SLVSGA9A March   2022  – August 2022 TPS55289

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 I2C Timing Characteristics
    7. 6.7 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  VCC Power Supply
      2. 7.3.2  EXTVCC Power Supply
      3. 7.3.3  Operation Mode Setting
      4. 7.3.4  Input Undervoltage Lockout
      5. 7.3.5  Enable and Programmable UVLO
      6. 7.3.6  Soft Start
      7. 7.3.7  Shutdown and Load Discharge
      8. 7.3.8  Switching Frequency
      9. 7.3.9  Switching Frequency Dithering
      10. 7.3.10 Inductor Current Limit
      11. 7.3.11 Internal Charge Path
      12. 7.3.12 Output Voltage Setting
      13. 7.3.13 Output Current Monitoring and Cable Voltage Droop Compensation
      14. 7.3.14 Output Current Limit
      15. 7.3.15 Overvoltage Protection
      16. 7.3.16 Output Short Circuit Protection
      17. 7.3.17 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Mode
      2. 7.4.2 Power Save Mode
    5. 7.5 Programming
      1. 7.5.1 Data Validity
      2. 7.5.2 START and STOP Conditions
      3. 7.5.3 Byte Format
      4. 7.5.4 Acknowledge (ACK) and Not Acknowledge (NACK)
      5. 7.5.5 Target Address and Data Direction Bit
      6. 7.5.6 Single Read and Write
      7. 7.5.7 Multiread and Multiwrite
    6. 7.6 Register Maps
      1. 7.6.1 REF Register (Address = 0h, 1h)
      2. 7.6.2 IOUT_LIMIT Register (Address = 2h) [reset = 11100100h]
      3. 7.6.3 VOUT_SR Register (Address = 3h) [reset = 00000001h]
      4. 7.6.4 VOUT_FS Register (Address = 4h) [reset = 00000011h]
      5. 7.6.5 CDC Register (Address = 5h) [reset = 11100000h]
      6. 7.6.6 MODE Register (Address = 6h) [reset = 00100000h]
      7. 7.6.7 STATUS Register (Address = 7h) [reset = 00000011h]
  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 Switching Frequency
        2. 8.2.2.2 Output Voltage Setting
        3. 8.2.2.3 Inductor Selection
        4. 8.2.2.4 Input Capacitor
        5. 8.2.2.5 Output Capacitor
        6. 8.2.2.6 Output Current Limit
        7. 8.2.2.7 Loop Stability
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.9 Switching Frequency Dithering

The TPS55289 provides an optional switching frequency dithering that is enabled by connecting a capacitor from the DITH/SYNC pin to ground. Figure 7-4 illustrates the dithering circuit. By charging and discharging the capacitor, a triangular waveform centered at 1 V 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 faster rate than a large capacitance. For the dithering circuit to effectively reduce peak EMI, the modulation rate normally is below 1 kHz. Equation 4 calculates the capacitance required to set the modulation frequency, FMOD.

Equation 4. GUID-82AE4153-0DA2-4600-994B-4955EB314B67-low.gif

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 0.4 V or above 1.2 V disables switching frequency dithering. The dithering function also is disabled when an external synchronous clock is used.

GUID-AB3EE0F2-A7FB-4E89-BBB9-82A16959BEA4-low.gifFigure 7-4 Switching Frequency Dithering