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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7.3.1 Load Regulation

The LM317L-N is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 240 Ω) must be tied directly to the output of the regulator rather than near the load. This eliminates line drops from appearing effectively in series with the reference and degrading regulation. For example, a 15-V regulator with 0.05-Ω resistance between the regulator and load will have a load regulation due to line resistance of 0.05 Ω × IL. If the set resistor is connected near the load the effective line resistance will be 0.05 Ω (1 + R2/R1) or in this case, 11.5 times worse.

Figure 14 shows the effect of resistance between the regulator and 240-Ω set resistor.

With the TO-92 package, it is easy to minimize the resistance from the case to the set resistor, by using two separate leads to the output pin. The ground of R2 can be returned near the ground of the load to provide remote ground-sensing and improve load regulation.

LM317L-N 906408.pngFigure 14. Regulator With Line Resistance in Output Lead