74393 Technical Summary

74393 - Dual 4-Bit Binary Counter Technical Summary

Overview

The 74393 is a high-speed, dual 4-bit binary counter integrated circuit (IC) belonging to the 7400 series of TTL logic devices. This component consists of two independent 4-bit ripple counters, each with a clear function, making it highly versatile for digital counting applications. The 74393 is designed for high-speed operation, ensuring reliable performance in time-critical systems.

Each counter within the 74393 features a clock input (CP), a master reset input (MR), and four parallel outputs (Q0-Q3). The counters operate in a ripple fashion, meaning each flip-flop output serves as the clock input for the subsequent stage. This design allows for efficient counting operations while maintaining simplicity in implementation.

Features

Dual 4-Bit Counters: Contains two independent 4-bit binary counters in a single package.
High-Speed Operation: Optimized for fast counting applications with minimal propagation delay.
Asynchronous Master Reset: Each counter includes a reset input (MR) to clear all outputs to a low state.
Wide Operating Voltage: Compatible with standard TTL voltage levels (4.75V to 5.25V).
Ripple Clocking: Internal ripple carry allows cascading for higher-bit counters.
Standard Pin Configuration: Follows industry-standard pinouts for easy integration into existing designs.
Low Power Consumption: Designed for efficient power usage in digital systems.

Applications

The 74393 is widely used in digital systems where counting or frequency division is required. Key applications include:

Frequency Dividers: Used to divide clock signals in digital circuits.
Event Counters: Tracks occurrences of specific events in embedded systems.
Timing Circuits: Provides timing functions in microcontroller-based applications.
Industrial Control Systems: Used in automation for counting operations.
Digital Clocks: Forms part of the counter chain in clock generation circuits.
Data Processing Units: Facilitates address generation and sequence control.

Electrical Characteristics

Absolute Maximum Ratings

Supply Voltage (Vcc): 7V
Input Voltage (Vin): 5.5V
Operating Temperature Range: 0°C to 70°C (Commercial grade)
Storage Temperature Range: -65°C to 150°C

Recommended Operating Conditions

Supply Voltage (Vcc): 4.75V to 5.25V
High-Level Input Voltage (Vih): 2V (min)
Low-Level Input Voltage (Vil): 0.8V (max)
Clock Frequency (fclk): Up to 32MHz (typical)

DC Characteristics

High-Level Output Voltage (Voh): 2.4V (min) at Ioh = -0.4mA
Low-Level Output Voltage (Vol): 0.4V (max) at Iol = 8mA
Input Leakage Current (Iin): ±1μA (max) at Vin = 0V to 5.5V
Supply Current (Icc): 8mA (typical) per counter at 1MHz

AC Characteristics

Propagation Delay (CP to Q0): 15ns (typical)
Maximum Clock Frequency: 32MHz (typical)
Reset Pulse Width: 25ns (min)
Setup Time (MR to CP): 20ns (min)

Package Information

The 74393 is available in multiple package options to suit different application requirements:

14-Pin DIP (Dual Inline Package):
- Standard through-hole package
- 0.3" row spacing
- Widely used for prototyping and breadboarding
14-Pin SOIC (Small Outline IC):
- Surface-mount package
- Reduced footprint for space-constrained designs
- 3.9mm body width
14-Pin TSSOP (Thin Shrink Small Outline Package):
- Ultra-thin surface-mount variant
- 4.4mm body width
- Ideal for high-density PCB layouts

Pin Configuration

The 74393 features the following pinout configuration:

Pin 1: CP1 (Clock input for Counter 1)
Pin 2: MR1 (Master Reset for Counter 1)
Pin 3: Q0 (Output bit 0 for Counter 1)
Pin 4: Q1 (Output bit 1 for Counter 1)
Pin 5: Q2 (Output bit 2 for Counter 1)
Pin 6: Q3 (Output bit 3 for Counter 1)
Pin 7: GND (Ground)
Pin 8: Q3 (Output bit 3 for Counter 2)
Pin 9: Q2 (Output bit 2 for Counter 2)
Pin 10: Q1 (Output bit 1 for Counter 2)
Pin 11: Q0 (Output bit 0 for Counter 2)
Pin 12: MR2 (Master Reset for Counter 2)
Pin 13: CP2 (Clock input for Counter 2)
Pin 14: Vcc (Positive supply voltage)

Functional Description

Each 4-bit counter in the 74393 operates as an asynchronous (ripple) counter. The clock signal (CP) triggers the first flip-flop (Q0), with each subsequent flip-flop being clocked by the output of the previous stage. This ripple effect creates a binary count sequence from 0000 to 1111 (0 to 15 in decimal).

The master reset input (MR), when brought high, asynchronously clears all flip-flop outputs (Q0-Q3) to low. The reset function is independent of the clock state, providing immediate clearing capability when needed.

For extended counting applications, multiple 74393 ICs can be cascaded by connecting the Q3 output of one counter to the CP input of the next, creating 8-bit, 12-bit, or larger counters as required by the application.