SLVS696D October   2008  – April 2020

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic
      2.      Efficiency versus Output Current
  4. 4 Revision History
  5. 5 Output Voltage Options
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Device Enable
      2. 8.3.2 Undervoltage Lockout
      3. 8.3.3 Overtemperature Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Soft Start and Short Circuit Protection
      2. 8.4.2 Buck-Boost Operation
      3. 8.4.3 Power-Save Mode and Synchronization
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Programming the Output Voltage
        2. 9.2.2.2 Inductor Selection
        3. 9.2.2.3 Capacitor Selection
          1. 9.2.2.3.1 Input Capacitor
          2. 9.2.2.3.2 Bypass Capacitor
          3. 9.2.2.3.3 Output Capacitor
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.4.1 Soft Start and Short Circuit Protection

After being enabled, the device starts operating. The average current limit ramps up from zero to the nominal current limit value. Thus, the output voltage overshoot at start-up, as well as the inrush current, is kept at a minimum. The device ramps up the output voltage in a controlled manner, even if a very large capacitor is connected at the output.

At an overload or short circuit condition at the output, the average current limit protects the device itself and the application. Higher change rates of output current or input voltage can trigger an additional built-in short circuit protection mode, which reduces the current limit to less than 50% of the nominal current limit. In this mode, the switching frequency can be reduced as well.