onsemi MC74HC04ADG Hex Inverter: Datasheet, Application Circuit, and Pinout Configuration
The MC74HC04ADG from onsemi is a member of the 74HC04 family, representing one of the most fundamental and widely used integrated circuits in digital electronics. This device is a hex inverter, meaning it contains six independent NOT gates within a single package. Each gate performs the Boolean function Y = Ā, where the output is the inverse of its input. Housed in a SOIC-14 package, this IC is designed for general-purpose logic inversion applications in a broad range of systems, from consumer electronics to industrial controls.
Pinout Configuration
Understanding the pinout is crucial for proper circuit design. The MC74HC04ADG is supplied in a 14-pin package with the following configuration:
Pins 1, 3, 5, 9, 11, 13 (Inputs): The inputs to the six individual inverters (1A through 6A).
Pins 2, 4, 6, 8, 10, 12 (Outputs): The corresponding outputs for the inverters (1Y through 6Y).
Pin 7 (GND): Ground (0V reference).
Pin 14 (VCC): Positive supply voltage pin. The device is rated for a 2.0V to 6.0V operating range, making it compatible with various logic levels, including 5V TTL.
Datasheet Overview and Key Specifications
The datasheet provides all necessary information for designing a reliable circuit. Key absolute maximum ratings and electrical characteristics include:
Supply Voltage Range (VCC): -0.5V to +7.0V (absolute max), 2.0V to 6.0V (recommended operating).
High-Level Input Voltage (VIH): Minimum of 3.15V when VCC = 4.5V.
Low-Level Input Voltage (VIL): Maximum of 1.35V when VCC = 4.5V.
Propagation Delay (tPD): Typically 8 ns at VCC = 4.5V and room temperature, enabling high-speed operation.
Quiescent Current (ICC): Very low, typically 2 μA, which is excellent for low-power applications.
Operating Temperature Range: -40°C to +85°C, suitable for industrial environments.
Application Circuit: Crystal Oscillator
A classic application for a hex inverter like the MC74HC04ADG is building a simple crystal oscillator circuit, which provides a stable clock signal for microcontrollers and other digital systems.
Circuit Description:
1. Two of the six inverters (e.g., U1a and U1b) are used in this configuration.
2. The first inverter (U1a) is connected in a linear mode using feedback resistor R1 (1MΩ to 10MΩ). This resistor biases the inverter into its linear region of operation, allowing it to function as a high-gain amplifier.
3. A crystal resonator (e.g., 4MHz, 8MHz, etc.) is connected between the input and output of this first inverter.
4. Two small-value capacitors (C1 and C2, e.g., 22pF) are connected from each terminal of the crystal to ground. These capacitors form a pi-network with the crystal, determining the load capacitance and ensuring the circuit oscillates at the correct frequency.
5. The output of the first stage is fed into the input of the second inverter (U1b). This second stage acts as a buffer to square up the waveform, providing a clean, digital logic-level output for the rest of the system while isolating the oscillator from load variations.
This simple yet effective circuit highlights the utility of having multiple gates in a single IC, enabling complex functions with minimal components.
The onsemi MC74HC04ADG is a quintessential logic IC that offers high-speed performance, low power consumption, and significant design flexibility. Its robustness and compatibility with a wide voltage range make it an excellent choice for both prototyping and production. Whether used for simple signal inversion, building oscillators, or constructing waveform shaping circuits, this hex inverter remains a fundamental building block in the digital designer's toolkit.
Keywords: Hex Inverter, MC74HC04ADG, CMOS Logic, Crystal Oscillator, SOIC-14
