TIDUFF4 October   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
      1. 1.1.1 General TI High Voltage Evaluation User Safety Guidelines
        1. 1.1.1.1 Safety and Precautions
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 GaN Power Stage
      2. 2.2.2 Inductor
      3. 2.2.3 Controller
      4. 2.2.4 Cooling
        1. 2.2.4.1 Heat Sink Placement
        2. 2.2.4.2 Via Placement
        3. 2.2.4.3 Copper Block
    3. 2.3 Highlighted Products
      1. 2.3.1 LMG3100R017
      2. 2.3.2 UCD3138A
      3. 2.3.3 TPSM365R6V5
      4. 2.3.4 TMP61
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Software Requirements
    3. 3.3 Test Setup
    4. 3.4 Test Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 PCB Layout Recommendations
        1. 4.1.3.1 Power Loop Optimization
        2. 4.1.3.2 Return Current Through Output Power Ground
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author

2.2.2 Inductor

To deliver 2kW total power, each phase inductor must support 42A current. The inductor must also support higher saturation current, depending on the inductor current ripple and derating. Choose a low-Direct Current Resistance (DCR) inductor to reduce conduction losses that affect full load efficiency. The inductor size is another constraint. Four inductors must fit within a 36.8mm dimension to achieve a streamlined power flow across a 58.4mm dimension.

The smallest catalog, single inductors with these ratings occupy a large board area. To address this issue, the design uses the ERUC23-2R2K coupled inductor from TDK®. In a coupled inductor, both phases share the same part of the core. Negative magnetic coupling between the two phases occurs, resulting in ripple cancellation. This provides an added benefit of ripple cancellation at the output due to multiphasing.

For higher power and higher saturation rating for peak power delivery, choose a lower inductance value with a smaller DCR. An increase in the switching frequency can be required to reduce the ripple and switching losses in GaN.

The coupled inductor design offers several benefits:

  • Reduced current ripple: Magnetic coupling between phases enables significant ripple current cancellation, resulting in lower current ripple throughout the circuit.
  • Increased efficiency: Lower ripple currents reduce IRMS losses in GaN FETs, inductors, and PCB traces, helping improve converter efficiency overall.
  • Faster transient response: Lower inductance can be used for the same ripple, meaning a coupled inductor design allows for faster response to load changes, often reducing the need for bulky output capacitors.
  • Space and size savings: Using a single core for multiple windings means less board area and potentially smaller magnetics for the same current ratings.