SNVS775L March   2000  – January 2018 LM317L-N

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Schematic Diagram
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Rating
    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
      3. 7.4.3 DSBGA Light Sensitivity
  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  Digitally-Selected Outputs
      3. 8.2.3  High Gain Amplifier
      4. 8.2.4  Adjustable Current Limiter
      5. 8.2.5  Precision Current Limiter
      6. 8.2.6  Slow Turnon 15-V Regulator
      7. 8.2.7  Adjustable Regulator With Improved Ripple Rejection
      8. 8.2.8  High Stability 10-V Regulator
      9. 8.2.9  Adjustable Regulator With Current Limiter
      10. 8.2.10 0-V to 30-V Regulator
      11. 8.2.11 Regulator With 15-mA Short-Circuit Current
      12. 8.2.12 Power Follower
      13. 8.2.13 Adjusting Multiple On-Card Regulators With Single Control
      14. 8.2.14 100-mA Current Regulator
      15. 8.2.15 1.2-V to 12-V Regulator With Minimum Program Current
      16. 8.2.16 50-mA Constant Current Battery Charger for Nickel-Cadmium Batteries
      17. 8.2.17 5-V Logic Regulator With Electronic Shutdown
      18. 8.2.18 Current-Limited 6-V Charger
      19. 8.2.19 Short Circuit-Protected 80-V Supply
      20. 8.2.20 Basic High-Voltage Regulator
      21. 8.2.21 Precision High-Voltage Regulator
      22. 8.2.22 Tracking Regulator
      23. 8.2.23 Regulator With Trimmable Output Voltage
      24. 8.2.24 Precision Reference With Short-Circuit Proof Output
      25. 8.2.25 Fully-Protected (Bulletproof) Lamp Driver
      26. 8.2.26 Lamp Flasher
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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7.1 Overview

In operation, the LM317L-N develops a nominal 1.25-V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program resistor R1 and, because the voltage is constant, a constant current I1 then flows through the output set resistor R2, giving an output voltage of:

Equation 1. LM317L-N 906447.png

Because the 100-μA current from the adjustment terminal represents an error term, the LM317L-N was designed to minimize IADJ and make it very constant with line and load changes. To do this, all quiescent operating current is returned to the output establishing a minimum load current requirement. If there is insufficient load on the output, the output will rise.

LM317L-N 906407.pngFigure 13. Typical Application Circuit for Adjustable Regulator