The LM317 is an adjustable linear voltage regulator, which can supply 1.5A of current and has an output voltage range of 1.2V to 37V. This regulator is very simple to use, requiring only two external resistors to set the output voltage. This IC is used in a variety of applications, especially in electronic circuits where a stable voltage is required. It is a three-terminal adjustable regulator that can be used to provide a wide range of output voltages from a single input voltage source.

Function: 1.5A Adjustable Output, Positive Voltage Regulator

Package: TO-220, D2Pak-3 Type

Manufacturer: ON Semiconductor

Pinouts:

Description

The IC Low Dropout (LDO) Linear Voltage Regulator is an adjustable 3-terminal positive LDO voltage regulator capable of supplying in excess of 1.5 A over an output voltage range of 1.2 V to 37 V. This voltage regulator is exceptionally easy to use and requires only two external resistors to set the output voltage. Further, it employs internal current limiting, thermal shutdown and safe area compensation, making it essentially blow-out proof.

LDO regulators operate particularly efficiently at low input-to-output voltage differentials, making them ideal for battery-powered devices or low-power applications. For example, they help extend battery life in electronic devices such as mobile phones, laptops, or portable music players.

The working principle of an LDO regulator is relatively simple. When an input voltage is supplied to the regulator, the internal circuitry passes only as much current as is necessary to maintain the set output voltage. The heat generated during this process is managed by an internal thermal shutdown function, preventing the device from overheating. In addition, a current limiting function prevents the circuit from being overloaded, and a safety zone compensation ensures that the voltage regulator operates within a safe power range.

The Device serves a wide variety of applications including local, on card regulation. This device can also be used to make a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317 can be used as a precision current regulator.

For example, if we want to supply a stable voltage of 5V to a certain electronic device, we can achieve this by using LM317. For this, we need to connect two resistors to LM317. These resistors are used to determine the output voltage of the regulator, and through this, we can obtain the desired voltage.

The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. The device features a typical line regulation of 0.01% and typical load regulation of 0.1%. It includes current limiting, thermal overload protection, and safe operating area protection. Overload protection remains functional even if the ADJUST terminal is disconnected.

The LM317 also has a variety of protection features to ensure that the circuit operates safely. For example, the current limiting function prevents excessive current from flowing through the circuit, and thermal overload protection prevents the device from overheating. Safe operating area protection ensures that the regulator operates within the safe power range. In addition, the overload protection function is maintained even when the ADJUST terminal is disconnected, further improving the reliability of the device.

Features

1. Output Voltage Range Adjustable From 1.25 V to 37 V

2. Output Current Greater Than 1.5 A

3. Internal Short-Circuit Current Limiting

4. Thermal Overload Protection

5. Output Safe-Area Compensation

Block Diagram:

1. Adjustable output: Users can adjust the voltage through external resistors to obtain the required voltage.

2. Wide voltage range: It provides a wide adjustment range from 1.2V to 37V.

3. High current capacity: It can supply up to 1.5A of current.

Applications:

• ATCA Solutions

• DLP: 3D Biometrics, Hyperspectral Imaging, Optical Networking, and Spectroscopy

• DVR and DVS

• Desktop PC

• Digital Signage and Still Camera

• ECG Electrocardiogram

• EV HEV Charger: Level 1, 2, and 3

• Electronic Shelf Label

• Energy Harvesting
• Ethernet Switch

• Femto Base Station

• Fingerprint and Iris Biometrics

Application Circuit

Components with similar functions to LM317

1. The LM1117 is a low dropout voltage regulator IC that has a voltage range of 1.25V to 13.8V and a maximum output current of 1A. It is similar to the LM317 in that it provides a variable output voltage, but it has a lower dropout voltage, which means it can regulate the voltage even when the input voltage is close to the output voltage. The LM1117 is often used in battery-powered applications where a stable output voltage is required even when the battery voltage is low.

2. Compared to the LM7805, the LM317 and LM1117 offer the advantage of providing an adjustable output voltage, while the LM7805 is fixed. Compared to the LM1117, the LM317 offers a wider voltage range and can handle higher output currents, but it has a higher dropout voltage. The choice of voltage regulator IC depends on the specific requirements of the application.

LM317 Datasheet

Official Homepage: https://www.onsemi.com/PowerSolutions/product.do?id=LM317

Reference Site: LM317 – Wikipedia, the free encyclopedia

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