TMP36 vs LM35: Analog Temperature Sensor for Arduino

When you need a simple analog temperature sensor for an Arduino project, two names always come up: the LM35 and the TMP36. Both are inexpensive, 3-pin analog sensors that output a voltage proportional to temperature. But they differ in their output formulas, supply voltage requirements, and temperature range — and choosing the wrong one for your circuit can produce completely incorrect readings.

This guide provides a thorough TMP36 vs LM35 comparison with exact formulas, wiring diagrams, and Arduino code for both sensors so you can make the right choice and measure temperature correctly from day one.

What Are TMP36 and LM35?

Both sensors are analog integrated circuit temperature sensors — meaning they produce a DC voltage output that varies linearly with temperature, with no digital conversion needed. Connect power and ground, read the voltage with an ADC (like Arduino’s built-in 10-bit ADC), apply a formula, and you have a temperature reading.

• The LM35 is made by Texas Instruments (originally National Semiconductor). It has been in production since the 1970s and remains popular in educational and industrial settings.
• The TMP36 is made by Analog Devices. It has a wider supply voltage range (2.7–5.5 V vs LM35’s 4–30 V) and can measure negative temperatures with a single supply.

Both come in standard TO-92 (plastic transistor) packages with three pins, making them look almost identical. Read the markings carefully — they are not pin-compatible and produce different output voltages for the same temperature.

LM35 Specifications and Output Formula

LM35 Output Equation

Vout = 10 mV/°C × Temperature (°C)

Examples:
  At 0°C:   Vout = 0.000 V
  At 25°C:  Vout = 0.250 V
  At 100°C: Vout = 1.000 V

The LM35 outputs exactly 0 V at 0°C, which seems intuitive, but it creates a problem: you cannot measure negative temperatures with a standard single-supply circuit. To measure below 0°C, the output would need to go negative, which a standard ADC cannot read.

LM35 Key Specifications

LM35 Variants

• LM35A: ±1°C accuracy over full −55°C to +150°C range
• LM35C/CA: Rated for −40°C to +110°C range
• LM35D/DZ: 0°C to +100°C range only, lower cost

For Arduino projects, the common LM35DZ (0–100°C range) is the most affordable and readily available variant.

LM35 Temperature Sensors

Classic 10 mV/°C analog output temperature sensor. Ideal for Arduino temperature monitoring, HVAC, and learning projects. Easy to use.

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TMP36 Specifications and Output Formula

TMP36 Output Equation

Vout = 500 mV + (10 mV/°C × Temperature)

Or rearranged to find temperature:
Temperature (°C) = (Vout_mV − 500) / 10

Examples:
  At −40°C: Vout = 0.100 V
  At 0°C:   Vout = 0.500 V
  At 25°C:  Vout = 0.750 V
  At 100°C: Vout = 1.500 V

The TMP36 includes a 500 mV offset at 0°C. This is the key difference from the LM35. The offset means the output at room temperature is around 0.75 V — well within the ADC measurement range — and even at −40°C, the output is still 0.1 V (positive), so negative temperatures can be measured with a standard single-supply circuit.

TMP36 Key Specifications

Side-by-Side Comparison Table

Wiring Both Sensors to Arduino

LM35 Pinout (TO-92 package, flat face toward you)

    LM35 TO-92 (flat face)
    ┌───────────────┐
    │  VCC  OUT  GND│
    │  (1)  (2)  (3)│
    └───────────────┘

VCC (Pin 1) → 5V (must be ≥4V)
OUT (Pin 2) → Arduino A0
GND (Pin 3) → GND

Add 100nF bypass cap between VCC and GND (close to the sensor)

TMP36 Pinout (TO-92 package, flat face toward you)

    TMP36 TO-92 (flat face)
    ┌───────────────┐
    │  VCC  OUT  GND│
    │  (1)  (2)  (3)│
    └───────────────┘

VCC (Pin 1) → 3.3V or 5V
OUT (Pin 2) → Arduino A0
GND (Pin 3) → GND

Note: LM35 and TMP36 look IDENTICAL but have different output formulas!

Important: The LM35 and TMP36 have the same physical pin arrangement — but their output voltages for a given temperature are completely different. Always double-check the IC marking on the package before connecting.

Arduino Code: LM35

// LM35 Temperature Sensor - Arduino Code
// Power sensor from 5V. Connect output to A0.

const int LM35_PIN = A0;
const float VREF = 5.0;           // Arduino reference voltage
const int ADC_RESOLUTION = 1023;  // 10-bit ADC

void setup() {
  Serial.begin(9600);
  Serial.println("LM35 Temperature Sensor");
}

void loop() {
  // Average 10 readings to reduce noise
  long sum = 0;
  for (int i = 0; i < 10; i++) {
    sum += analogRead(LM35_PIN);
    delay(10);
  }
  int rawValue = sum / 10;

  // Convert ADC reading to voltage
  float voltage = rawValue * (VREF / ADC_RESOLUTION);

  // LM35 formula: Temp (°C) = Voltage (mV) / 10
  float temperature_C = (voltage * 1000.0) / 10.0;
  float temperature_F = (temperature_C * 9.0 / 5.0) + 32.0;

  Serial.print("Raw ADC: "); Serial.print(rawValue);
  Serial.print(" | Voltage: "); Serial.print(voltage, 3); Serial.print(" V");
  Serial.print(" | Temp: "); Serial.print(temperature_C, 1); Serial.print(" C");
  Serial.print(" / "); Serial.print(temperature_F, 1); Serial.println(" F");

  delay(1000);
}

Arduino Code: TMP36

// TMP36 Temperature Sensor - Arduino Code
// Works with 3.3V or 5V supply. Connect output to A0.

