LM317 Pinout, Equivalent, Uses, Features and Other Details
LM317 is a very famous adjustable voltage regulator IC available in many different packages. Today we are going to discuss about LM317 pinout, equivalent, uses, features and other details about this IC.
LM317 IC Features / Technical Specifications
- Capable of providing upto 1.5A current at the output.
- Voltage adjustable from 1.2V to 37V
- Requires low external components
- Requires only two external resistors for output adjustment.
- Capable of short circuit protection
- Over heat shutdown function
- Low price
- Reliable to use in commercial applications
- Maximum input voltage is 40V DC
- Low standby current
LM317 Explained / Description
Previously we have discussed some fixed voltage regulator ICs like LM7805, LM7806, LM7809, LM7812 and LM7815. All these ICs are designed to provide a fixed output voltage. But if there is requirement of adjustable output voltage then LM317 might be a good choice. LM317 is a widely used adjustable positive voltage regulator IC available in many different packages. The IC is widely used in commercial equipment and also by electronic students and learners. It is also one of a famous IC among electronic hobbyists and tinkerers. The main reason for its wide usage is because it contains entire adjustable regulated power supply circuitry in a single chip due to which one can easily make a low cost and reliable adjustable power supply of 1.2V to 37V DC output voltage with upto 1.5A output current capability and very low external components. Moreover the IC also contains many other features like short circuit protection, safe area and over heat protection which also makes it full proof and long term performer. Two external resistors can be used to adjust the output voltage of the IC. For getting a stable output the input voltage must be 2 to 3 volt higher than the output.
Additionally the LM317 IC is not limited to use for power supply circuits but it can also be used in many other applications.
The application circuit shown in the above “LM317 IC pinout” image can be used to make LM317 power supply. The maximum input voltage can be applied to the circuit is 40V DC with 2 to 3 ampere. The output is adjustable from 1.2V to 37V DC with max output current of 1.5A. The output voltage can be adjusted with the help of 5K variable resistor. The 40V input is not mandatory you can provide any voltage between 3V to 40V DC, depends on your output voltage requirements. For example if you want to build a 1.2V to 12V adjustable power supply then provide 3V higher than your maximum output voltage. In the above requirement of 1.2V to 12V supply the input voltage must not less than 15V.
Voltage step down circuits
Lab power supplies
Solar Power Supplies
Microcontroller Related Applications
DC to DC converters
Replacement and Equivalent / Other Part Numbers
LM117, LM217, LM1086-ADJ, LT1086-ADJ, LT1117-ADJ, B29150, LM338, LM1084-ADJ. Some ICs may have different pin configuration from LM317, therefore check pin configuration before using in a circuit.
How to Safely Long Run in a Circuit
To get stable and long term performance from LM317 do not provide input voltage more than 40V DC, do not drive load of more than 1.5A, always use a proper heatsink with the IC and always operate in temperature above -55 centigrade and below +150 centigrade. The storage temperature is from -65 centigrade to +150 centigrade.
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