SLUSES9 July   2022 TPS563300

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  Fixed Frequency Peak Current Mode
      2. 7.3.2  Pulse Frequency Modulation
      3. 7.3.3  Voltage Reference
      4. 7.3.4  Output Voltage Setting
      5. 7.3.5  Enable and Adjusting Undervoltage Lockout
      6. 7.3.6  Minimum On Time, Minimum Off Time, and Frequency Foldback
      7. 7.3.7  Frequency Spread Spectrum
      8. 7.3.8  Overvoltage Protection
      9. 7.3.9  Overcurrent and Undervoltage Protection
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes Overview
      2. 7.4.2 Heavy Load Operation
      3. 7.4.3 Light-Load Operation
      4. 7.4.4 Dropout Operation
      5. 7.4.5 Minimum On-Time Operation
      6. 7.4.6 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Output Voltage Resistors Selection
        3. 8.2.2.3 Bootstrap Capacitor Selection
        4. 8.2.2.4 Undervoltage Lockout Set Point
        5. 8.2.2.5 Output Inductor Selection
        6. 8.2.2.6 Output Capacitor Selection
        7. 8.2.2.7 Input Capacitor Selection
        8. 8.2.2.8 Feedforward Capacitor CFF Selection
        9. 8.2.2.9 Maximum Ambient Temperature
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.4.3 Light-Load Operation

For PFM version, when the load current is lower than half of the peak-to-peak inductor current in CCM, the device operates in discontinuous conduction mode (DCM), also known as diode emulation mode (DEM). In DCM operation, the LS switch is turned off when the inductor current drops to ILS_ZC (150 mA typical) to improve efficiency. Both switching losses and conduction losses are reduced in DCM when compared to forced CCM operation at light load.

At even lighter current load, pulse frequency modulation (PFM) mode is activated to maintain high efficiency operation. When either the minimum on time, tON_MIN, or the minimum peak inductor current, IPEAK_MIN (typically 750 mA) is reached, the switching frequency decreases to maintain regulation. In PFM mode, switching frequency is decreased by the control loop to maintain output voltage regulation when load current reduces. Switching loss is further reduced in PFM operation due to less frequent switching actions. The output current for mode change depends on the input voltage, inductor value, and the programmed switching frequency. For applications where the switching frequency must be known for a given condition, the transition between PFM and CCM must be carefully tested before the design is finalized.