const int TMP36_PIN = A0;
const float VREF = 5.0;  // Change to 3.3 if using 3.3V supply

void setup() {
  Serial.begin(9600);
  Serial.println("TMP36 Temperature Sensor");
}

void loop() {
  // Average 10 readings
  long sum = 0;
  for (int i = 0; i < 10; i++) {
    sum += analogRead(TMP36_PIN);
    delay(10);
  }
  float rawValue = sum / 10.0;

  // Convert to voltage
  float voltage = rawValue * (VREF / 1023.0);

  // TMP36 formula: Temp (°C) = (Voltage_mV - 500) / 10
  float temperature_C = (voltage * 1000.0 - 500.0) / 10.0;
  float temperature_F = (temperature_C * 9.0 / 5.0) + 32.0;

  Serial.print("Voltage: "); Serial.print(voltage, 3); Serial.print(" V");
  Serial.print(" | Temp: "); Serial.print(temperature_C, 1); Serial.print(" C");
  Serial.print(" / "); Serial.print(temperature_F, 1); Serial.println(" F");

  delay(1000);
}

Improving Accuracy with AREF

The biggest source of error for both sensors on Arduino is ADC reference voltage instability. The Arduino’s 5V rail varies with USB voltage and current draw — often ranging from 4.9 V to 5.1 V. Since the temperature formula divides by VREF, a 2% variation in VREF causes a 2% error in temperature (about 0.5°C at 25°C).

Two ways to improve this:

Method 1: Use Internal 1.1V Reference

Arduino has a built-in 1.1 V precision reference. For LM35 measuring 0–100°C (output 0–1.0 V), this is a perfect match:

void setup() {
  analogReference(INTERNAL); // 1.1V internal reference
  // ... rest of setup
}

// In loop, use VREF = 1.1:
float voltage = rawValue * (1.1 / 1023.0);
float temp_C  = (voltage * 1000.0) / 10.0; // LM35

Caution: Do NOT connect the sensor output to the AREF pin when using INTERNAL reference.

Method 2: Use External Precision Reference

For the highest accuracy, connect a precision 3.3 V or 2.5 V voltage reference (e.g., LM4040, REF3033) to the AREF pin and call analogReference(EXTERNAL). This eliminates VREF instability entirely.

Measuring Negative Temperatures with LM35

The standard LM35 circuit cannot measure below 0°C with a single supply because the output goes to 0 V at 0°C and cannot go negative. Two solutions:

Solution 1: Use a small pull-down resistor

Connect a 18 kΩ resistor between the sensor output pin and −5 V (or −15 V if available). This shifts the output so that 0°C corresponds to a positive voltage. Requires a dual-supply (±5V) power source — not practical for most Arduino projects.

Solution 2: Switch to TMP36

If you need to measure below 0°C with a single supply, simply use the TMP36 instead. Its 500 mV offset at 0°C means the output stays positive down to −40°C (output = 0.1 V at −40°C), readable by any standard ADC.

Which Sensor Should You Choose?

Choose LM35 when:

• You only need to measure temperatures from 0°C to 100°C (indoor environments, body temperature, electronics monitoring)
• You want the simplest possible formula (Voltage in mV ÷ 10 = °C with no offset subtraction)
• You need better specified accuracy out of the box (±0.5°C vs TMP36’s ±2°C typical)
• You have an existing 5V-powered Arduino project
• Availability is a priority — LM35 is extremely common in India

Choose TMP36 when:

• You need to measure below 0°C (cold storage, outdoor winter monitoring, refrigeration)
• You are using a 3.3V microcontroller (ESP32, ESP8266, STM32, Raspberry Pi) — the TMP36 works from 2.7V
• You are designing a low-power battery device (TMP36 draws slightly less quiescent current)
• You need the extended range up to 125°C

Digital Alternatives to Consider

While LM35 and TMP36 are easy to use, digital temperature sensors offer several advantages: they are immune to ADC noise, can be placed far from the microcontroller without signal degradation, and often have better specified accuracy.

DS18B20 Programmable Resolution Digital Temperature Sensor

1-Wire digital sensor with ±0.5°C accuracy, 9–12 bit resolution, and −55°C to +125°C range. Multiple sensors share one Arduino pin.

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DHT11 Digital Temperature and Humidity Sensor Module

Measures both temperature and relative humidity digitally. ±2°C accuracy. Perfect for weather stations and home automation projects.

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GY-BME280-5V Temperature and Humidity Sensor

Advanced I2C/SPI sensor for temperature, humidity, and pressure. ±1°C accuracy. Ideal for professional weather stations and IoT projects.

View on Zbotic

Quick Digital Sensor Comparison

Frequently Asked Questions

Conclusion

Both the LM35 and TMP36 are excellent introductory temperature sensors that work reliably with Arduino when the correct formula and supply voltage are used. The LM35 wins on accuracy and simplicity for 0–100°C indoor applications with a 5 V supply. The TMP36 wins for battery-powered 3.3 V designs and applications requiring sub-zero temperature measurement.

For most hobbyist and educational projects measuring room temperature, either sensor will work well with basic averaging and the correct formula. When you need better accuracy, longer cable runs, or humidity measurement alongside temperature, step up to a digital sensor like the DS18B20, DHT22, or BME280.