Introduction
The LM317 Adjustable Voltage Regulator IC is one of the most popular linear regulators used in electronic circuits for providing stable and adjustable output voltage. Unlike fixed regulators such as the 7805 or 7812, the LM317 can deliver an output voltage ranging from 1.25V to 37V, making it a versatile choice for power supply design. It can supply up to 1.5A of output current with proper heat dissipation, making it suitable for both low-power and medium-power applications.
Designed for reliability, ease of use, and flexibility, the LM317 is widely used in DIY electronics, industrial circuits, and embedded systems. Its output voltage is adjusted using two external resistors, providing a simple way to generate custom voltage levels. The IC also features internal current limiting, thermal shutdown, and safe-area compensation, which makes it highly reliable under various load and temperature conditions.
LM317 Adjustable Voltage Regulator IC
The LM317 voltage regulator IC is available in different packages, including TO-220, TO-3, and SMD types, to suit different circuit requirements. Thanks to its wide input voltage range and built-in protection features, it has become a standard regulator in battery chargers, LED drivers, power supply units, and voltage reference circuits.
LM317 Pinout
LM317 Pinout / Block Diagram
LM317 Key Features
- Adjustable output voltage from 1.25V to 37V
- Output current up to 1.5A
- Built-in current limiting and thermal overload protection
- Safe-area compensation for enhanced reliability
- Requires only two external resistors to set the output voltage
- Available in multiple packages: TO-220, TO-3, and SMD
- Line and load regulation better than standard fixed regulators
- Suitable for single and dual power supply designs
LM317 Specifications/Characteristics
- Input Voltage Range: 3V to 40V
- Output Voltage Range: 1.25V to 37V (adjustable)
- Output Current: Up to 1.5A
- Load Regulation: 0.1% (typical)
- Line Regulation: 0.01% (typical)
- Power Dissipation: 20W (with proper heat sink)
- Dropout Voltage: ~2V to 3V
- Operating Junction Temperature: 0°C to +125°C
- Package Types: TO-220, TO-3, SOT-223, D2PAK
Note: DATASHEET DOWNLOAD button is provided end of this article.
Pin Configuration of LM317 Voltage Regulator IC
| Pin# | Pin Name | Pin Description |
|---|---|---|
| 1 | Adjust | Used to adjust the output voltage using resistor divider network |
| 2 | Output | Provides regulated output voltage |
| 3 | Input | Unregulated DC input voltage (3V to 40V) |
More Circuit Layouts
Key Applications of LM317 Voltage Regulator IC
- Adjustable regulated power supplies
- Battery chargers
- LED drivers with current control
- Constant current sources
- Bench power supplies for electronics testing
- Motor control circuits
- Voltage reference circuits
- Embedded system power regulation
LM317 Equivalent ICs / Alternatives
- LM337 – Negative adjustable voltage regulator
- LM338 – Higher current version (up to 5A)
- LM350 – Medium current version (up to 3A)
- AMS1117 (for low current applications)
- L200 (adjustable regulator with current limiting)
(The pinout for certain ICs can vary from that of the LM317).
Datasheet of LM317 Voltage Regulator IC
Click the following Button below to download the datasheet of LM317 :
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