SLUSFU4 September   2024 TPS51388

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  PWM Operation and D-CAP3™ Control Mode
      2. 6.3.2  VCC Switchover Function
      3. 6.3.3  Soft Start
      4. 6.3.4  Large Duty Operation
      5. 6.3.5  Power Good
      6. 6.3.6  Overcurrent Protection and Undervoltage Protection
      7. 6.3.7  Overvoltage Protection
      8. 6.3.8  UVLO Protection
      9. 6.3.9  Output Voltage Discharge
      10. 6.3.10 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Light Load Operation
      2. 6.4.2 Advanced Eco-mode Control
      3. 6.4.3 Out-of-Audio™ Mode
      4. 6.4.4 Mode Selection
      5. 6.4.5 Standby Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Custom Design With WEBENCH® Tools
        2. 7.2.2.2 External Component Selection
          1. 7.2.2.2.1 VOUT and FB Pin Configuration
          2. 7.2.2.2.2 MODE Selection
          3. 7.2.2.2.3 Inductor Selection
          4. 7.2.2.2.4 Output Capacitor Selection
          5. 7.2.2.2.5 Input Capacitor Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Tape and Reel Information

6.3.2 VCC Switchover Function

VCC switchover function is designed to bypass internal 5V LDO with the power from BYP and enhance light load efficiency. The VCC switchover is a seamless behavior of regulator and does not need any additional configuration.

The VCC pin switchover function is asserted when conditions are present:

  • PGOOD is not pulled low
  • VOUT voltage is higher than 4.8V and BYP pin is short to VOUT; Or external BYP voltage is higher than 4.8V.

In this switchover condition, one thing occurs: the VCC output is connected to BYP by internal switchover MOSFET. This BYP external voltage must come after VIN voltage on and quit before VIN off.