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To monitor temperature with an LM35, connect its output to an Arduino analog input, convert the analog reading to voltage using the board’s actual ADC reference and resolution, then divide the voltage by 0.010 V/°C. The LM35’s nominal output slope is 10 mV per degree Celsius; the exact wiring and achievable accuracy depend on the sensor package and the Arduino board.
What you need to know before wiring an LM35
The LM35 is an analog temperature sensor whose output voltage scales directly with Celsius temperature. Texas Instruments specifies a nominal scale factor of 10 mV/°C, so an output of 0.250 V corresponds nominally to 25°C. See the TI LM35 product page and the LM35 datasheet, Rev. H.
Before connecting anything, identify the complete part number and package. TI lists multiple package options and family members with differing temperature ranges. Use the pinout and electrical limits for your specific part rather than assuming a generic three-pin drawing matches it. The datasheet is the authority for the sensor’s pin connections and operating conditions.
- LM35 sensor, with its exact suffix and package identified.
- Arduino board with an available analog input. The example documented by Arduino uses an Uno R3.
- Breadboard and jumper wires if you are making a temporary prototype; the Arduino example lists a breadboard, while wires are a practical implementation choice.
The Arduino temperature-sensor project documentation lists a breadboard and Uno R3. Treat that as an example build, not as a universal board requirement.
#1 Best Overall
- 【Linear Analog Temperature Output】 LM35DZ analog temperature sensor module; linear voltage output scaled at 10 mV per degree Celsius; enables simple temperature reading through analog inputs; eliminates digital protocol handling; ideal for quick signal sampling in control and monitoring projects
- 【Wide Supply Voltage And Low Power】 Operating supply voltage from 4.0 V to 30 V; current consumption below 60 µA; supports stable operation across varied power systems; suitable for long‑run testing and low‑power embedded applications using analog sensing
- 【Accurate And Stable Measurement Range】 Temperature measurement range from 0 °C to 100 °C; typical accuracy ±0.5 °C at 25 °C; fast response time under 1 second; provides consistent readings for real‑time temperature monitoring and feedback control
- 【Simple Three‑Pin Interface Design】 Three‑pin layout with VCC, OUT, and GND; direct connection to MCU analog input channels; reduces wiring complexity; improves reliability during prototyping and educational circuit assembly
- 【Compact Module For Easy Integration】 Small footprint module fits breadboards and learning kits; analog output compatible with for Arduino and similar controllers; supports smart car platforms and educational electronics projects requiring straightforward temperature sensing
Connect the sensor to the Arduino
Wire the sensor’s supply, ground, and output according to the datasheet for the exact LM35 package you have. Connect the output to a valid analog input on your selected board. Do not infer pin order from package appearance: pin assignments can vary by package, and reversing supply or output connections can prevent correct operation or damage a part.
Use the Arduino board’s documented input limits and ADC configuration. The elementary hookup described here is a positive-output, single-supply measurement; it does not automatically measure the LM35 family’s full negative-temperature range.
Rank #2
- Rated for full −55˚ to +150˚C range
- Suitable for remote applications
- Operates from 4 to 30 volts
- Low self-heating, 0.08˚C in still air
- Nonlinearity only ±1⁄4˚C typical
Convert an Arduino analog reading to Celsius
First convert the ADC count to voltage using the reference voltage and resolution actually configured for your board. If the ADC produces counts from 0 through N, the nominal conversion is:
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Rank #3
- Precision Temperature Measurement: Linear 10mV/°C output (0V at 0°C) with ±0.25°C accuracy at 25°C for reliable data
- Plug-and-Play Compatibility: 3-pin interface works compatible with Microbit and most microcontroller expansion boards 5VDC powered
- Robust Design: Four 3mm mounting holes secure the module to prototypes or enclosures; compact size 34×22×9mm, 2.6g
- Wide Operating Range: Measures -40°C to +110°C, ideal for environmental monitoring, DIY projects, and industrial prototyping
- Analog Signal Output: Directly interfaces for real-time temperature logging and control systems, suitable for engineers, technicians, factories, individual DIY, electronic enthusiasts, etc
Then apply the LM35 scale factor:
Temperature (°C) = Voltage (V) ÷ 0.010
Equivalently, temperature in Celsius is the measured sensor voltage in millivolts divided by 10. These formulas assume the sensor’s nominal 10 mV/°C slope and a correct ADC reference and count range. Do not hard-code a 5 V reference or a particular ADC bit depth as if it applied to every Arduino: boards differ, and settings may be configurable. TI’s Arduino demonstration discusses ADC configuration and reducing conversion error: How to Interface the LM35 Analog Temperature Sensor with Arduino.
