LM339DR2G Quad Differential Comparator: Datasheet, Application Circuit, and Pinout Configuration

The LM339DR2G is a highly versatile, industry-standard integrated circuit from ON Semiconductor, belonging to a family of quad independent precision voltage comparators. Each of the four comparators within the single package is designed to operate from a single power supply over a wide range of voltages or from dual supplies, making it an essential component for a vast array of analog and digital systems.

This article delves into the key specifications of the LM339DR2G, a typical application circuit, and its pin configuration to provide a comprehensive understanding of its functionality and implementation.

Datasheet Overview and Key Specifications

The LM339DR2G datasheet provides all the necessary electrical characteristics and operational parameters. Key specifications that define its performance include:

Wide Supply Voltage Range: It can operate from a single supply voltage as low as 2V up to 36V, or from dual supplies of ±1V to ±18V. This flexibility is crucial for both battery-powered and line-operated equipment.

Low Supply Current Drain: The device is very efficient, with a low supply current of approximately 0.8mA, which is independent of the supply voltage. This makes it ideal for portable and power-sensitive applications.

Low Input Bias Current: The input bias current is typically 25nA, which minimizes the loading effect on the input signal source.

Low Input Offset Voltage: A typical offset voltage of 2mV ensures accurate comparison thresholds.

Common-Mode Input Voltage Range: Includes ground (0V), even when operating from a single supply, allowing it to sense signals at or below the negative rail.

Output Type: The output is an open-collector configuration. This allows the output to be easily wired-OR connected with other outputs and to interface directly with a wide range of digital logic families (e.g., TTL, CMOS, etc.) by simply connecting a pull-up resistor to the desired logic voltage rail.

Pinout Configuration

The LM339DR2G is offered in a standard SOIC-14 surface-mount package. The pinout is arranged as follows:

Pins 2, 4, 6, 8 (Inputs -): The inverting inputs for comparators 1, 2, 3, and 4, respectively.

Pins 3, 5, 7, 9 (Inputs +): The non-inverting inputs for comparators 1, 2, 3, and 4, respectively.

Pins 1, 14, 13, 12 (Outputs): The open-collector outputs for comparators 1, 2, 3, and 4, respectively.

Pin 11 (GND): Ground (Negative Supply).

Pin 10 (VCC+): Positive Supply Voltage.

A Classic Application Circuit: Light Level Detector

A fundamental application of the LM339DR2G is a light-sensitive switch. One of its four comparators can be configured as follows:

1. Components: One comparator of the LM339DR2G, a photoresistor (LDR), a fixed resistor (forming a voltage divider), a pull-up resistor at the output, and an LED with a current-limiting resistor.

2. Configuration: The non-inverting input (+) is connected to a reference voltage created by a potentiometer or a fixed resistor divider. The inverting input (-) is connected to the node between the photoresistor and another resistor forming a light-sensitive voltage divider.

3. Operation: As the light level changes, the resistance of the LDR changes, altering the voltage at the inverting input. When the voltage at the inverting input falls below the reference voltage set at the non-inverting input, the comparator output switches from high-impedance (off) to active low (sinking current), turning on the LED. This simple circuit effectively detects a predefined light threshold.

This same principle can be extended to temperature control using a thermistor, voltage monitoring, zero-crossing detectors, and more complex systems like oscillators and analog-to-digital converters.

ICGOODFIND: The LM339DR2G stands as a fundamental building block in electronic design, prized for its robust performance, simplicity, and extreme versatility. Its ability to operate from a wide range of supply voltages, including single-supply with ground sensing, combined with its open-collector outputs, makes it an indispensable tool for designers for signal conditioning, threshold detection, and interfacing between analog and digital worlds.

Keywords:

1. Comparator

2. Open-Collector

3. Single-Supply

4. Voltage Comparison

5. Threshold Detection