Complete LM35 Temperature Sensor Datasheet Guide

The LM35 temperature sensor is a widely used precision analog device designed to provide accurate and linear temperature measurements directly in degrees Celsius. This article will discuss the LM35 temperature sensor in detail, including its pinout, specifications, features, functional block diagram, application circuits, and more.

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LM35 Temperature Sensor Overview

The LM35 temperature sensor is a precision integrated-circuit device designed to measure temperature accurately and efficiently. Its output voltage changes linearly with temperature in degrees Celsius, which makes temperature readings simple and direct. Since the sensor is factory-calibrated, it does not require additional calibration or complex signal processing, reducing design effort in electronic systems.

One of the key advantages of the LM35 is its low output impedance and minimal self-heating, allowing it to deliver stable and reliable readings even during continuous operation. It operates with single or dual power supplies and supports a wide temperature range, making it suitable for both industrial and consumer applications. The sensor is available in multiple package options, which helps designers integrate it easily into different circuit layouts.

If you are interested in purchasing the LM35 temperature sensor, feel free to contact us for pricing and availability.

LM35 Temperature Sensor CAD Models

LM35 Temperature Sensor Pinout Details

Alternatives & Equivalent Model

Model	Type	Output	Temperature Range	Accuracy	Notes
LM34	Analog IC	10 mV/°F	0°C to 100°C	±1°F	Output in Fahrenheit scale
LM36	Analog IC	10 mV/°C	−40°C to 125°C	±2°C	Better for low-temperature sensing
TMP36 TMP36 In Stock: 500 pcs	Analog IC	10 mV/°C	−40°C to 125°C	±2°C	Does not require negative supply
DS18B20 DS18B20 UMW 11 B -55 ~ 125C 1-WIRE DIGITAL, In Stock: 23265 pcs	Digital	Digital (1-Wire)	−55°C to 125°C	±0.5°C	High accuracy, digital interface
DHT11	Digital	Digital	0°C to 50°C	±2°C	Measures temperature & humidity
DHT22	Digital	Digital	−40°C to 80°C	±0.5°C	Higher accuracy than DHT11
MCP9700 MCP9700 Microchip In Stock: 2100 pcs	Analog IC	10 mV/°C	−40°C to 125°C	±2°C	Low-power temperature sensor

LM35 Functional Block Diagram

The LM35 block diagram shows how temperature is converted into a precise voltage output inside the sensor. At the core of the circuit is a temperature-sensing element based on transistor junction behavior, which generates a voltage that changes predictably with temperature. This internal reference produces a small temperature-dependent signal that forms the basis of the measurement.

This signal is first processed by an internal amplifier stage that stabilizes and conditions it. The diagram shows how the sensor uses matched transistors and resistors to create a voltage that increases linearly as temperature rises. This design helps ensure good accuracy and consistency across the operating range.

Finally, the conditioned signal is fed into an output amplifier that scales it to a usable level. This stage produces the familiar LM35 output of 10 mV per degree Celsius at the VOUT pin. The output stage also provides low output impedance, making the sensor easy to connect directly to microcontrollers, ADCs, or measurement circuits without additional signal conditioning.

LM35 Temperature Sensor Specifications

LM35 Temperature Sensor Features

Calibrated Directly in Celsius (Centigrade)

The LM35 provides an output voltage that directly corresponds to temperature in degrees Celsius, removing the need for unit conversion from Kelvin or Fahrenheit.

Linear 10 mV/°C Scale Factor

The output increases by 10 millivolts for every 1°C rise in temperature, making temperature calculations simple and predictable.

0.5°C Ensured Accuracy at 25°C

The sensor delivers reliable readings around room temperature, which is important for indoor, laboratory, and electronic monitoring applications.

Rated for Full −55°C to +150°C Temperature Range

The LM35 can operate across a wide temperature range, allowing it to be used in both low-temperature and high-temperature environments.

Suitable for Remote Applications

Its low output impedance and stable signal allow accurate temperature measurement even when the sensor is located far from the readout or control circuit.

Low Cost Due to Wafer-Level Trimming

Factory calibration during manufacturing eliminates the need for external trimming components, reducing overall system cost.

Operates from 4 V to 30 V Supply

The wide operating voltage range makes the LM35 compatible with many power sources, including batteries and regulated power supplies.

Less Than 60 µA Current Drain

Very low power consumption helps minimize energy usage and makes the sensor suitable for low-power and battery-operated systems.

Low Self-Heating (0.08°C in Still Air)

Minimal internal heat generation ensures that the sensor does not significantly affect its own temperature readings.

Low Non-Linearity (±0.25°C Typical)

The sensor maintains a highly linear response over its operating range, which improves measurement accuracy.

Low-Impedance Output (0.1 Ω for 1 mA Load)

A low output impedance allows the LM35 to drive ADC inputs and signal lines directly without additional buffering circuits.

