LM3302N Quad Independent Precision Voltage Comparator

Overview

The LM3302N is part of the LM139 series of precision voltage comparators, featuring four independent comparators in a single package. Designed for versatile operation, these comparators offer outstanding performance with an exceptionally low offset voltage specification of just 2 mV maximum across all four comparators. The device is engineered to operate efficiently from a single power supply across a broad voltage range, while also supporting split power supply configurations. A standout feature is its ability to handle input common-mode voltages that include ground, even when powered from a single supply, making it exceptionally flexible for various circuit designs.

Key Features

• Wide Supply Voltage Range: Operates from 2V to 36V DC, accommodating a variety of power supply configurations.
• Low Offset Voltage: Maximum offset voltage of 2 mV ensures high precision in comparison tasks.
• Single or Split Supply Operation: Supports both single and dual power supply setups, providing design flexibility.
• Ground-Inclusive Input Range: Input common-mode voltage range includes ground, even when using a single power supply.
• Low Power Consumption: Power supply current drain remains low and is independent of the supply voltage magnitude.
• Independent Comparators: Four separate comparators in one package allow for multiple simultaneous comparisons.

Applications

The LM3302N is suitable for a wide range of applications, including but not limited to:

• Voltage level detection and monitoring
• Analog-to-digital conversion circuits
• Oscillators and waveform generators
• Signal conditioning circuits
• Battery-powered and portable devices
• Industrial control systems
• Automotive electronics
• Threshold detectors

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VCC): 36V
• Input Differential Voltage: ±36V
• Input Common-Mode Voltage: -0.3V to VCC + 0.3V
• Output Short-Circuit Duration: Continuous (to ground)
• Operating Temperature Range: -25°C to +85°C
• Storage Temperature Range: -65°C to +150°C

Typical Operating Characteristics

• Input Offset Voltage: 1 mV (typical), 2 mV (max)
• Input Bias Current: 25 nA (typical)
• Input Offset Current: 5 nA (typical)
• Response Time (for 100 mV overdrive): 1.3 μs (typical)
• Supply Current (per comparator): 0.8 mA (typical)
• Output Saturation Voltage (Isink = 4 mA): 250 mV (typical)

Package Information

14-Pin DIP (Dual Inline Package)

• Package Type: PDIP-14
• Dimensions: 19.3 mm x 6.35 mm
• Pin Pitch: 2.54 mm
• Material: Molded Plastic
• Lead Finish: Matte Tin

Pin Configuration

• Pin 1: Output 1
• Pin 2: Inverting Input 1
• Pin 3: Non-Inverting Input 1
• Pin 4: VCC+ (Positive Supply Voltage)
• 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- (Negative Supply Voltage or Ground)
• Pin 12: Non-Inverting Input 4
• Pin 13: Inverting Input 4
• Pin 14: Output 4

Detailed Description

The LM3302N integrates four high-precision voltage comparators in a single 14-pin package, making it an efficient solution for space-constrained applications. Each comparator is designed to compare two voltage inputs and provide a digital output indicating which input is higher. The device's ability to operate from a single power supply while accommodating input voltages that include ground makes it particularly useful in battery-operated and portable electronics.

The comparators feature low input bias and offset currents, minimizing errors in precision applications. The fast response time of 1.3 μs (typical) ensures quick decision-making in dynamic environments. Additionally, the output stage is capable of sinking sufficient current to drive various loads, including LEDs, relays, and other logic circuits.

Design Considerations

Power Supply Decoupling

To ensure stable operation, it is recommended to place a 0.1 μF ceramic capacitor close to the power supply pins (VCC+ and VCC-) to decouple high-frequency noise.

Input Protection

Although the LM3302N has a wide input voltage range, care should be taken to avoid exceeding the absolute maximum ratings. In harsh environments, external clamping diodes or series resistors may be used to protect the inputs.

Output Load Considerations

The output stage is designed to sink current. When driving inductive loads such as relays, a freewheeling diode should be used to protect the output from voltage spikes.

Conclusion

The LM3302N is a versatile and reliable quad voltage comparator suitable for a wide range of applications. Its combination of low offset voltage, wide supply range, and flexible operation makes it an excellent choice for precision analog circuits. Whether used in industrial controls, automotive systems, or portable devices, the LM3302N delivers consistent performance and robust functionality.