LM239N - Quad Differential Comparator

Overview

The LM239N is a quad differential comparator integrated circuit designed for precision voltage comparison applications. It consists of four independent voltage comparators that are designed to operate from a single power supply over a wide range of voltages. This device is particularly notable for its low input bias current, low input offset voltage, and fast response time, making it suitable for a variety of analog signal processing tasks.

Manufactured using advanced silicon processing technology, the LM239N offers excellent performance characteristics while maintaining low power consumption. The comparators feature open-collector outputs that can be wire-OR connected, providing flexibility in system design. The device is available in a standard 14-pin DIP package, making it compatible with through-hole PCB designs.

Features

• Four independent precision voltage comparators in single package
• Wide single supply voltage range: 2V to 36V
• Dual supply operation possible (±1V to ±18V)
• Low input bias current: 25nA typical
• Low input offset voltage: 2mV typical
• Input common-mode voltage range includes ground
• Differential input voltage range equal to power supply voltage
• Open-collector outputs for wired-OR connections
• Output compatible with TTL, MOS, and CMOS logic
• Low power consumption: 0.8mA per comparator typical
• Fast response time: 1.3μs typical for 5mV overdrive

Applications

The LM239N finds use in a wide variety of electronic systems requiring voltage comparison or analog-to-digital conversion functions:

• Voltage level detection and monitoring
• Zero-crossing detectors
• Analog-to-digital converters
• Pulse width modulators
• Oscillators and multivibrators
• Peak detectors
• Limit comparators
• Industrial control systems
• Automotive electronics
• Power supply monitoring circuits
• Signal conditioning circuits
• Window comparators

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VCC): 36V or ±18V
• Differential Input Voltage: 36V
• Input Voltage Range: -0.3V to +36V
• Output Sink Current: 16mA
• Operating Temperature Range: 0°C to +70°C
• Storage Temperature Range: -65°C to +150°C
• Lead Temperature (Soldering, 10 sec): 260°C

DC Electrical Characteristics

(VCC = 5V, TA = 25°C unless otherwise specified)

• Input Offset Voltage: 2mV (max 5mV)
• Input Bias Current: 25nA (max 100nA)
• Input Offset Current: 5nA (max 30nA)
• Input Common-Mode Voltage Range: 0V to VCC-1.5V
• Supply Current (all four comparators): 3.2mA (max 4.0mA)
• Output Saturation Voltage (Isink = 4mA): 0.25V (max 0.4V)
• Output Leakage Current (Vout = 36V): 0.1nA (max 25nA)

AC Electrical Characteristics

• Response Time (5mV overdrive): 1.3μs typical
• Propagation Delay (100mV overdrive): 300ns typical
• Output Rise Time (CL = 15pF): 40ns typical
• Output Fall Time (CL = 15pF): 25ns typical

Package Information

14-Pin DIP Package Dimensions

• Package Type: PDIP-14
• Length: 19.3mm (max)
• Width: 6.35mm (max)
• Height: 4.57mm (max)
• Lead Pitch: 2.54mm
• Lead Width: 0.38mm (min)
• Lead Length: 3.3mm (min)
• Package Material: Molded Plastic

Pin Configuration

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

Design Considerations

When implementing the LM239N in circuit designs, several important factors should be considered:

Power Supply Decoupling

A 0.1μF ceramic capacitor should be placed as close as possible to the power supply pins to minimize noise and ensure stable operation. For applications with long power supply leads or particularly noisy environments, additional bulk capacitance may be required.

Output Configuration

The open-collector outputs require pull-up resistors for proper operation. The value of these resistors should be chosen based on the desired switching speed and power consumption. Typical values range from 1kΩ to 10kΩ, with lower values providing faster switching but higher power dissipation.

Input Protection

While the LM239N has built-in input protection diodes, additional external protection may be required in harsh environments or when the inputs might be subjected to voltages beyond the absolute maximum ratings. Series input resistors can help limit current through the protection diodes.

PCB Layout

Proper PCB layout techniques should be employed to minimize noise and ensure reliable operation. This includes keeping input traces short, separating analog and digital grounds when necessary, and providing adequate power supply routing.

Reliability and Quality

The LM239N is manufactured under strict quality control procedures to ensure high reliability. Key reliability characteristics include:

• ESD Protection: All inputs and outputs protected to 2000V (Human Body Model)
• Moisture Sensitivity Level (MSL): MSL 1 (Unlimited floor life at ≤30°C/85% RH)
• Lead Finish: Matte Tin (100% Sn)
• RoHS Compliance: Compliant with Directive 2011/65/EU