onsemi MC74ACT04D Hex Inverter: Datasheet, Pinout, and Application Circuit Guide

The MC74ACT04D from onsemi is a high-performance, hex inverter integrated circuit belonging to the advanced ACT logic family. This device is a cornerstone in digital design, featuring six independent inverters (NOT gates) within a single 14-pin package. Its ability to provide high speed and low power consumption while maintaining compatibility with TTL levels makes it an extremely versatile component for a vast array of applications, from simple signal conditioning to complex clock distribution networks.

This guide provides a detailed overview of its datasheet specifications, pinout configuration, and practical application circuits.

Datasheet Overview and Key Specifications

The MC74ACT04D is designed to operate with a 5V power supply, typical for most ACT and TTL logic circuits. Understanding its absolute maximum ratings and recommended operating conditions is crucial for reliable circuit design.

Key Electrical Characteristics:

Supply Voltage (VCC): 4.5V to 5.5V

High-Level Input Voltage (VIH): Min. 2.0V

Low-Level Input Voltage (VIL): Max. 0.8V

High-Level Output Voltage (VOH): Typically 3.85V (at IOH = -24mA, VCC=4.5V)

Low-Level Output Voltage (VOL): Typically 0.44V (at IOL=24mA, VCC=4.5V)

Propagation Delay (tPD): Typically 5.5 ns (at VCC=5V, CL=50pF), enabling high-speed operation.

TTL-Compatible Inputs: The inputs are compatible with TTL logic levels, allowing it to seamlessly interface with a wide range of older and newer logic devices.

The device is offered in a standard SOIC-14 package (D suffix), which is suitable for automated PCB assembly. It is characterized for operation from -40°C to +85°C, making it robust for industrial environments.

Pinout Configuration

The pinout of the MC74ACT04D is straightforward and follows a common pattern for hex inverter ICs. The 14-pin Dual-Inline Package (DIP) or SOIC package has the following arrangement:

Pin 1 (A1): Input for Inverter 1

Pin 2 (Y1): Output for Inverter 1

Pin 3 (A2): Input for Inverter 2

Pin 4 (Y2): Output for Inverter 2

Pin 5 (A3): Input for Inverter 3

Pin 6 (Y3): Output for Inverter 3

Pin 7 (GND): Ground (0V Reference)

Pin 8 (Y4): Output for Inverter 4

Pin 9 (A4): Input for Inverter 4

Pin 10 (Y5): Output for Inverter 5

Pin 11 (A5): Input for Inverter 5

Pin 12 (Y6): Output for Inverter 6

Pin 13 (A6): Input for Inverter 6

Pin 14 (VCC): Positive Supply Voltage (+5V)

Note: Unused inputs must never be left floating. They should be tied to VCC or GND through a resistor (e.g., 1kΩ to 10kΩ) to prevent erratic behavior due to noise.

Application Circuit Guide

The fundamental function of an inverter is to output a logic level that is the opposite of its input. This simple operation leads to numerous applications.

1. Basic Inverter Operation:

The most straightforward application is as a logic inverter. A logic HIGH (e.g., 5V) on an input pin (e.g., A1) will produce a logic LOW (e.g., ~0V) on its corresponding output pin (Y1), and vice-versa.

2. Crystal Oscillator Circuit:

One of the most common uses of the MC74ACT04D is to build a simple and stable crystal oscillator. One inverter is configured as a high-gain amplifier using a feedback resistor.

A resistor (Rf, typically 1MΩ to 10MΩ) is connected between the input and output of a single inverter, biasing it into its linear region.

A crystal is connected between the input and output.

Two small capacitors (e.g., 15pF to 22pF) are connected from each crystal terminal to ground, forming a pi-network with the crystal to achieve resonance.

The output is a clean, high-frequency square wave, which can be buffered by another inverter in the same package to provide a robust system clock signal.

3. Schmitt Trigger for Signal Debouncing:

While not a true Schmitt trigger inverter, a standard inverter like the MC74ACT04D can be configured to provide hysteresis and debounce noisy signals, such as those from mechanical switches.

This involves connecting a resistor network between the input and output of the gate. A large resistor (e.g., 100kΩ) from output back to the input creates positive feedback.

This increases the noise immunity by creating different switching thresholds for low-to-high and high-to-low transitions, effectively cleaning up slow or noisy input signals.

4. Waveform Shaping and Buffer:

The inverters can be used to square up slow-rise-time or analog signals, converting them into clean digital waveforms. When used as a buffer (two inverters in series), the IC can provide increased current drive capability to control LEDs or other loads that require more current than a microcontroller pin can supply.

ICGOODFIND Summary:

The onsemi MC74ACT04D remains a fundamental and highly reliable component in the digital designer's toolkit. Its high-speed performance, TTL compatibility, and versatile hex inverter configuration make it indispensable for applications ranging from basic logic inversion and clock generation to signal conditioning and buffering. Its robust design and wide operating temperature range ensure stability in both consumer and industrial electronic systems.

Keywords:

Hex Inverter

TTL-Compatible

Crystal Oscillator

Propagation Delay

SOIC-14