LM35 Typical Application Circuits

The basic centigrade temperature sensor circuit shows the LM35 connected using a single positive power supply. In this configuration, the sensor directly outputs an analog voltage that increases linearly with temperature at a rate of 10 mV per degree Celsius. Since the output starts at 0 mV near 0°C, this setup is well suited for temperature measurements above freezing. Its simple wiring makes it ideal for general-purpose monitoring, microcontroller projects, and applications that only require positive temperature readings.

The full-range centigrade temperature sensor circuit demonstrates how the LM35 can measure temperatures below 0°C by using both positive and negative supply voltages. The added resistor connected to the negative supply allows the output to shift, enabling accurate sensing across the full temperature range. This configuration is useful in environments where temperatures may drop below freezing and more complete temperature coverage is required.

LM35 Temperature Sensor Applications

• Ambient temperature monitoring

• Microcontroller-based projects

• Weather monitoring systems

• Industrial temperature control

• Power supply and heat sink monitoring

• Consumer electronics

• Battery and charger temperature monitoring

• HVAC systems

• Medical and health equipment

• Educational and training kits

Comparison: LM35 Sensor vs LM335

Parameter	LM35 Temperature Sensor	LM335 LM335 ST LM335 ST In Stock: 2970 pcs Temperature Sensor
Temperature Measurement Scale	Celsius (°C)	Kelvin (K)
Output Type	Analog voltage	Analog voltage
Output Sensitivity	10 mV/°C	10 mV/K
Output at 25°C	250 mV	~2.98 V (298 K)
Operating Temperature Range	−55°C to +150°C	−40°C to +100°C
Accuracy at 25°C	±0.25°C (typical)	±1°C (typical, uncalibrated)
Accuracy Over Full Range	±0.75°C (typical)	±2°C (typical)
Calibration	Factory calibrated in °C	Requires external calibration
External Trimming	Not required	Required for best accuracy
Supply Voltage Range	4 V to 30 V	4 V to 30 V
Supply Current	~60 µA	~400 µA
Self-Heating	< 0.1°C in still air	Higher than LM35
Output Impedance	Low (~0.1–0.5 Ω)	Higher than LM35
Output Linearity	High (±0.25°C typical)	Moderate
Ease of Interface	Very easy (direct °C reading)	Requires Kelvin-to-Celsius conversion
Typical Packages	TO-92, TO-220, SOIC, TO-CAN	TO-92, TO-220
Cost	Slightly higher	Lower
Common Applications	Precision temperature sensing, MCUs	Basic temperature sensing, calibration circuits

Mechanical Dimensions

The LM35 temperature sensor is offered in multiple package options to suit different design and mounting requirements. It is available in four package types, including TO-92, TO-220, TO-CAN (metal can), and SOIC. Each package provides the same electrical performance while allowing flexibility for prototyping, industrial use, or compact PCB layouts. Below is the TO-92 package suitable for space-constrained and surface-mount applications.

Manufacturer

Texas Instruments has strong manufacturing capability in producing the LM35 temperature sensor, supported by decades of expertise in analog and mixed-signal semiconductor design. TI designs and fabricates the LM35 using precise wafer-level trimming and calibration techniques, ensuring consistent accuracy, linearity, and reliability without the need for external adjustment. Its global semiconductor manufacturing, packaging, and quality-control infrastructure allows the LM35 to be offered in multiple package options while meeting strict industrial and commercial standards.

Conclusion

The LM35 temperature sensor is easy-to-use solution for precise temperature measurement in Celsius-based systems. Its linear 10 mV/°C output, low self-heating, factory calibration, and wide supply voltage range simplify circuit design while maintaining dependable accuracy. Through its specifications, features, application circuits, and comparison with alternatives such as the LM335 LM335 ST LM335 ST In Stock: 2970 pcs , the LM35 proves suitable for a broad range of monitoring and control tasks.

Frequently Asked Questions [FAQ]

1. How to calculate temperature from the LM35 output voltage?

To calculate temperature, divide the LM35 output voltage (in millivolts) by 10. For example, 320 mV corresponds to 32°C.

2. Can the LM35 be used without a microcontroller?

Yes, the LM35 can be used with analog meters, comparators, or operational amplifiers to display or control temperature without a microcontroller.

3. Does the LM35 need a heatsink for accurate readings?

No, the LM35 does not require a heatsink under normal conditions due to its very low self-heating during operation.

4. Can the LM35 measure temperature below 0°C?

Yes, but measuring below 0°C requires a dual power supply or a circuit offset to shift the output voltage.

5. Is the LM35 waterproof or suitable for outdoor use?

No, the LM35 is not waterproof by default and must be enclosed or protected for outdoor or high-humidity environments.

6. What causes inaccurate LM35 temperature readings?

Common causes include electrical noise, long unshielded wires, poor grounding, and insufficient power supply filtering.

7. Can multiple LM35 sensors be used in one system?

Yes, multiple LM35 sensors can be used together, provided each sensor has proper wiring and separate ADC channels if needed.