LM324N

LM324N - Low Power Quad Operational Amplifier

Overview

The LM324N is a monolithic integrated circuit containing four independent, high-gain operational amplifiers designed to operate from a single power supply over a wide voltage range. These internally frequency-compensated op-amps provide excellent performance for general-purpose analog circuit applications while consuming minimal power. The device offers significant advantages in battery-operated systems and other power-sensitive designs due to its low current drain, which remains stable regardless of power supply voltage.

As part of the LM124 series, the LM324N features wide power supply ranges from 3V to 32V with single supply operation (or ±1.5V to ±16V with split supplies). The amplifiers maintain their specifications across the entire temperature range from 0°C to 70°C, making them suitable for commercial-grade applications. The quad configuration in a single package provides excellent space efficiency for multi-channel designs.

Key Features

• Four internally compensated op-amps in single package
• Wide power supply range: 3V to 32V single supply (±1.5V to ±16V dual supply)
• Low supply current drain: 0.8mA per amplifier (typical)
• Unity-gain bandwidth: 1MHz (typical)
• Large output voltage swing: 0V to V+ - 1.5V
• Low input bias current: 45nA (typical)
• Input common-mode voltage range includes ground
• Differential input voltage range equal to power supply voltage
• Internal frequency compensation for unity gain stability
• Direct replacement for MC3403, RM2902, and similar quad op-amps

Applications

The LM324N's combination of features makes it ideal for numerous analog signal processing applications across multiple industries:

• Transducer amplifiers: Ideal for amplifying signals from sensors and transducers
• DC gain blocks: Provides stable amplification for low-frequency signals
• Active filters: Suitable for implementing various filter topologies
• Signal conditioning circuits: Used in instrumentation and measurement systems
• Voltage followers: Creates high-impedance buffers
• Industrial control systems: Used in process control and automation
• Consumer electronics: Found in audio equipment, power supplies, and battery chargers
• Automotive systems: Used in sensor interfaces and control modules
• Medical devices: Suitable for low-power biomedical instrumentation

Electrical Characteristics

The following table summarizes key electrical specifications (VCC = 5V, TA = 25°C unless otherwise noted):

• Input Offset Voltage: 2mV (typical), 7mV (maximum)
• Input Bias Current: 45nA (typical), 250nA (maximum)
• Input Offset Current: 5nA (typical), 50nA (maximum)
• Common Mode Rejection Ratio: 70dB (typical)
• Supply Voltage Rejection Ratio: 65dB (typical)
• Large Signal Voltage Gain: 100V/mV (typical) at VCC = 15V, RL ≥ 2kΩ
• Output Voltage Swing: 0V to VCC - 1.5V (typical)
• Slew Rate: 0.5V/μs (typical)
• Gain Bandwidth Product: 1MHz (typical)
• Power Supply Current: 0.8mA per amplifier (typical)
• Input Common Mode Voltage Range: -0.3V to VCC - 1.5V
• Differential Input Voltage Range: Equal to power supply voltage
• Output Short Circuit Current: 40mA (typical)

Package Information

The LM324N is available in multiple package options to suit different application requirements:

• PDIP-14: Plastic Dual In-line Package (300mil body width)
• SOIC-14: Small Outline Integrated Circuit (150mil body width)
• TSSOP-14: Thin Shrink Small Outline Package (4.4mm body width)

Pin Configuration (PDIP-14):

• Pin 1: Output 1
• Pin 2: Inverting Input 1
• Pin 3: Non-Inverting Input 1
• Pin 4: VCC+
• Pin 5: Non-Inverting Input 2
• Pin 6: Inverting Input 2
• Pin 7: Output 2
• Pin 8: Output 3
• Pin 9: Inverting Input 3
• Pin 10: Non-Inverting Input 3
• Pin 11: VCC- or GND
• Pin 12: Non-Inverting Input 4
• Pin 13: Inverting Input 4
• Pin 14: Output 4

Design Considerations

When implementing the LM324N in circuit designs, several important factors should be considered:

• Power Supply Decoupling: Proper bypass capacitors (0.1μF ceramic) should be placed close to the power pins to ensure stable operation.
• Output Loading: The output stage can source up to 20mA and sink up to 10mA while maintaining specified performance.
• Input Protection: While the inputs are protected against excessive differential voltages, input currents should be limited to 10mA maximum.
• PCB Layout: Careful layout practices should be followed to minimize noise pickup and ensure proper thermal dissipation.
• Temperature Effects: Parameters such as input offset voltage and bias current vary with temperature and should be considered in precision applications.

Reliability and Quality

The LM324N is manufactured using high-reliability processes and meets or exceeds industry standards for quality and performance. Key reliability features include:

• ESD protection on all pins (≥1000V Human Body Model)
• Wide operating temperature range (0°C to 70°C commercial grade)
• Extended temperature versions available (LM324A: -40°C to 125°C)
• Robust output short-circuit protection
• No latch-up when common-mode range is exceeded

Conclusion

The LM324N quad operational amplifier provides an excellent combination of performance, versatility, and cost-effectiveness for a wide range of analog circuit applications. Its ability to operate from single or split power supplies, low power consumption, and robust design make it particularly valuable in battery-powered systems and industrial control applications. With four amplifiers in a single package, the LM324N offers significant board space savings and simplified inventory management for designs requiring multiple op-amp channels.