Arduino Temperature Sensor Using LM35

Introduction

The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly proportional to the Centigrade temperature. LM35 is three terminal linear temperature sensor from National semiconductors. It can measure temperature from -55 degree Celsius to +150 degree Celsius. The voltage output of the LM35 increases 10mV per degree Celsius rise in temperature. LM35 can be operated from a 5V supply and the stand by current is less than 60uA. The pin out of LM35 is shown in the figure below.

Features

• Calibrated Directly in Celsius (Centigrade)

• Linear + 10-mV/°C Scale Factor

• 0.5°C Ensured Accuracy (at 25°C)

• Rated for Full −55°C to 150°C Range

• Suitable for Remote Applications

• Low-Cost Due to Wafer-Level Trimming

• Operates from 4 V to 30 V

• Less than 60-μA Current Drain

• Low Self-Heating, 0.08°C in Still Air

• Non-Linearity Only ±¼°C Typical

• Low-Impedance Output, 0.1 Ω for 1-mA Load PinOuts Of LM35 is Shown in image.

You can download the datasheet from below file.

• Arduino Board (Any) Buy it from Flipkart
• LM35 Sensor Buy it from Flipkart
• BreadBoard

Connect the Circuit as shown in image and upload the following code.

Download the code here

/*Code Designed by Sujay in SA Lab*/
const int sensor=A5; // Assigning analog pin A5 to variable 'sensor'
float tempc; //variable to store temperature in degree Celsius
float tempf; //variable to store temperature in Fahreinheit
float vout; //temporary variable to hold sensor reading
void setup() {
pinMode(sensor,INPUT); // Configuring sensor pin as input
Serial.begin(9600);
}
void loop() {
vout=analogRead(sensor);
vout=(vout*500)/1023;
tempc=vout; // Storing value in Degree Celsius
tempf=(vout*1.8)+32; // Converting to Fahrenheit
Serial.print("in DegreeC=");
Serial.print("\t");
Serial.print(tempc);
Serial.print(" ");
Serial.print("in Fahrenheit=");
Serial.print("\t");
Serial.print(tempf);
Serial.println();
delay(500); //Delay of 1 second for ease of viewing
}

See the result on Serial Monitor....

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