LM35 is a type of commonly used temperature sensor, that can be used to measure temperature with an electrical output comparative to the temperature in (°C). It can measure temperature in a better way than thermistor.
How to interface LM35 Temperature Sensor with Arduino & demonstration.
Catalog
LM35 Overview
LM35 is a commonly used temperature sensor that shows values in the form of output voltages instead of degrees Celsius, it shows high voltage values than thermocouples and may not require the output voltage to be amplified.
The output voltage of LM35 is proportional to the temperature of Celsius. The scale factor is 0.01 V/°C. One of the most important characteristics of LM35 is that it draws only 60 microamps from its supply and has a low self-heating capacity.
LM35 temperature sensor available in a variety of packages, such as T0-46 metal transistor-like package, TO-92 plastic transistor-like package, 8-lead surface mounted SO-8 small outline package.
LM35 Pinout
|
|
LM35 Temperature Sensor |
LM35 Pinout |
Pin Number |
Pin Name |
Description |
1 |
Vcc |
Input voltage is +5V for typical applications |
2 |
Analog Out |
There will be increase in 10mV for raise of every 1°C. Can range from -1V(-55°C) to 6V(150°C) |
3 |
Ground |
Connected to ground of circuit |
LM35 Functional Block Diagram
LM35 Functional Block Diagram
LM35 Features
-
Minimum and Maximum Input Voltage is 35V and -2V respectively. Typically 5V.
-
Can measure temperature ranging from -55°C to 150°C
-
Output voltage is directly proportional (Linear) to temperature (i.e.) there will be a rise of 10mV (0.01V) for every 1°C rise in temperature.
-
±0.5°C Accuracy
-
Drain current is less than 60uA
-
Low cost temperature sensor
-
Small and hence suitable for remote applications
-
Available in TO-92, TO-220, TO-CAN and SOIC package
LM35 Parameters
Parameter |
Conditions |
Value |
Unit |
Accuracy LM35, LM 35C |
T A=+25˚C |
±0.4 |
˚C |
Accuracy, LM35D |
T A=+25˚C |
±0.6 |
˚C |
Non linearity |
T MIN≤TA≤T MAX |
±0.3 |
˚C |
Sensor Gain |
T MIN≤TA≤T MAX |
+10.0 |
mV/˚C |
Load Regulation |
T A=+25˚C |
±0.4 |
mV/mA |
Line Regulation |
T A=+25˚C |
±0.01 |
mV/V |
Quiescent Current |
V S=+5V, +25˚C |
56 |
µA |
Change of Quiescent Current |
4V≤VS≤30V |
0.2 |
µA |
Temperature Coefficient of Quiescent Current |
- |
+0.39 |
µA/˚C |
Long Term Stability T J=T MAX, for 1000 hours |
±0.08 |
±0.08 |
˚C |
LM35 Equivalents
LM35 Temperature Sensor Equivalent: LM34, DS18B20, DS1620, LM94022
LM35 Working Principle
To understand the operation of the LM35 temperature sensor, we must first understand the linear scale factor. It is stated in the LM35 specifications to be +10 millivolts per degree centigrade. It means that for every 10 millivolt increase in output from the sensor vout pin, the temperature value increases by one. For example, if the sensor outputs 100 millivolts at the vout pin, the temperature in degrees Celsius will be 10 degrees Celsius. The negative temperature reading is the same. The temperature will be -10 degrees Celsius if the sensor outputs -100 millivolts.
LM35 scale factor
How to use LM35 Temperature Sensor
LM35 is an Integrated Circuit Temperature Sensor whose output voltage varies depending on the temperature around it. It is a small and cheap IC that can be used to measure temperatures anywhere from-55°C to 150°C. It can be easily interfaced with any Microcontroller that has ADC function or any development platform like Arduino.
Power the IC by applying a regulated voltage like +5V (VS) to the input pin and connecting the ground pin to the ground of the circuit. Now, you can measure the temperature in the form of a voltage as shown below.
LM35 temperature measurement in form of voltage
If the temperature is 0°C, the output voltage will also be 0V. There will be an increase of 0.01V (10mV) for each degree of temperature increase. The voltage can be converted to temperature using the formulas below.
LM35 Applications
-
Measuring temperature of a particular environment
-
Providing thermal shutdown for a circuit/component
-
Monitoring Battery Temperature
-
Measuring Temperatures for HVAC applications.
LM35 Package
Conponent Datasheet
FAQ
The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. ... The low-output impedance, linear output, and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy.
|
- How does LM35 temperatrure sensor work?
The LM35 is an integrated circuit sensor that can be used to measure temperature with an electrical output proportional to the temperature (in °C). It can measure temperature more accurately than a using a thermistor. ... The LM35 has an output voltage that is proportional to the Celsius temperature.
|
- What is the output of lm35?
LM35 is a temperature measuring device having an analog output voltage proportional to the temperature. It provides output voltage in Centigrade (Celsius). It does not require any external calibration circuitry. The sensitivity of LM35 is 10 mV/degree Celsius.
|
LM35 can measure from -55 degrees centigrade to 150-degree centigrade. The accuracy level is very high if operated at optimal temperature and humidity levels. The conversion of the output voltage to centigrade is also easy and straight forward. The input voltage to LM35 can be from +4 volts to 30 volts.
|
- Can lm35 measure body temperature?
LM35 is used for the sense body temperature. ... This device will allow one to measure their mean arterial pressure (MAP) in about one minute and the accurate body temperature will be displayed on the Android.
|
- How do I calibrate my lm35 temperature sensor?
Make sure the instrument is connected in PSTrace. Click the 'Calibrate' button in the Settings window. The LM35 gives a voltage of 10 mV per measured centigrade. Calibration can be done by setting two points to determine both offset and slope of the linear relation or by just adjusting the offset.
|
- How do I connect my lm35?
Connect LM35 to Arduino uno as shown in circuit diagram. The +5v for LM35 can be taken from the +5v out pin of arduino uno. Also the ground pin of LM35 can be connected to GND pin of arduino uno. Connect Vout (the analog out of LM35) to any of the analog input pin of arduino uno.
|