74390 - Dual Decade Counter Technical Summary

Overview

The 74390 is a high-speed, dual decade counter integrated circuit (IC) designed for digital counting applications. This component consists of two independent 4-bit decade counters, each capable of counting from 0 to 9 (BCD output) before resetting. The 74390 is part of the 7400 series of logic devices and is widely used in frequency division, timing circuits, and digital display systems. Its high-speed operation makes it suitable for applications requiring precise and rapid counting.

Built with advanced semiconductor technology, the 74390 offers reliable performance, low power consumption, and compatibility with TTL (Transistor-Transistor Logic) voltage levels. Its dual-counter configuration allows for cascading or independent operation, providing flexibility in system design.

Features

• Dual Decade Counters: Contains two independent 4-bit BCD counters in a single package.
• High-Speed Operation: Optimized for fast counting applications with minimal propagation delay.
• TTL-Compatible Inputs/Outputs: Works seamlessly with standard TTL logic levels (0V to 5V).
• Asynchronous Clear: Each counter includes a reset input for immediate clearing of the count.
• Cascadable Design: Multiple 74390 ICs can be cascaded for extended counting ranges.
• Wide Operating Voltage: Supports a supply voltage range of 4.75V to 5.25V.
• Low Power Consumption: Designed for energy-efficient operation in digital systems.
• Standard 16-Pin Package: Available in DIP (Dual In-line Package) and SOIC (Small Outline IC) formats.

Applications

The 74390 is versatile and finds use in a variety of digital and timing applications, including:

• Frequency Dividers: Used to divide clock signals in digital circuits.
• Digital Clocks: Integral part of timing circuits in clocks and counters.
• Event Counters: Tracks occurrences of events in industrial and consumer electronics.
• Display Drivers: Drives seven-segment displays in counting applications.
• Industrial Control Systems: Provides counting functionality in automation and control systems.
• Educational Kits: Commonly used in electronics training and prototyping.

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): 2.0V (min)
• Low-Level Input Voltage (Vil): 0.8V (max)
• High-Level Output Current (Ioh): -0.4mA
• Low-Level Output Current (Iol): 8mA

Timing Characteristics

• Maximum Clock Frequency: 32MHz (typical)
• Propagation Delay (Clock to Output): 15ns (max)
• Reset Pulse Width: 30ns (min)

Package Information

The 74390 is available in multiple package options to suit different assembly and mounting requirements. Below are the most common package details:

16-Pin DIP (Dual In-line Package)

• Package Code: N
• Dimensions: 19.3mm x 6.35mm
• Pin Spacing: 2.54mm (standard DIP pitch)
• Material: Plastic (PDIP)

16-Pin SOIC (Small Outline IC)

• Package Code: D
• Dimensions: 9.9mm x 3.9mm
• Pin Spacing: 1.27mm
• Material: Plastic (SOIC)

Pin Configuration

The pinout for the 74390 is as follows:

• Pin 1: Clock Input A (Counter 1)
• Pin 2: Reset Input A (Counter 1)
• Pin 3: Output QA (Counter 1, LSB)
• Pin 4: Output QB (Counter 1)
• Pin 5: Output QC (Counter 1)
• Pin 6: Output QD (Counter 1, MSB)
• Pin 7: Ground (GND)
• Pin 8: Output QD (Counter 2, MSB)
• Pin 9: Output QC (Counter 2)
• Pin 10: Output QB (Counter 2)
• Pin 11: Output QA (Counter 2, LSB)
• Pin 12: Reset Input B (Counter 2)
• Pin 13: Clock Input B (Counter 2)
• Pin 14: Vcc (Supply Voltage)
• Pin 15: Not Connected (NC)
• Pin 16: Not Connected (NC)

Conclusion

The 74390 dual decade counter is a reliable and high-performance IC suitable for a wide range of digital counting applications. Its dual-counter design, high-speed operation, and TTL compatibility make it a preferred choice for engineers and hobbyists alike. Whether used in frequency division, digital clocks, or industrial control systems, the 74390 delivers consistent and accurate counting functionality. Available in standard DIP and SOIC packages, it offers flexibility for both prototyping and production environments.