SLVSHI9A March   2025  – September 2025 TPS7H5020-SEP , TPS7H5020-SP

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Quality Conformance Inspection
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Input Voltage (VIN) and VLDO
      2. 7.3.2  Driver Input Voltage (PVIN)
      3. 7.3.3  Start-Up
      4. 7.3.4  Enable and Undervoltage Lockout (UVLO)
      5. 7.3.5  Voltage Reference
      6. 7.3.6  Error Amplifier
      7. 7.3.7  Output Voltage Programming
      8. 7.3.8  Soft Start (SS)
      9. 7.3.9  Switching Frequency and External Synchronization
        1. 7.3.9.1 Internal Oscillator Mode
        2. 7.3.9.2 External Synchronization Mode
          1. 7.3.9.2.1 External Synchronization with TPS7H5021
      10. 7.3.10 Duty Cycle Limit
      11. 7.3.11 Minimum On-Time and Off-Time
      12. 7.3.12 Pulse Skipping
      13. 7.3.13 Leading Edge Blank Time
      14. 7.3.14 Current Sense and PWM Generation (CS_ILIM)
      15. 7.3.15 Gate Driver Output
      16. 7.3.16 Unpowered Voltage Clamp
      17. 7.3.17 Sourcing Driver Return (OUTH_REF)
      18. 7.3.18 Slope Compensation (RSC)
      19. 7.3.19 Frequency Compensation
      20. 7.3.20 Thermal Shutdown
    4. 7.4 Device Functional Modes
  9. 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 Programming Resistor Selection
        3. 8.2.2.3  Driver PVIN Configuration
        4. 8.2.2.4  Soft-Start Capacitor Selection
        5. 8.2.2.5  Transformer Design
        6. 8.2.2.6  Primary Power Switch Selection
        7. 8.2.2.7  Output Diode Selection
        8. 8.2.2.8  RCD Clamp
        9. 8.2.2.9  Output Capacitance Selection
        10. 8.2.2.10 Current Sense Resistor
        11. 8.2.2.11 Frequency Compensation Component Selection
      3. 8.2.3 Application Curves
      4. 8.2.4 Boost Converter
      5. 8.2.5 Feedback Isolation Using ISOS510
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.6 Primary Power Switch Selection

In the flyback topology, the maximum voltage that can be applied at the drain of the FET is calculated according to Equation 55.

Equation 55. VDS=VIN_MAX+VL+NPS×VOUT+VD
Equation 56. VDS=36V+12V+2×5V+0.7V=59.4V

At a minimum, a 60V rated FET is needed for the application. Practically, a FET with a higher voltage rating needs to be selected to allow for transient spikes and ringing. Furthermore, the current rating of the FET needs to be higher than the primary currents that were calculated in Transformer Design. The selected GaN device has a voltage rating of 200V, with a 22A current rating.