SNVS039J June   2000  – April 2015 LM1086

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  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 Ripple Rejection
      2. 7.3.2 Load Regulation
      3. 7.3.3 Overload Recovery
    4. 7.4 Device Functional Modes
      1. 7.4.1 Output Voltage
      2. 7.4.2 Stability Consideration
      3. 7.4.3 Protection Diodes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1  1.2-V to 15-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  Adjustable at 5 V
      3. 8.2.3  5-V Regulator with Shutdown
      4. 8.2.4  Battery Charger
      5. 8.2.5  Adjustable Fixed Regulator
      6. 8.2.6  Regulator With Reference
      7. 8.2.7  High Current Lamp Driver Protection
      8. 8.2.8  Battery Backup Regulated Supply
      9. 8.2.9  Ripple Rejection Enhancement
      10. 8.2.10 Automatic Light Control
      11. 8.2.11 Remote Sensing
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Development Support
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.1 Ripple Rejection

Ripple rejection is a function of the open loop gain within the feed-back loop (refer to Figure 13 and Figure 16). The LM1086 exhibits 75dB of ripple rejection (typ.). When adjusted for voltages higher than VREF, the ripple rejection decreases as function of adjustment gain: (1+R1/R2) or VO/VREF. Therefore a 5-V adjustment decreases ripple rejection by a factor of four (−12dB); Output ripple increases as adjustment voltage increases.

However, the adjustable version allows this degradation of ripple rejection to be compensated. The adjust terminal can be bypassed to ground with a capacitor (CADJ). The impedance of the CADJ should be equal to or less than R1 at the desired ripple frequency. This bypass capacitor prevents ripple from being amplified as the output voltage is increased.

Equation 1. 1/(2π*fRIPPLE*CADJ) ≤ R1