LM317T: Adjustable voltage regulator, 1.2-37V, 1.5A, TO-220

The LM317T from STMicroelectronics is an adjustable voltage regulator, capable of delivering output voltages ranging from 1.2V to 37V with a maximum output current of 1.5A. It is designed to provide a highly flexible voltage regulation option, accommodating a wide range of applications. The device features excellent line and load regulation characteristics, ensuring stable output voltage despite variations in input voltage and load. Moreover, it includes a comprehensive suite of protections, including current limiting, thermal shutdown, and safe operating area (SOA) control, enhancing its reliability in demanding environments.

The LM317T is available in a TO-220 package, making it suitable for a variety of mounting styles and thermal management strategies. Its nominal output voltage is easily adjustable through a simple resistive divider, simplifying the design process and reducing the need for multiple fixed regulators. This adjustability, combined with its robust protection features, makes the LM317T a versatile choice for designers seeking a reliable and flexible voltage regulation solution.

Key Specifications and Features

  • Output Voltage Range: 1.2V to 37V
  • Output Current: Up to 1.5A
  • Line Regulation: 0.01% to 0.04%/V
  • Load Regulation: 0.1% to 0.5%
  • Adjustment Pin Current: 50 to 100µA
  • Minimum Load Current: 3.5mA to 10mA
  • Maximum Load Current: Up to 1.5A
  • Output Voltage Temperature Stability: 1%
  • Supply Voltage Rejection: 65 to 80dB

LM317T Datasheet

LM317T datasheet (PDF)

LM317T Substitutes
Equivalent alternate parts that may serve as a substitute for LM317T, most popular parts first


  • Power Supplies: Adjustable output for custom voltage requirements
  • Battery Chargers: Controlled charging voltage
  • Laboratory Equipment: Precision voltage regulation for experiments
  • LED Drivers: Adjustable voltage for driving LEDs
  • Consumer Electronics: Voltage regulation in various devices


Voltage Regulators

General information

Adjustable voltage regulators like the LM317T are integral components in electronic systems, offering the flexibility to provide a variable output voltage from a fixed input voltage. They are essential for applications requiring precise voltage control across different loads and operating conditions. When selecting an adjustable voltage regulator, engineers consider factors such as output voltage range, current capability, thermal performance, and protection features.

The LM317T exemplifies a reliable adjustable voltage regulator, suitable for a broad spectrum of applications from power supplies to consumer electronics. Its wide output voltage range and current capability enable it to cater to diverse design requirements. The device's line and load regulation ensure stable operation across various conditions, while its protection features safeguard against overcurrent and overheating scenarios.

Designers often choose adjustable voltage regulators for their versatility and ease of use. With the ability to set the output voltage through external resistors, these components can replace multiple fixed regulators, simplifying inventory and design complexity. However, attention must be paid to thermal management and the selection of external components to ensure optimal performance and reliability.

In conclusion, the LM317T and similar adjustable voltage regulators offer a practical solution for custom voltage regulation needs. Their adaptability, combined with robust protection mechanisms, make them invaluable in designing reliable and efficient electronic systems.

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