Temperature Sensor LM35

The LM35 is a popular analog temperature sensor used to measure temperature in degrees Celsius (°C). It is a versatile and affordable component that is commonly used in various electronics projects and applications such as weather stations, climate control systems, and other temperature-monitoring devices.

Key Features of LM35:

1. Output Voltage: The LM35 produces an analog voltage that is directly proportional to the temperature. The output voltage increases by 10 mV per degree Celsius rise in temperature. For example:

• At 25°C, the output will be 250 mV (0.25 V).
• At 30°C, the output will be 300 mV (0.3 V).
• At 0°C, the output will be 0 V.

1. Operating Range: The LM35 operates over a wide range of temperatures, typically from -55°C to +150°C, but the most common operating range is from 0°C to +100°C.
2. Accuracy: The LM35 has a high accuracy with a tolerance of about ±0.5°C at room temperature.
3. Low Power Consumption: The LM35 is designed to operate at very low power levels, making it suitable for battery-powered applications.
4. Linear Output: The output voltage is linear with respect to the temperature, making it easy to interface with analog-to-digital converters (ADC) in microcontrollers for further processing.
5. Simple Interface: It only requires a power supply (usually 5V) and ground, along with the output signal being read by an ADC.

Typical Circuit with LM35

• Power Supply: Typically 5V (can also be 3.3V in some cases)
• GND: Connected to the ground (0V)
• Vout: The analog output voltage which is directly related to the temperature.

Example Circuit:

1. LM35 Pinout:

• Pin 1 (Vcc): Supply voltage (typically 5V)
• Pin 2 (Vout): Output voltage (proportional to the temperature)
• Pin 3 (GND): Ground pin

1. Microcontroller Interface (e.g., Arduino):

• Connect Vcc to 5V.
• Connect GND to the ground.
• Connect Vout to an analog input pin (e.g., A0 on Arduino).

Arduino Example Code:

int tempPin = A0;  // LM35 output pin connected to A0
float temperature;

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(tempPin);
  // Convert the analog reading (0-1023) to a voltage (0-5V)
  float voltage = sensorValue * (5.0 / 1023.0);
  // Convert the voltage to temperature (LM35: 10mV per degree Celsius)
  temperature = voltage * 100;  
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" C");
  delay(1000);  // Wait for a second before reading again
}

Calibration and Considerations:

• The LM35 provides an output of 10 mV per degree Celsius. However, you should calibrate it if you need extremely precise measurements. You can compare the sensor readings with a known thermometer and adjust the calculation factor if necessary.
• Make sure to avoid noise in the sensor's analog signal, as it can affect accuracy. Use proper filtering if required, especially for longer sensor cables or noisy environments.

Origin: China

Brand:- Generic