TIDUF57 November   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations [Required Topic]
    3. 2.3 Highlighted Products
      1. 2.3.1 LMG3624
  9. 3System Design Theory
    1. 3.1 Quasi-Resonant Operation
    2. 3.2 Transformer Design
    3. 3.3 GaN FET Switching Device
    4. 3.4 Current Sense Emulation Resistor
  10. 4Hardware, Testing Requirements, and Test Results
    1. 4.1 Required Hardware
      1. 4.1.1 Hardware
      2. 4.1.2 Testing Equipment
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 Efficiency Results
      2. 4.3.2 Thermal Results
      3. 4.3.3 Switching Waveforms
      4. 4.3.4 Switching Transients
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support [Required Topic]
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

1 System Description

This reference design focuses on optimizing power density and efficiency in a 65-W, USB PD 3.0 application. The key device that enables this operation is the primary switching device, LMG3624, 170-mΩ integrated GaN FET with current-sense emulation.

The design employs the quasi-resonant flyback topology with synchronous rectification to achieve a balance between performance and simplicity. The flyback transformer is kept to a minimum size by operating at high switching frequencies which enable a low magnetizing inductance requirement.

The design is able to deliver power to a USB PD 3.0 load with outputs of 20 V | 3.25 A, 15 V | 3 A, 9 V | 3 A, 5 V | 3 A.