TIDUA71 January   2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TAS6584-Q1
      2. 2.3.2 LM5123-Q1
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Results
      1. 3.2.1 Class-H Tracking Waveform Example
      2. 3.2.2 Thermal Performance
  9. 4Design and Documentation Support
    1. 4.1 Design Files
    2. 4.2 Support Resources
    3. 4.3 Trademarks
  10. 5About the Author

3.2.2 Thermal Performance

Figure 3-3 through Figure 3-6 are thermal images that demonstrate the improvement in efficiency of the system when running the system with Class-H. This was tested with a simple 1-kHz sine wave that would vary between full power for 100 ms and one-eighth of full power for 900 ms repeatedly. The system was allowed to reach a stable temperature before capturing with a thermal camera. When examining the system thermally, there are key areas that show significant improvement:

  1. The low-side MOSFET of the boost
  2. The boost inductor
  3. Output filter inductors of the Class-D amplifier

Class-H operation allows these key areas to operate with lower average currents at lower voltages, significantly reducing thermal losses.

GUID-20211215-SS0I-JRWZ-PTMG-7VGWKXBBCWXN-low.jpgFigure 3-3 Thermal Image of Boost Powertrain With Class-H Disabled
GUID-20211215-SS0I-RQFZ-LVJW-LXZ3KPQHN8X5-low.jpgFigure 3-5 Thermal Image of Amplifier Output Inductors With Class-H Disabled
GUID-20211215-SS0I-34MP-THJ4-6DVTW8HSBMXQ-low.jpgFigure 3-4 Thermal Image of Boost Powertrain With Class-H Enabled
GUID-20211215-SS0I-RVQX-PGTL-R53M5GXRCNKN-low.jpgFigure 3-6 Thermal Image of Amplifier Output Inductors With Class-H Enabled