Introduction

The LM35DZ is a precision integrated-circuit temperature sensor that provides an analog output voltage linearly proportional to the Celsius temperature. With ±0.5°C accuracy (at 25°C) and no external calibration required, it’s ideal for environmental monitoring, HVAC systems, and industrial applications.

Key Features

Technical Specifications

Pin Configuration (TO-92 Package)

Pin	Name	Description	Arduino Connection
1	VCC	Power Supply (4-30V)	5V
2	VOUT	Analog Output	A0
3	GND	Ground	GND

Basic Wiring (Arduino)

// Basic Connections:
// VCC → 5V
// VOUT → A0 (or any analog input)
// GND → GND

// Optional: Add 0.1μF capacitor between VCC and GND
// for noise reduction in electrically noisy environments

Temperature Measurement Example

const int sensorPin = A0;

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

void loop() {
  // Read analog voltage (0-1023)
  int sensorValue = analogRead(sensorPin);
  
  // Convert to voltage (5V reference)
  float voltage = sensorValue * (5.0 / 1023.0);
  
  // Convert to temperature (10mV per °C)
  float temperature = voltage * 100;
  
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  
  delay(1000);
}

Advanced Applications

// For -55°C to +150°C range:
// Use LM35CZ version with dual supply
// Connect VCC to +5V, GND to -5V
// Output will be 0V at 0°C, positive for
// temperatures above zero, negative below

// Use Arduino's internal 1.1V reference
analogReference(INTERNAL); // 1.1V on ATmega
// Now 1.1V = 1023, giving ~0.1°C resolution
// in the 0-110°C range

// Array of sensor pins
const int sensorPins[] = {A0,A1,A2,A3};
float temperatures[4];

void readTemperatures() {
  for(int i=0; i<4; i++) {
    int val = analogRead(sensorPins[i]);
    temperatures[i] = (val * (5.0/1023.0)) * 100;
  }
}

// Moving average filter
#define READINGS 10
float tempHistory[READINGS];
int index = 0;

float getFilteredTemp() {
  tempHistory[index] = temperature;
  index = (index + 1) % READINGS;
  
  float sum = 0;
  for(int i=0; i