SNVSAC2A March   2015  – June 2020 LM317A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Typical Application
  3. 3 Description
    1.     Revision History
  4. 4 Device Comparison Table
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Load Regulation
    4. 7.4 Device Functional Modes
      1. 7.4.1 External Capacitors
      2. 7.4.2 Protection Diodes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1  1.25-V to 25-V Adjustable Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2  5-V Logic Regulator With Electronic Shutdown
      3. 8.2.3  Slow Turnon 15-V Regulator
      4. 8.2.4  Adjustable Regulator With Improved Ripple Rejection
      5. 8.2.5  High-Stability 10-V Regulator
      6. 8.2.6  High-Current Adjustable Regulator
      7. 8.2.7  Emitter-Follower Current Amplifier
      8. 8.2.8  1-A Current Regulator
      9. 8.2.9  Common-Emitter Amplifier
      10. 8.2.10 Low-Cost 3-A Switching Regulator
      11. 8.2.11 Current-Limited Voltage Regulator
      12. 8.2.12 Adjusting Multiple On-Card Regulators With Single Control
      13. 8.2.13 AC Voltage Regulator
      14. 8.2.14 12-V Battery Charger
      15. 8.2.15 Adjustable 4-A Regulator
      16. 8.2.16 Current-Limited 6-V Charger
      17. 8.2.17 Digitally-Selected Outputs
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Thermal Considerations
        1. 10.1.1.1 Heatsink Requirements
        2. 10.1.1.2 Heatsinking Surface Mount Packages
          1. 10.1.1.2.1 Heatsinking the SOT-223 (DCY) Package
          2. 10.1.1.2.2 Heatsinking the TO-252 (NDP) Package
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.3 Slow Turnon 15-V Regulator

An application of LM317A includes a PNP transistor with a capacitor to implement slow turnon functionality (see Figure 21). As VIN rises, the PNP sinks current from the ADJ rail. The output voltage at start up is the addition of the 1.25-V reference plus the drop across the base to emitter. While this is happening, the capacitor begins to charge and eventually opens the PNP. At this point, the device functions normally, regulating the output at 15 V. A diode is placed between C1 and VOUT to provide a path for the capacitor to discharge. Such controlled turnon is useful for limiting the in-rush current.

LM317A 906309-1.gifFigure 21. Slow Turnon 15-V Regulator