74HC393 — Dual 4-Bit Binary Ripple Counter

Overview

The 74HC393 (SN74HC393N) is a dual 4-bit binary ripple counter IC manufactured by Texas Instruments, Nexperia, and ON Semiconductor. Containing two independent 4-bit binary ripple counters in a single 14-pin package, it divides incoming clock frequencies by $2, 4, 8, 16$ (per counter channel).

Operating from 2.0V to 6.0V DC, each counter is triggered on negative-going clock edges ( $\overline{1CLK}, \overline{2CLK}$ ) and includes an active-HIGH asynchronous master clear pin ( $1CLR, 2CLR$ ). By connecting the MSB output of the first stage ( $1Q_D$ ) to the clock input of the second stage ( $\overline{2CLK}$ ), the two 4-bit counters form a single 8-bit binary counter ( $0 \dots 255$ ).

Quick reference


Supply Voltage (`VCC`)	2.0 V to 6.0 V DC
Logic Family	High-Speed CMOS (74HC) / TTL Compatible (74HCT)
Channels	2 Independent 4-Bit Binary Ripple Counters ( $1Q_A \dots 1Q_D$ and $2Q_A \dots 2Q_D$ )
Cascaded Mode	8-Bit Binary Counter ( $00000000_2 \dots 11111111_2$ )
Clock Input Trigger	Negative-Edge Triggered ( $\downarrow$ HIGH-to-LOW transition)
Clear Input	Asynchronous Active-HIGH Master Clear ( $1CLR, 2CLR$ )
Clock Frequency	Up to $40\text{ MHz}$ at $VCC = 4.5\text{V}$
Package	14-pin DIP / SOIC-14 / TSSOP-14

Pinout (DIP-14 Package)

text

             ┌───┴───┐
       /1CLK 1│ 1   14│ VCC (+2V to +6V)
        1CLR 2│       │13 /2CLK
         1QA 3│ 74HC  │12 2CLR
         1QB 4│  393  │11 2QA
         1QC 5│       │10 2QB
         1QD 6│       │9  2QC
         GND 7│       │8  2QD
             └───────┘

Pin	Name	Type	Description
1	`\1CLK`	Input	Counter 1 Clock Input (Negative-edge triggered $\downarrow$ )
2	`1CLR`	Input	Counter 1 Reset Input (Active HIGH: High = Reset $1Q_A \dots 1Q_D$ to $0000_2$ )
3–6	`1QA, 1QB, 1QC, 1QD`	Output	Counter 1 Binary Outputs ( $1Q_A$ LSB, $1Q_D$ MSB)
7	`GND`	Power	Ground reference (0 V)
8–11	`2QD, 2QC, 2QB, 2QA`	Output	Counter 2 Binary Outputs ( $2Q_A$ LSB, $2Q_D$ MSB)
12	`2CLR`	Input	Counter 2 Reset Input (Active HIGH)
13	`\2CLK`	Input	Counter 2 Clock Input (Negative-edge triggered $\downarrow$ )
14	`VCC`	Power	Positive Power Supply (+2.0V to +6.0V DC)

8-Bit Counter Cascading Diagram