SLUSF98 November   2024 TPSM84338

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  Fixed Frequency Peak Current Mode
      2. 6.3.2  Mode Selection
      3. 6.3.3  Voltage Reference
      4. 6.3.4  Output Voltage Setting
      5. 6.3.5  Switching Frequency Selection, Synchronization
      6. 6.3.6  Phase Shift
      7. 6.3.7  Enable and Adjusting Undervoltage Lockout
      8. 6.3.8  External Soft Start and Prebiased Soft Start
      9. 6.3.9  Power Good
      10. 6.3.10 Minimum On Time, Minimum Off Time, and Frequency Foldback
      11. 6.3.11 Frequency Spread Spectrum
      12. 6.3.12 Overvoltage Protection
      13. 6.3.13 Overcurrent and Undervoltage Protection
      14. 6.3.14 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Modes Overview
      2. 6.4.2 Heavy Load Operation
      3. 6.4.3 Pulse Frequency Modulation
      4. 6.4.4 Forced Continuous Conduction Modulation
      5. 6.4.5 Dropout Operation
      6. 6.4.6 Minimum On-Time Operation
      7. 6.4.7 Shutdown Mode
  8. 7 Application and Implementation
    1. 7.1 Typical Application
      1. 7.1.1 Design Requirements
      2. 7.1.2 Detailed Design Procedure
        1. 7.1.2.1 Custom Design With WEBENCH® Tools
        2. 7.1.2.2 Output Voltage Resistors Selection
        3. 7.1.2.3 Choosing Switching Frequency
        4. 7.1.2.4 Soft-Start Capacitor Selection
        5. 7.1.2.5 Output Capacitor Selection
        6. 7.1.2.6 Input Capacitor Selection
        7. 7.1.2.7 Feedforward Capacitor CFF Selection
        8. 7.1.2.8 Maximum Ambient Temperature
      3. 7.1.3 Application Curves
    2. 7.2 Best Design Practices
    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. 8.1.2 Development Support
        1. 8.1.2.1 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

Package Options

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

6.3.6 Phase Shift

When the TPSM84338 works in FCCM mode with SYNC to external clock, the phase shift function can be activated by adding a capacitor connect to MODE pin, as is shown in Figure 6-4. When the phase shift function is disabled, let the capacitor float. The phase shift function is designed to reduce the input ripple and improve EMI performance for multi-rails, where step-down converters share the same input. Figure 6-5 shows how phase shift reduces input ripple with three buck converters sharing the same input. The capacitor value can be calculated using Equation 3, where CMODE is the MODE capacitor, θ is the degree of phase shift. Table 6-4 shows the typical capacitor value for the phase shift configuration.

Equation 3. C M O D E = θ - 28 ° 1.3585
TPSM84338 Phase Shift Operation Schematic Figure 6-4 Phase Shift Operation Schematic
TPSM84338 Phase Shift Operation Application TPSM84338 Phase Shift Operation Application Figure 6-5 Phase Shift Operation Application
Table 6-4 Phase Shift Configuration
Recommended Mode Capacitor, pF Phase Shift, Degree
47pF 90°
68pF 120°
120pF 180°
180pF 270°