SLVS044Z September   1997  – April 2025 LM317

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information (Legacy Chip)
    5. 6.5 Thermal Information (New Chip)
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 NPN Darlington Output Drive
      2. 7.3.2 Overload Block
      3. 7.3.3 Programmable Feedback
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Operation With Low Input Voltage
      3. 7.4.3 Operation at Light Loads
      4. 7.4.4 Operation In Self Protection
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1  0V to 30V Regulator Circuit
      2. 8.3.2  Adjustable Regulator Circuit With Improved Ripple Rejection
      3. 8.3.3  Precision Current-Limiter Circuit
      4. 8.3.4  Tracking Preregulator Circuit
      5. 8.3.5  1.25V to 20V Regulator Circuit With Minimum Program Current
      6. 8.3.6  Battery-Charger Circuit
      7. 8.3.7  50mA, Constant-Current, Battery-Charger Circuit
      8. 8.3.8  Slow Turn-On 15V Regulator Circuit
      9. 8.3.9  AC Voltage-Regulator Circuit
      10. 8.3.10 Current-Limited 6V Charger Circuit
      11. 8.3.11 Adjustable 4A Regulator Circuit
      12. 8.3.12 High-Current Adjustable Regulator Circuit
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Thermal Considerations
          1. 8.5.1.1.1 Heat Sink Requirements
          2. 8.5.1.1.2 Heat Sinking Surface-Mount Packages
            1. 8.5.1.1.2.1 Heatsinking the SOT-223 (DCY) Package
            2. 8.5.1.1.2.2 Heat Sinking the TO-263 (KTT) Package
      2. 8.5.2 Layout Examples
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

3 Description

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

Typically, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors. In that case, an input bypass is needed. Add an optional output capacitor to improve transient response. Bypass the adjustment pin to achieve very high ripple rejection ratios that are difficult to achieve with standard 3-pin regulators.

Package Information
PART NUMBER PACKAGE(1) PACKAGE SIZE(2)
LM317 DCY (SOT-223, 4) 6.5mm × 7mm
KTT (TO-263, 3) 10.16mm × 15.24mm
KCS, KCT (TO-220, 3)(3) 10.16mm × 4.55mm
(1) For more information, see the Mechanical, Packaging, and Orderable Information.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.
(3) Legacy chip.

 

LM317 Battery-Charger Circuit Battery-Charger Circuit

The regulator is floating and detects only the input-to-output differential voltage. Thus, supplies of several hundred volts are regulated as long as the maximum input-to-output differential is not exceeded. That is, avoid short-circuiting the output.

By connecting a fixed resistor between the adjustment pin and output, the LM317 is also able to be used as a precision current regulator. Supplies with electronic shutdown are achieved by clamping the adjustment terminal to ground, which programs the output to 1.25V where most loads draw little current.