE` to `VDD`
Peak Switch ON Resistance	`RON`	—	80	160	Ω	`VDD` = 15V, `VEE` = 0V
Off Channel Leakage Current	`IOFF`	—	0.1	100	nA	`VDD` = 15V, `VEE` = 0V, `INH` = 5V
Propagation Delay (`A, B, C` to `COM`)	`tPHL` / `tPLH`	—	150	360	ns	`VDD` = 5V, `RL` = 10 kΩ, `CL` = 50 pF
Cut-off Frequency (-3 dB)	`fMAX`	—	20	—	MHz	`VDD` = 5V, `VEE` = -5V, `RL` = 1 kΩ

Typical application

text

       +5V DC VCC
           |
     +-----+-----+
     |           |
   100nF       10uF
     |           |
    GND         GND
     |           |
     +-----+-----+--------------+
           |                    |
        +--+--------------------+--+
        | 16                     3 |
        | VDD                  COM |---> MCU ADC Pin (A0)
        |                          |
        | 6 INH (GND)       CH0 13 |<--- Sensor 0 (Analog 0-5V)
        | 7 VEE (GND)       CH1 14 |<--- Sensor 1
        | 8 VSS (GND)       CH2 15 |<--- Sensor 2
        |                   CH3 12 |<--- Sensor 3
MCU GPIO-> 11 A             CH4  1 |<--- Sensor 4
MCU GPIO-> 10 B             CH5  5 |<--- Sensor 5
MCU GPIO->  9 C             CH6  2 |<--- Sensor 6
        |                   CH7  4 |<--- Sensor 7
        +---------------+----------+
                        |
                       GND

Common mistakes

Leaving VEE Unconnected in Single-Supply Systems: In standard single-supply 0-5V circuits, VEE (Pin 7) MUST be tied to GND (Pin 8). Leaving VEE floating will cause analog signals near 0V to be severely distorted or cut off.
Exceeding Supply Voltage Rails: The voltage of any analog signal passed through CHn or COM must stay strictly within VEE and VDD. Signals exceeding VDD or dropping below VEE will clamp through internal ESD diodes and distort other channels.
High Source Impedance Errors: RON (80–200 Ω) forms a voltage divider with downstream loads or ADC sampling capacitors. If reading high-impedance sensors, buffer the COM pin output with an op-amp voltage follower before feeding an MCU ADC.

Notes & further reading

74HC4051 Variant: The 74HC4051 is a high-speed 2V–6V CMOS version with much lower RON (~30 Ω at 4.5V) and faster switching times (< 20 ns), preferred for 3.3V/5V microcontroller digital and ADC multiplexing.
Related Multiplexers: CD4052 (Dual 4-channel multiplexer), CD4053 (Triple 2-channel multiplexer).

Interface	Parallel Select (A, B, C), INHIBIT, Common I/O (COM), 8 Analog Channels (CH0-CH7)
Package	16-pin DIP / SOIC-16 / TSSOP-16