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Mastering temperature sensing: A comprehensive LM35 guide


Temperature sensing is integral across diverse electronic applications, from environmental monitoring to industrial control systems. The LM35 emerges as a favored option for its simplicity, accuracy, and user-friendly nature. This guide delves into the LM35 sensor, covering its features, working principle, applications, and practical considerations. With its linear output proportional to temperature, ranging from -55°C to +150°C, the LM35 offers precise readings. Its compatibility with microcontrollers further enhances its utility, facilitating integration into digital systems. From weather stations to medical devices, the LM35 finds versatile application, underlining its significance in modern electronics. Understanding its nuances empowers engineers and hobbyists to harness its capabilities effectively.

Overview of the LM35 temperature sensor

The LM35 is a precision integrated-circuit temperature sensor whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. Manufactured by Texas Instruments, the LM35 is widely used in various industries and hobbyist projects owing to its reliability and straightforward operation.

Working principle

The LM35 operates on the principle of the voltage output proportional to temperature. It converts temperature directly into electrical voltage, with a linear output of 10 mV per degree Celsius. For instance, at 25°C, the output voltage would be 250 mV.

Features of the LM35

Wide temperature range: The LM35 can measure temperatures ranging from -55°C to +150°C, making it suitable for diverse applications.

  • High accuracy: With a typical accuracy of ±0.5°C at room temperature, the LM35 provides precise temperature measurements.
  • Low self-heating: The sensor exhibits minimal self-heating, ensuring accurate readings even in extended operation.
  • Low cost and easy availability: The LM35 is an economical solution readily available in the market.

Pin configuration

The LM35 comes in a small three-lead TO-92 package. Its pin configuration includes:

  • Pin 1: Output (provides the temperature-dependent voltage output)
  • Pin 2: Vcc (connected to the positive supply voltage)
  • Pin 3: Ground (connected to the ground/reference voltage)

Interfacing with microcontrollers

One of the LM35’s advantages is its compatibility with microcontrollers, making it ideal for integration into digital systems. By connecting the output pin to an analog input of a microcontroller (such as Arduino), temperature readings can be easily acquired and processed.

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Applications of the LM35

The LM35 finds applications in various fields, including:

  • Environmental monitoring: Monitoring temperature in weather stations, greenhouses, and HVAC systems.
  • Industrial automation: Controlling temperature in manufacturing processes, storage facilities, and equipment.
  • Medical devices: Monitoring body temperature in thermometers and medical equipment.
  • Consumer electronics: Temperature measurement in appliances, computers, and automotive systems.

 Practical considerations

When using the LM35, several factors should be considered:

  • Calibration: While the LM35 offers good accuracy out of the box, calibration may be necessary for critical applications requiring higher precision.
  • Noise and interference: Shielding the sensor from electromagnetic interference and minimizing noise in the circuitry is essential for accurate readings.
  • Power supply: Ensure a stable and noise-free power supply to the LM35 to prevent fluctuations in temperature readings.


The LM35 temperature sensor is a versatile and reliable component widely used for temperature measurement in diverse applications. Its simplicity, accuracy, and ease of integration make it a preferred choice for engineers, hobbyists, and enthusiasts alike. Understanding the LM35’s features, working principle, and practical considerations is essential for leveraging its full potential in electronic designs and projects.

In summary, the LM35 stands as a testament to the efficacy of integrated circuit technology in simplifying complex tasks, providing precise temperature sensing capabilities in a compact and affordable package.

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