74HC02 — Quad 2-Input NOR Gate

Overview

The 74HC02 (SN74HC02) is a quad 2-input NOR gate IC manufactured using high-speed silicon-gate CMOS technology. Containing four independent 2-input NOR gates in a 14-pin DIP/SOIC package, it performs the Boolean function $Y = \overline{A + B}$ in positive logic.

Like the NAND gate, the NOR gate is a universal logic gate capable of implementing any Boolean function without other gate types. Operating across a supply voltage range of 2.0V to 6.0V DC, the 74HC02 features low CMOS power consumption and high switching speeds ( $7\text{ ns}$ propagation delay).

Quick reference


Supply Voltage (`VCC`)	2.0 V to 6.0 V DC
Logic Family	High-Speed CMOS (74HC) / TTL Compatible (74HCT)
Independent Gates	4 (Quad 2-Input NOR)
Propagation Delay	$7\text{ ns}$ typical at $VCC = 5.0\text{V}$
Output Drive Current	$\pm 5.2\text{ mA}$ at $VCC = 4.5\text{V}$
Package	14-pin DIP / SOIC-14 / TSSOP-14

Pinout (DIP-14 Package)

text

             ┌───┴───┐
         1/Y 1│ 1   14│ VCC
          1A 2│       │13 4/Y
          1B 3│       │12 4B
         2/Y 4│ 74HC02│11 4A
          2A 5│       │10 3/Y
          2B 6│       │9  3B
         GND 7│       │8  3A
             └───────┘

Important Pinout Note: On 74HC02, outputs are on Pins 1, 4, 10, 13, and inputs are on Pins 2/3, 5/6, 8/9, 11/12 (unlike 74HC00/08/32 where inputs are on Pins 1/2)!

Pin	Name	Description
1	`1/Y`	Gate 1 Output ( $1Y = \overline{1A + 1B}$ )
2	`1A`	Gate 1 Input A
3	`1B`	Gate 1 Input B
4	`2/Y`	Gate 2 Output ( $2Y = \overline{2A + 2B}$ )
5	`2A`	Gate 2 Input A
6	`2B`	Gate 2 Input B
7	`GND`	Ground reference (0 V)
8	`3A`	Gate 3 Input A
9	`3B`	Gate 3 Input B
10	`3/Y`	Gate 3 Output ( $3Y = \overline{3A + 3B}$ )
11	`4A`	Gate 4 Input A
12	`4B`	Gate 4 Input B
13	`4/Y`	Gate 4 Output ( $4Y = \overline{4A + 4B}$ )
14	`VCC`	Power supply voltage (+2.0V to +6.0V DC)

Function & Truth Table (Per Gate)

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

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Supply Voltage	$V_{CC}$	2.0	5.0	6.0	V	DC
High-Level Input Voltage	$V_{IH}$	3.15	—	—	V	$V_{CC} = 4.5\text{V}$
Low-Level Input Voltage	$V_{IL}$	—	—	1.35	V	$V_{CC} = 4.5\text{V}$
Propagation Delay ( $A,B \rightarrow Y$ )	$t_{PD}$	—	7	15	ns	$V_{CC} = 4.5\text{V}, C_L = 50\text{pF}$
Output Drive Current	$I_{OUT}$	—	—	$\pm 5.2$	mA	$V_{CC} = 4.5\text{V}$
Quiescent Supply Current	$I_{CC}$	—	—	2.0	µA	$V_{IN} = V_{CC}\text{ or GND}$

Typical Applications

Active-HIGH SR Latch (Flip-Flop)

Cross-coupling two NOR gates creates an active-HIGH Set-Reset ( $S$ - $R$ ) latch.