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 of 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 real life e.g. motor controllers, power bank solutions, hydraulic valve, ethernet switch, battery chargers, etc.

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.

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 the table given below.

LM317 Applications

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

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

                                             LM317 Pinout