The Engineering Projects

Introduction to LM317

Hello everyone! I hope you all will be absolutely fine and having fun. Today, I am going to explore my knowledge about Introduction to LM317. It is basically a positive voltage regulator having three terminals. It can a supply a current more than 1.5A and voltage in a range of 1.25V to around 37V. You should also have a look at this LM 317 Calculator. For the adjustment of output voltage only two external resistors are required. It has improved standards of line regulation as well as load regulation. Full overload protection e.g. current limiting, area protection can be achieved using LM317. If its adjusting terminal is disconnected, even then all of the protection circuits will work properly. We can also use LM317 as precision current regulator by inserting a constant resistor between its adjustment terminal and output terminal. LM317 has a wide range of applications e.g. constant regulators, battery chargers, microprocessors supplies, automatic LED lightning, Ethernet switch, femto base station, hydraulic valve, IP phone, motor controllers, power bank solutions, power quality monitoring, Embedded Systems etc.

Introduction to LM317

LM317 is a positive voltage regulator with three different terminals Adjust, Vout and Vin respectively. It can supply the output voltage in a range of 1.25-37V and a current more than 1.5A. It has advanced line regulation and load regulation standards as compared to the general regulators. It has a lot of applications in rela life e.g. motor controllers, power bank solutions, hydraulic valve, ethernet switch, battery chargers etc. Download LM317 Datasheet

1. LM317 Pinout

• LM 317 has three (3) pins in total Adjust, Vout and Vin respectively.
• Each of the pins has its own functions, all the pins along with their name and numbers are shown in table given below.

2. LM317 Pins Configuration

• LM 317 pins configurations along with the properly labeled diagram is shown in the figure below.

• The animated LM317, its symbolic representation and the image of the real LM317 all are shown in the above figure.

3. LM317 Working Principle

LM 317 works on a very simple principle. It is a variable voltage regulator i.e. supports different output voltage levels for a constant applied input voltage supply. A variable resistor is connected at its Adjustment (Adj) terminal in order to control the level of the output voltage according to the requirements of the circuit. In other words we can say that LM 317 can step down the voltage from 12V to several different lower levels.

4. LM317 Packages and Dimensions

• A lot of LM 317 packages and their dimensions are provided along with their System International (SI) units in the table shown below.

• Description of packages along with their dimensions is given in the table above.

5. LM317 Specifications

• The different specifications associated with LM 317 are provided in the table given below.

6. LM317 Applications

LM 317 has a very wide range of application, a few of which are given below.

• Washing machine.
• Waveform generator.
• Refrigerator.
• Programmable Logic Controller (PLC).
• Power quality meter.
• Motor controllers.
• Finger prints.
• Ethernet switch.
• Private branch exchange.
• Constant current regulators.
• Microprocessors supplies.
• Automotive LED lightning.
• Battery chargers, the proper design of the circuit is shown in the figure below.

7. LM317 Proteus Simulation

• I have made a simulation in Proteus ISIS for voltage regulator.
• The screenshot of the simulation is shown in the figure below.

• The running form of the above simulation is shown in the figure below.

• Input, output and variable resistor are encircled in the above figure.
• Since its a variable voltage regulator so by changing the value of variable resistor you can obtained different voltage levels at the output.
• In the above figure, for the resistance of 61% the output voltage is 7.88V.
• Now, I am going to check the voltage level for the different value of variable resistor, which is 54% in this case.
• The output of the simulation is shown in the figure below.

• For the different value of variable resistor the output voltage has also changed from 7.88V to 8.27V.
• That was the detailed description of the voltage regulator simulation.
• You should also have a look at LM 317 Voltage Regulator in Proteus.
• You should also read Introduction to 7805, which is also a voltage regulator and is used to convert 12V into 5V.
• You can download this LM317 Proteus Simulation by clicking below button:

Download LM317 Datasheet

• In the below video, I have shown you how to simulate LM317 in Proteus:

So, that is all from the tutorial Introduction to LM317.  I hope you all have enjoyed this exciting tutorial. If you face any sort of problem you can ask me in comments anytime you want without even feeling any kind of hesitation. I will try my level best to solve your issues in some better way if possible. Our team is here to entertain you 24/7. I will explore further IC's and transistors in my upcoming tutorials and will surely share all of them with all of you as well. So, till then, take care :)