Example calculation
Suppose your ADC conversion, using the board’s own documented reference and resolution, yields 0.250 V at the sensor output. The nominal temperature calculation is 0.250 ÷ 0.010 = 25°C. This is an illustrative calculation, not a promised reading for a particular Arduino board or physical setup.
Rank #4
- LM35DZ Analog Temperature Sensor: Built with a domestic LM35 temperature sensor chip, this module provides reliable analog temperature measurement for Arduino projects, smart cars, and DIY electronics.
- Linear 10 mV/°C Output: Delivers a linear analog signal output with a sensitivity of +10 mV per degree Celsius, making temperature reading simple and easy to process.
- Wide 4–30V DC Operating Voltage: Supports a broad 4V to 30V DC input range, offering strong compatibility with different power supplies and embedded systems.
- Low Power & Stable Performance: Consumes less than 60 µA of current, making it suitable for battery-powered applications and low-power temperature monitoring designs.
- Compact and Practical Design: Measures 29 × 13 × 10 mm and supports a 0–100°C range with ±0.5°C accuracy, ideal for compact electronic builds, temperature control, and basic sensing applications.
Read and inspect the measurement
Have your sketch report the converted temperature through the serial monitor or a display of your choice. Because the result depends on the selected board’s ADC settings and the code’s conversion, there is no single universal ADC count or serial output to expect across Arduino models.
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A digital multimeter can be useful when troubleshooting: measure the sensor output voltage and compare the voltage-based calculation with the value reported by the sketch. This can help distinguish a sensor or wiring issue from an ADC scaling or code issue; the meter is optional, not required for the basic project.
Best Value
- The sensor comes with 4 positioning holes, which is convenient for you to fix the sensor to other devices. Converting temperature changes into electrical or other forms of output is widely used in household appliances, industrial control, environmental control and other fields.
- Its output voltage has a linear relationship with the Celsius temperature scale, the output is 0V at 0, and the output voltage increases by 10mV for every 1°C increase.
- PCB material, compact and easy to carry. Suitable for operation, learning, and development of college students, engineers, technicians, factories, DIY, electronics enthusiasts, etc.
- Dedicated temperature sensor modules to ensure that products with high reliability and excellent long term stability. This sensor is fully compatible with single chip microcomputer, and its connection port is also compatible with sensor expansion board.
- Before purchasing note that this product operates between 3.3V and 5VDC. It is a commonly used LM35 temperature sensor, mainly used for temperature detection and experiments.
Understand accuracy and sources of error
TI’s product page states that the LM35 does not require external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over the full −55°C to 150°C range. Separately, the datasheet’s basic application table lists ±0.5°C at 25°C and ±1°C from −55°C to 150°C. Those are manufacturer specifications in distinct contexts, not a guarantee that a complete Arduino assembly will achieve the same system-level accuracy.
The board’s ADC and reference, wiring, installation, and measurement conditions contribute to the final result. The LM35 also produces small analog voltages, so ADC quantization and reference accuracy can matter. If tighter agreement matters for your project, compare the assembled setup against a reliable temperature reference under the conditions where it will be used.
Measure below 0°C only with an appropriate circuit
The simple voltage-to-Celsius conversion and positive-output hookup should not be treated as a complete below-zero design. A basic single-supply circuit may not represent negative temperatures as a usable positive voltage at the Arduino input. TI’s support discussion points to a datasheet circuit that lifts the LM35 ground for negative readings; consult the relevant application circuit in the LM35 datasheet and ensure the resulting Arduino input voltage stays within the board’s limits. See also TI’s LM35 support discussion.
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Common causes of incorrect readings
- Wrong pinout: confirm the exact package and datasheet before applying power.
- Wrong ADC reference or resolution in the calculation: use the settings documented for the chosen board and configured in the sketch.
- Confusing sensor accuracy with project accuracy: manufacturer specifications do not account for every error in the board, wiring, installation, or measurement process.
- Expecting the basic circuit to read negative temperatures: use an appropriate datasheet circuit and check Arduino input limits for below-zero measurements.
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