SLVSHR3 July   2024

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  VCC Power Supply
      2. 6.3.2  EXTVCC Power Supply
      3. 6.3.3  Input Undervoltage Lockout
      4. 6.3.4  Enable and Programmable UVLO
      5. 6.3.5  Soft Start
      6. 6.3.6  Shutdown
      7. 6.3.7  Switching Frequency
      8. 6.3.8  Switching Frequency Dithering
      9. 6.3.9  Inductor Current Limit
      10. 6.3.10 Internal Charge Path
      11. 6.3.11 Output Voltage Setting
      12. 6.3.12 Output Current Monitoring and Cable Voltage Droop Compensation
      13. 6.3.13 Output Current Limit
      14. 6.3.14 Overvoltage Protection
      15. 6.3.15 Output Short Circuit Protection
      16. 6.3.16 Power Good
      17. 6.3.17 Constant Current Output Indication
      18. 6.3.18 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 PWM Mode
      2. 6.4.2 Power Save Mode
  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 Switching Frequency
        2. 7.2.2.2 Output Voltage Setting
        3. 7.2.2.3 Inductor Selection
        4. 7.2.2.4 Input Capacitor
        5. 7.2.2.5 Output Capacitor
        6. 7.2.2.6 Output Current Limit
        7. 7.2.2.7 Loop Stability
      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 Third-Party Products Disclaimer
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.8 Switching Frequency Dithering

The TPS551892-Q1 provides an optional switching frequency dithering that is enabled by connecting a capacitor from the DITH/SYNC pin to ground. Figure 6-4 illustrates the dithering circuit. By charging and discharging the capacitor, a triangular waveform centered at 1V is generated at the DITH/SYNC pin. The triangular waveform modulates the oscillator frequency by ±7% of the nominal frequency set by the resistance at the FSW pin. The capacitance at the DITH/SYNC pin sets the modulation frequency. A small capacitance modulates the oscillator frequency at a fast rate than a large capacitance. For the dithering circuit to effectively reduce peak EMI, the modulation rate normally is below 1kHz. Equation 4 calculates the capacitance required to set the modulation frequency, FMOD.

Equation 4. TPS551892-Q1

where

  • RFSW is the switching frequency setting resistance (Ω) at the FSW pin
  • FMOD is the modulation frequency (Hz) of the dithering

Connecting the DITH/SYNC pin below 0.4V or above 1.2V disables switching frequency dithering. The dithering function also is disabled when an external synchronous clock is used.

TPS551892-Q1 Switching Frequency DitheringFigure 6-4 Switching Frequency Dithering