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

7.4.4 Dropout Operation

The dropout performance of any buck converter is affected by the RDSON of the power MOSFETs, the DC resistance of the inductor, and the maximum duty cycle that the controller can achieve. As the input voltage level approaches the output voltage, the off time of the high-side MOSFET starts to approach the minimum value. Beyond this point, the switching frequency becomes erratic and the output voltage can fall out of regulation. To avoid this problem, the TPS563300 automatically reduces the switching frequency (on-time extension function) to increase the effective duty cycle and maintain in regulation until the switching frequency reach to the lowest limit of about 140 kHz, the period is equal to (tON_MAX + tOFF_MIN) (typically 7.14 μS). In this condition, the difference voltage between VIN and VOUT is defined as dropout voltage. The typical overall dropout characteristics can be found as Figure 7-6.

Figure 7-6 Overall Dropout Characteristic, VOUT = 5 V