SNVS775L March   2000  – January 2018 LM317L-N

PRODUCTION DATA.  

  1. Features
  2. Applications
    1.     Schematic Diagram
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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. 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. 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. 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

Package Options

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

External Capacitors

An input bypass capacitor is recommended in case the regulator is more than 6 inches away from the usual large filter capacitor. A 0.1-μF disc or 1-μF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive to the absence of input bypassing when adjustment or output capacitors are used, but the above values will eliminate the possibility of problems.

The adjustment terminal can be bypassed to ground on the LM317L-N to improve ripple rejection and noise. This bypass capacitor prevents ripple and noise from being amplified as the output voltage is increased. With a 10-μF bypass capacitor 80-dB ripple rejection is obtainable at any output level. Increases over 10-μF do not appreciably improve the ripple rejection at frequencies above 120 Hz. If the bypass capacitor is used, it is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.

In general, the best type of capacitors to use is solid tantalum. Solid tantalum capacitors have low impedance even at high frequencies. Depending upon capacitor construction, it takes about 25 μF in aluminum electrolytic to equal 1-μF solid tantalum at high frequencies. Ceramic capacitors are also good at high frequencies; but some types have a large decrease in capacitance at frequencies around 0.5 MHz. For this reason, a 0.01-μF disc may seem to work better than a 0.1-μF disc as a bypass.

Although the LM317L-N is stable with no output capacitors, like any feedback circuit, certain values of external capacitance can cause excessive ringing. This occurs with values between 500 pF and 5000 pF. A 1-μF solid tantalum (or 25-μF aluminum electrolytic) on the output swamps this effect and insures stability.