LM35 is used in industries and commercial buildings where high accuracy of temperature measuring is need. I will give you a detailed overview of this temperature sensor in today’s post where we will have a look its pinout, working, protocol etc. I will also share some links of projects where I have interfaced it with Arduino or other microcontrollers. If you have any question please ask in comments, i will resolve your quires and will guide you in comprehensive way.So, let’s get started with basic Introduction to LM35:
Introduction to LM35
- LM35 is a commonly used temperature sensor, It shows values in form of out put voltages instead of degree Celsius.
- LM35 shows high voltage values than thermocouples and may not need that the output voltage is amplified.
- The output voltage of LM35 is proportional to the Celsius temperature. The scale factor is .01 V/°C.
- One most important characteristic is that, it draws just 60 micro amps from its supply and acquires a low self-heating capacity.
- LM35 temperature sensor available in many different packages like T0-46 metal transistor-like package, TO-92 plastic transistor-like package, 8-lead surface mount SO-8 small outline package.
Lets have a look at LM35 PINOUT configuration:
- LM35 has three pinout which are:
- PIN 1: Vcc, it used as input at this pin we apply +5 V input voltage.
- PIN 2: At this pin we get output voltage.
- PIN 3: This pin is used for ground.
- Here’s the table for LM35 Pinout for better understanding:
|1.||Vcc||Power Pin ( Connected to +5V )|
|2||Vout||Output Pin (It should be connected with analog pin of Microcontroller)|
|3||Ground||Ground Pin ( Connected to 0V or GND )|
For better understanding lets, have a look at LM35 Pinout figure.
Lets have a look at working of LM35 Working.
Working of LM35
- LM35 is used to measure precise centigrade temperature.The output of this sensor changes describes the linearity. The output voltages of this sensor is linearly comparative to the Celsius temperature.
- The output voltage range of this sensor is from -55˚ to +150˚C. It also have low self heating power.
- Its operating voltages is 4 to 30 volts.
- In most circuit this sensor is used with operational amplifier. Amplifier is device which amplify applied voltage at certain level.
- Operational Amplifier has three terminal, first two are inverting and non inverting inputs third one is used for output.
- By using LM35 with operational amplifier we can get amplification of out put voltages of LM35.
- For better understanding lets have a look at circuit diagram.
- Its maximum and minimum input voltages are 35 V and -2 V respectively. It typically operate at 5 V.
- It can measure temperature from -55°C to 150°C.
- Its 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.
- Its Drain current is less than 60 uA.
- Its low cost temperature sensor.
- It is small and hence suitable for remote applications.
- It is available in TO-92, TO-220, TO-CAN and SO IC package.
- It is low self-heating, 0.08 C in still air n Non linearity only ±1⁄4C typical.
Parameters of LM35
Lets discuss some working parameters of LM35
|1.||Accuracy LM35, LM 35C||T A=+25˚C||±0.4||˚C|
|2||Accuracy, LM35D||T A=+25˚C||±0.6||˚C|
|3||Non linearity||T MIN≤TA≤T MAX||±0.3||˚C|
|4||Sensor Gain||T MIN≤TA≤T MAX||+10.0||mV/˚C|
|5||Load Regulation||T A=+25˚C||±0.4||mV/mA|
|6||Line Regulation||T A=+25˚C||±0.01||mV/V|
|7||Quiescent Current||V S=+5V, +25˚C||56||µA|
|8||Change of Quiescent Current||4V≤VS≤30V||0.2||µA|
|9||Temperature Coefficient of Quiescent Current||–||+0.39||µA/˚C|
|10||Long Term Stability T J=T MAX, for 1000 hours||±0.08||±0.08||˚C|
LM35 Interfaced with Aurdino
Now lets discuss LM35 interfacing with Arduino and design a simple project:
- The project which we are gonna discuss is Temperature Monitoring on Virtual Terminal of Arduino.
- Temperature Sensor we are gonna use is LM35.
- In this circuit Aurdino is main component because it controls all functions.
- In this circuit LM35 senses the temperature and converts into electoral (analogue) signal, then this signal applied to Microelectronic Unit through an analogue-to-digital converter (ADC).
- The analogue signal is converted into digital format by the ADC.
- The value of temperature sensed by sensor will be displayed on Serial Terminal or virtual Terminal if you are working on Proteus.
- You can download this complete Proteus simulation from Interfacing of LM35 with Arduino in Proteus.
- I have also shared Interfacing of LM35 with PIC Microcontroller, so if you are working on PIC Microcontroller then you should read that out.
- For better understanding lets see circuit diagram of this project:
Now, lets discus advantage and application of this project.
Lets have a look at applications of LM35:
Applications of LM35
These are some applications of LM35, let discuss them.
- Its used for measuring temperature of a particular environment.
- It provide thermal shutdown for a circuit or component used in specific project.
- It can be used for battery temperature measurement. It provides battery protection from overheating.
- It can be used in HVAC applications as temperature measurement device.
I hope you have enjoyed today’s tutorial on this simple temperature sensor LM35. Let me know if you need any help with its projects. Will meet you guys in next tutorial. Till then take care, have fun !!! 🙂