onsemi MC74AC02DG Quad 2-Input NOR Gate: Datasheet, Pinout, and Application Circuits

The MC74AC02DG from onsemi is a high-performance, quad 2-input NOR gate integrated circuit housed in a SOIC-14 package. As a member of the advanced high-speed AC logic family, this device is engineered to operate with a wide power supply range from 2.0V to 6.0V, making it exceptionally versatile for interfacing with both TTL and CMOS logic levels. Its key characteristics include high noise immunity and low power consumption, which are hallmarks of the AC series, ensuring reliable performance in noisy digital environments.

A primary strength of this IC is its robust output drive capability, allowing it to source or sink significant current, which is essential for driving multiple inputs or capacitive loads. This makes it suitable for a wide array of digital logic applications, from basic signal gating to more complex system control.

Pinout Configuration

The MC74AC02DG features 14 pins in a standard SOIC package. The pinout is as follows:

Pins 1, 4, 8, 11: NOR Gate Outputs (Y)

Pins 2, 5, 9, 12: NOR Gate Inputs (A)

Pins 3, 6, 10, 13: NOR Gate Inputs (B)

Pin 7: Ground (GND)

Pin 14: Positive Power Supply (VCC)

This configuration provides four independent NOR gates, offering designers maximum flexibility within a single, compact IC.

Key Datasheet Specifications

Critical parameters from the datasheet define the IC's operational limits and performance:

Supply Voltage Range (VCC): 2.0V to 6.0V

High-Level Output Current (IOH): -24 mA

Low-Level Output Current (IOL): 24 mA

Propagation Delay (tPD): Typically 5.5 ns at 5V

Operating Temperature Range: -40°C to +85°C

These specifications highlight the device's ability to drive heavy loads with minimal signal delay, which is crucial for high-speed digital systems.

Application Circuits

The NOR gate is a fundamental building block in digital design. The MC74AC02DG can be used to construct various functional circuits.

1. Basic Logic Function: The primary function is to perform the logical NOR operation. The output is HIGH only when both inputs are LOW. For any other input combination, the output is LOW.

2. Set-Reset (SR) Latch: Two cross-coupled NOR gates can form a simple SR latch, a fundamental memory element. This circuit can store a single bit of data and is the basis for more complex flip-flops.

3. Oscillator / Pulse Generator: By connecting the output of one NOR gate back to its input through a resistor and capacitor (RC network), a simple astable multivibrator can be created. This circuit generates a continuous stream of square waves, useful for creating clock signals.

4. Signal Gating and Control: NOR gates are perfect for enabling or disabling the passage of a digital signal based on a control input, often used in data routing and multiplexing applications.

ICGOODFIND Summary

The onsemi MC74AC02DG is a highly reliable and versatile quad 2-input NOR gate IC. Its excellent noise margin, high-speed operation, and strong output drive make it an ideal choice for a vast spectrum of digital design projects, from basic logic implementation to creating memory elements and clock generators. Its compatibility with a broad voltage range ensures easy integration into both 3.3V and 5V systems, solidifying its position as a fundamental component for engineers and hobbyists alike.

Keywords: NOR Gate, MC74AC02DG, CMOS Logic, SOIC-14, Digital IC