LM35 Temperature Sensor

The LM35 is a high-precision analog temperature sensor integrated circuit (IC). It delivers an exact, linear voltage output that corresponds to the temperature in Celsius degrees.

Key Features of the LM35 Sensor

• Temperature Range: It operates from 0°C to +100°C and is calibrated from -55°C to +150°C.
• Output Voltage: The output voltage is linearly proportional to the temperature, at 10 mV/°C.
• Accuracy: It typically offers ±0.5°C accuracy at +25°C, and ±3/4°C over the full -55°C to +150°C range.
• Low Impedance Output: The LM35 has a low output impedance, enabling it to drive other devices directly without the need for additional circuitry.
• Power Supply: It operates from 4V to 30V DC, making it versatile for various applications.
• Temperature Calibration: It is factory calibrated to deliver a precise output voltage for a specific temperature range.

Applications of the LM35 Sensor

• Temperature Measurement: It is commonly used in applications that require precise temperature sensing, such as climate control systems, industrial process monitoring, and automotive applications.
• Temperature Compensation: The LM35 is often used in circuits that require temperature compensation, such as analog circuits and sensor modules.
• Portable Devices: Due to its low power consumption and compact size, it is ideal for integration into handheld and portable devices.

Example Circuit

Here is a simple example of how to connect an LM35 sensor to an Arduino for temperature measurement:

const int lm35Pin = A0;  // LM35 analog pin connected to Arduino analog input A0void setup() {
  Serial.begin(9600);    // Initialize serial communication
}void loop() {
  int sensorValue = analogRead(lm35Pin);  // Read analog input
  float voltage = sensorValue * (5.0 / 1023.0);  // Convert analog reading to voltage (assuming 5V Arduino)
  
  // Convert voltage to temperature using LM35 formula (10 mV/°C)
  float temperatureC = voltage * 100.0;  // LM35 outputs 10 mV per degree Celsius
  
  // Print temperature to serial monitor
  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.println(" °C");
  
  delay(1000);  // Delay before next reading
}

Explanation:
 

• Connect the LM35 sensor's Vout pin to Arduino's analog input pin (A0 in this example).
• In the Arduino sketch, read the analog voltage from the sensor using analogRead() function.
• Convert the analog reading to voltage using the formula (sensorValue * (5.0 / 1023.0)), assuming a 5V Arduino.
• Use the LM35 formula voltage * 100.0 to convert voltage to temperature in degrees Celsius, as the LM35 outputs 10 mV per degree Celsius.
• Print the temperature readings to the Serial Monitor.

This example demonstrates how to interface the LM35 sensor with Arduino for temperature measurement. Adjust the code as needed based on your specific setup and requirements.