SNVS817B June   2012  – June 2019 LMR12015 , LMR12020

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Descriptions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Recommended Operating Ratings
    3. 6.3 Electrical Characteristics
    4. 6.4 Typical Performance Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Boost Function
      2. 7.3.2  Low Input Voltage Considerations
      3. 7.3.3  High Output Voltage Considerations
      4. 7.3.4  Frequency Synchronization
      5. 7.3.5  Current Limit
      6. 7.3.6  Frequency Foldback
      7. 7.3.7  Soft Start
      8. 7.3.8  Output Overvoltage Protection
      9. 7.3.9  Undervoltage Lockout
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Operation Modes
      1. 7.4.1 Enable Pin / Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1  Custom Design With WEBENCH® Tools
        2. 8.2.1.2  Inductor Selection
          1. 8.2.1.2.1 Inductor Calculation Example
          2. 8.2.1.2.2 Inductor Material Selection
        3. 8.2.1.3  Input Capacitor
        4. 8.2.1.4  Output Capacitor
        5. 8.2.1.5  Catch Diode
        6. 8.2.1.6  Boost Diode (Optional)
        7. 8.2.1.7  Boost Capacitor
        8. 8.2.1.8  Output Voltage
        9. 8.2.1.9  Feedforward Capacitor (Optional)
        10. 8.2.1.10 Calculating Efficiency and Junction Temperature
          1. 8.2.1.10.1 Schottky Diode Conduction Losses
          2. 8.2.1.10.2 Inductor Conduction Losses
          3. 8.2.1.10.3 MOSFET Conduction Losses
          4. 8.2.1.10.4 MOSFET Switching Losses
          5. 8.2.1.10.5 IC Quiescent Losses
          6. 8.2.1.10.6 MOSFET Driver Losses
          7. 8.2.1.10.7 Total Power Losses
          8. 8.2.1.10.8 Efficiency Calculation Example
          9. 8.2.1.10.9 Calculating the LMR2015/20 Junction Temperature
      2. 8.2.2 Application Curves
      3. 8.2.3 LMR12015/20 Circuit Examples
  9. 9 Layout
    1. 9.1 Layout Considerations
      1. 9.1.1 Compact Layout
      2. 9.1.2 Ground Plane and Shape Routing
      3. 9.1.3 FB Loop
      4. 9.1.4 PCB Summary
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Related Links
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Community Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1.5 Catch Diode

The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching times and low forward voltage drop. The catch diode should be chosen so that its current rating is greater than:

Equation 26. ID1 = IOUT × (1-D)

The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin. To improve efficiency choose a Schottky diode with a low forward voltage drop.