CD4081B — Quad 2-Input AND Gate

Overview

The CD4081B (CD4081) is a monolithic CMOS integrated circuit containing four independent 2-input AND logic gates. Fabricated with complementary N- and P-channel enhancement mode MOS transistors, it provides standard B-series buffered outputs for high output drive and symmetrical transition times.

Operating across an expansive supply voltage span of $3.0\text{V}$ to $18.0\text{V}$ DC, the CD4081B is ideal for high-noise industrial controls, 12V automotive electronics, battery-powered systems, and legacy digital logic interfacing where low static power dissipation and wide operating margins are required.

Quick reference


Supply Voltage Range (`VDD`)	3.0 V to 18.0 V DC (20.0 V maximum limit)
Logic Family	Standard CMOS 4000B Series
Gate Count	4 Independent 2-Input AND Gates
Logic Function	$Y = A \cdot B$
Propagation Delay ( $t_{pd}$ )	$60\text{ ns}$ typ at $VDD = 10\text{V}$ ( $120\text{ ns}$ at $5\text{V}$ )
Package Options	14-pin DIP / SOIC-14 / TSSOP-14
Noise Immunity	$0.45 \times V_{DD}$ typical

Pinout (DIP-14 Package)

text

             ┌───┴───┐
          1A 1│ 1   14│ VDD
          1B 2│       │13 4B
          1Y 3│       │12 4A
          2Y 4│CD4081B│11 4Y
          2A 5│       │10 3Y
          2B 6│       │9  3B
         VSS 7│       │8  3A
             └───────┘

Pin	Name	Type	Description
1, 2	`1A`, `1B`	Digital Input	Gate 1 Data Inputs
3	`1Y`	Digital Output	Gate 1 AND Output ( $1Y = 1A \cdot 1B$ )
4	`2Y`	Digital Output	Gate 2 AND Output ( $2Y = 2A \cdot 2B$ )
5, 6	`2A`, `2B`	Digital Input	Gate 2 Data Inputs
7	`VSS`	Power	Negative Supply / Ground reference (0 V)
8, 9	`3A`, `3B`	Digital Input	Gate 3 Data Inputs
10	`3Y`	Digital Output	Gate 3 AND Output ( $3Y = 3A \cdot 3B$ )
11	`4Y`	Digital Output	Gate 4 AND Output ( $4Y = 4A \cdot 4B$ )
12, 13	`4A`, `4B`	Digital Input	Gate 4 Data Inputs
14	`VDD`	Power	Positive Supply Voltage (+3.0 V to +18.0 V DC)

Function Table

Input A	Input B	Output Y ( $A \cdot B$ )
Low ( $L$ )	Low ( $L$ )	Low ( $L$ )
Low ( $L$ )	High ( $H$ )	Low ( $L$ )
High ( $H$ )	Low ( $L$ )	Low ( $L$ )
High ( $H$ )	High ( $H$ )	High ( $H$ )

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Supply Voltage	$V_{DD}$	3.0	—	18.0	V	Operating DC voltage
Low-Level Input Voltage	$V_{IL}$	—	—	1.5	V	$V_{DD} = 5\text{V}, V_O = 0.5\text{V}$
High-Level Input Voltage	$V_{IH}$	3.5	—	—	V	$V_{DD} = 5\text{V}, V_O = 4.5\text{V}$
Output Sink Current	$I_{OL}$	0.51	1.0	—	mA	$V_{DD} = 5\text{V}, V_{OUT} = 0.4\text{V}$
Output Source Current	$I_{OH}$	-0.51	-1.0	—	mA	$V_{DD} = 5\text{V}, V_{OUT} = 4.6\text{V}$
Propagation Delay	$t_{PLH}, t_{PHL}$	—	120	250	ns	$V_{DD} = 5\text{V}, C_L = 50\text{ pF}$
Propagation Delay (10V)	$t_{PLH}, t_{PHL}$	—	60	120	ns	$V_{DD} = 10\text{V}, C_L = 50\text{ pF}$
Quiescent Device Current	$I_{DD}$	—	0.02	1.0	µA	$V_{DD} = 5\text{V}, 25^\circ\text{C}$

Common mistakes

Leaving unused gate inputs floating: In high-impedance CMOS devices, open inputs drift randomly between logic levels, causing excessive power dissipation and oscillation. Tie all unused input pins ( $A$ and $B$ ) directly to VSS (GND) or VDD.
Assuming TTL output drive strength: While 74HC series ICs can source/sink $>5\text{ mA}$ , standard CD4000B CMOS outputs only drive $\sim 1\text{ mA}$ at $5\text{V}$ . Use a buffer (such as CD4050B or a 2N7000 MOSFET) when driving relays, optocouplers, or high-current LEDs directly.
Powering from 5V while driving from 12V without level shifting: Input voltages must not exceed $V_{DD} + 0.5\text{V}$ . Driving a 5V-powered CD4081 from a 12V sensor will forward-bias the internal ESD protection diode.

Notes

CD4081B vs 74HC08: The 74HC08 is much faster ( $t_{pd} \approx 9\text{ ns}$ vs $120\text{ ns}$ ) but is limited to $2\text{V} \dots 6\text{V}$ operation. The CD4081B supports up to $18\text{V}$ supplies.