LM317 Voltage Regulator in Proteus

Hello friends, hope you all are fine and having fun. In today's post we are gonna have a look at LM317 Voltage Regulator in Proteus. In the previous post, we have seen how to design a 5V Power Supply in Proteus ISIS, which I have designed using IC regulator 7805. Today I am going to share How to design LM317 Voltage Regulator Circuit in Proteus. This DC power supply is a variable one means you can set its output voltage to any level you want. In order to change its output value we have used a variable resistor and by changing its value you can change the output value. It is a basic level project and very simple but used as a base to design large industrial projects. In this project, we are going to control the speed of a DC Motor and the corresponding voltages, appearing across it. The reason for designing this variable DC power supply is that, when you are working on some engineering project then each electronic module has its own power level i.e. xbee module works on 3.3V while Arduino board works on 5V. So, there's a need to design such power supply which can provide variable voltages and we can set them according to our demand. So, for all Microcontrollers like Arduino or PIC Microcontroller or 8051 Microcontroller, I designed 5V Power supply using 7805 but for 3.3V modules like XBee, NRF24L01 etc I design this variable DC power supply using LM317. I hope now you got the importance of this LM317 Voltage Regulator.

To design this, we will be using LM317k. Basically, it is a Voltage Regulator IC. It has 3 pins. Pin # 2 is for input voltages, marked as VI. Pin # 3 is for output voltages, marked as VO, and pin # 1 is used for Regulating Voltages and it is marked as ADJ. Further, if you notice the circuit diagram, which is given in the figure, then you will see that pin # 1 is connected to a Potentiometer. Potentiometer is a Variable Resistor device and it is also known as Voltage Divider. The feature of this electronic device is that, we can adjust the voltage through it according to our own choice. It operates on 12 Volts and it gives us ease that, we can adjust its voltages from 0 to MAXIMUM (which is 12 volts in most cases). Further if we notice the circuit, then we will see that a LED is connected in parallel with a simple DC motor and a voltmeter is also connected in parallel with Motor to monitor the voltages appearing across it. Above information was a little demo about the individual components of the circuit, now let’s be practical and move towards Hardware and see how actually Electronic components respond. You should also have a look at Introduction to LM317, if you wanna read all the basics about it. So let's get started with LM317 Voltage Regulator in Proteus:

LM317 Voltage Regulator in Proteus ISIS

• You can download this complete LM317 Voltage Regulator simulation by clicking the below button but I recommend you to design it on your own so that you learn most from it.

Download Proteus Simulation

• First of all, place all the components in Proteus workspace, as shown in image:

• A 12-Volt DC supply is provided to input pin (# 2) of LM317 and potentiometer is connected to Adjustable pin of LM317, which is, pin # 1.

• At output pin we have connected DC Motor and a Voltmeter is also connected in parallel with Motor.

• The complete circuit, ready for simulation is shown below in image:

Stage # 1

• Set the potentiometer at 0% and run the simulation, you will notice that Motor will rotate very slowly in clock-wise direction and 1.25 volts will appear on the voltmeter across it. If all the connections are OK, and when you will run the simulation, LM317 Voltage Regulator simulation will look like as shown in the image below:

Note:

• If you don't want to use the variable resistance, then you should use this LM317 Calculator to get value of your second resistance.

Stage # 2

• Now, set the potentiometer value to 11% and you will see that, Motor will start to rotate with a faster rate and on voltmeter scale, we will see 6.40 volts. In this setting, the interesting thing is, LED will start to Flash and it will turn ON & OFF automatically. This phenomenon can be seen in images below:

• Stage # 2 is our transient stage. When the potentiometers setting is below 11%, voltage appears across the motor and it also rotates but LED doesn’t glow. On the other hand, when potentiometers setting is above 11%, then LED glows continuously while motor also rotates as before, and voltmeter also gives some particular values of voltages appearing across the motor.

Stage # 3

• Now at final stage, set potentiometer to 100% and you will observe that motor is rotating with full speed and voltmeter reading will be 10.6 volts while LED is glowing continuously. This stage of the simulation can be seen in the image below:

Now, we can conclude that, LM317 is the monitoring device of this circuit. We can set the value of potentiometer according to our own choice and by this, the speed of motor can be controlled and also the corresponding voltages, appearing across it.

Here's the video in which I have given the detailed introduction of LM317 and have also run its simulation:

Alright friends, that's all for today and I hope now you can easily design this LM317 Voltage Regulator. In the next post, I have discussed DC Motor Drive circuit in Proteus ISIS . Till than take care and be safe !!! :)