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

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • VAB|13
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6.4.2 Advanced Eco-mode Control

The advanced Eco-mode control schemes to maintain high light load efficiency. As the output current decreases from heavy load conditions, the inductor current is also reduced and eventually comes to a point where the rippled valley touches zero level, which is the boundary between continuous conduction and discontinuous conduction modes. The rectifying MOSFET is turned off when the zero inductor current is detected. As the load current further decreases, the converter runs into discontinuous conduction mode. The on-time is kept almost the same as in continuous conduction mode so that discharging the output capacitor with smaller load current to the level of the reference voltage takes longer. This action makes the switching frequency lower, proportional to the load current, and keeps the light load efficiency high. Use Equation 2 to calculate the light load current where the transition to Eco-mode operation happens (IOUT(LL)).

Equation 2. I O U T L L = 1 2 × L O U T × F S W × V I N - V O U T × V O U T V I N

After identifying the application requirements, design the output inductance (LOUT) so that the inductor peak-to-peak ripple current is approximately between 20% and 40% of IOUT(ma×) (peak current in the application). Sizing the inductor properly so that the valley current does not hit the negative low-side current limit is important.