onsemi MC74HC04AD Hex Inverter: Datasheet, Pinout, and Application Circuit Guide
The MC74HC04AD from onsemi is a member of the 74HC high-speed CMOS logic family, integrating six independent inverting buffers (NOT gates) into a single compact package. This IC is renowned for its wide operating voltage range (2V to 6V), low power consumption, and high noise immunity, making it a fundamental component in countless digital systems. This guide provides an overview of its key specifications, pinout configuration, and a classic application circuit.
Datasheet Overview and Key Specifications
The datasheet for the MC74HC04AD details its electrical characteristics and absolute maximum ratings. Key parameters that define its performance include:
Logic Type: Inverter / NOT Gate
Number of Circuits: 6
Technology: High-Speed CMOS (HC)
Supply Voltage Range (VCC): 2.0 V to 6.0 V
Low Power Consumption: Very low static power dissipation (e.g., 2 µA max. @ 5V)
Output Drive Capability: Can drive up to 10 LSTTL loads
High Noise Immunity: Characteristic of CMOS technology
Operating Temperature Range: -55°C to +125°C
Package: SOIC-14, a surface-mount package ideal for automated assembly.
These specs make the MC74HC04AD compatible with a broad spectrum of logic levels and suitable for both battery-powered and line-operated equipment.
Pinout Configuration
Understanding the pinout is crucial for circuit design. The MC74HC04AD comes in a 14-pin SOIC package. The pin assignments are as follows:
Pin 1 (Input A1): Input of the first inverter.
Pin 2 (Output Y1): Output of the first inverter.
Pin 3 (Input A2): Input of the second inverter.
Pin 4 (Output Y2): Output of the second inverter.
Pin 5 (Input A3): Input of the third inverter.
Pin 6 (Output Y3): Output of the third inverter.
Pin 7 (GND): Ground (0V reference).
Pin 8 (Output Y4): Output of the fourth inverter.
Pin 9 (Input A4): Input of the fourth inverter.
Pin 10 (Output Y5): Output of the fifth inverter.
Pin 11 (Input A5): Input of the fifth inverter.
Pin 12 (Output Y6): Output of the sixth inverter.
Pin 13 (Input A6): Input of the sixth inverter.
Pin 14 (VCC): Positive supply voltage (2V to 6V).
The pinout follows a standard, logical layout, with each inverter's input and output positioned adjacently.
Classic Application Circuit: Simple Crystal Oscillator
A quintessential use for a hex inverter is building a crystal oscillator circuit, which provides a stable and precise clock signal for microcontrollers and digital systems.
Circuit Components:
IC1: MC74HC04AD Hex Inverter
Crystal: 4 MHz (or any desired frequency within the IC's operational limits)
R1: 1 MΩ Resistor
C1, C2: 22 pF Ceramic Capacitors
Circuit Operation:
1. One of the six inverters (e.g., U1A) is configured as a linear amplifier by connecting the feedback resistor R1 between its input (Pin 1) and output (Pin 2). This biases the inverter into its active region.
2. The crystal is connected between the input (Pin 1) and output (Pin 2), forming the frequency-determining element of the oscillator.
3. Capacitors C1 and C2 are connected from each terminal of the crystal to ground. These load capacitors are critical for ensuring the oscillator starts reliably and runs at the correct frequency.
4. The resulting clean, oscillating waveform appears at the output (Pin 2). This signal can then be buffered by another inverter within the same package (e.g., U1B) to square up the waveform and provide a stronger output drive capability for subsequent stages.
This simple yet effective circuit highlights the versatility of the MC74HC04AD beyond mere logic inversion.
ICGOODFIND: The onsemi MC74HC04AD stands as an exceptionally versatile and robust hex inverter IC. Its combination of wide voltage operation, low power consumption, and high noise immunity ensures its continued relevance as a fundamental building block for signal conditioning, oscillator design, and general-purpose logic inversion across a vast array of consumer and industrial electronic products.
Keywords: MC74HC04AD, Hex Inverter, CMOS Logic, Crystal Oscillator, SOIC-14
