LM35 Temperature Sensor

Wiring Connections:

• Pin 1 (Vcc): Power supply pin; connect to a voltage source ( between 4V and 30V).
• Pin 2 (Vout): Analog output pin; provides the temperature reading in the form of voltage.
• Pin 3 (GND): Ground pin; connect to the ground of your power supply.

For typical setups:

• Vcc connects to 5V (for Arduino) or 3.3V (for ESP32).
• Vout connects to an analog input pin on your microcontroller.
• GND connects to the ground of the microcontroller.

Power:

• Supply Voltage: The sensor operates within a voltage range of 4V to 30V,  5V.
• Power Consumption: Consumes a very low current (approximately 60µA), suitable for low-power applications.

Input and Output:

• Input: Requires a DC power supply in the range of 4V to 30V.
• Output: Provides an analog voltage output that is linearly proportional to the temperature. The voltage increases by 10 mV for every degree Celsius increase in temperature. For example:
  • 0°C = 0V
  • 25°C = 250mV
  • 100°C = 1,000mV (1V)

Physical Characteristics:

• Size: Compact TO-92 package, which is a small transistor-like form factor.
• Pins: Three pins for easy connectivity to breadboards, microcontrollers, and development boards.
• Weight: Very lightweight,  less than 1 gram.
• Material: Encased in plastic or metal, depending on the package type (TO-92 being plastic).

Technical Specifications:

• Temperature Sensing Range: -55°C to 150°C
• Accuracy: ±0.5°C at 25°C, with slightly less accuracy at higher or lower temperatures.
• Output Voltage: 10 mV per degree Celsius.
• Response Time:  responds to temperature changes within a few milliseconds.
• Thermal Resistance: The sensor has low thermal resistance, which ensures quick response to temperature variations.

Additional Features:

• Linear and Calibrated: The linear output simplifies calculations, and no external calibration is needed, making it easier to work with.
• Wide Compatibility: Can be easily integrated with Arduino, Raspberry Pi, ESP32, or any microcontroller with an analog input pin.
• Cost-Effective: An affordable temperature sensor with great accuracy and reliability.

How to Use:

• Connecting the LM35:
  • Connect Pin 1 (Vcc) to a 5V (or 3.3V) power source.
  • Connect Pin 2 (Vout) to an analog input pin on your microcontroller (e.g., A0 on Arduino).
  • Connect Pin 3 (GND) to the ground (GND) of your circuit.
• Reading Temperature with Arduino:
  • Code Example:

cpp

Copy code

int sensorPin = A0;  // Analog input pin for LM35

float temperatureC;

void setup() {

Serial.begin(9600);

}

void loop() {

int sensorValue = analogRead(sensorPin);  // Read analog voltage

temperatureC = (sensorValue * 5.0 * 100.0) / 1024;  // Convert voltage to temperature

Serial.print(“Temperature: “);

Serial.print(temperatureC);

Serial.println(” °C”);

delay(1000);  // Wait a second between readings

}

• • In this code, you can read the analog value from the sensor, convert it to temperature, and print it to the serial monitor.
• Calculating Temperature:
  • Since the LM35 gives 10 mV for every 1°C, you can calculate the temperature in °C by using the formula:
    1. Temperature (°C) = Vout / 10mV
  • For example, if the sensor outputs 250 mV, the temperature is 25°C.
• Measuring Temperature with Raspberry Pi:
  • You will need an ADC (Analog-to-Digital Converter) to interface the LM35 with a Raspberry Pi, as the Pi doesn’t have built-in analog inputs.
  • Use an ADC module like MCP3008 to convert the analog signal from LM35 to digital.
• Applications:
  • Temperature Monitoring: Use it to monitor temperature in various environments, including homes, industrial sites, and weather stations.
  • Thermostats: Can be used in thermostat systems to regulate heating and cooling devices based on temperature readings.
  • DIY Projects: Ideal for hobbyist projects that involve temperature sensing, such as smart fans or weather stations.
  • Medical Devices: Suitable for non-critical medical devices that require precise temperature monitoring.
  • HVAC Systems: Commonly used to measure ambient temperature and control heating, ventilation, and air conditioning systems.

The LM35 Temperature Sensor is a precise, linear-output device for measuring temperature in the range of -55°C to 150°C. Its low cost, ease of use, and compatibility with microcontrollers make it perfect for various DIY electronics and professional applications. With simple analog output and reliable performance, this sensor is widely used in projects requiring accurate temperature measurement.