TIDUF59 March   2024

 

  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
      1. 2.2.1 PFC Inductance Design
      2. 2.2.2 Configuration of CS pin in LMG3622
      3. 2.2.3 AHB Topology and the VCC Design
      4. 2.2.4 LMG2610 for AHB Topology
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC28056
      2. 2.3.2 LMG3622
      3. 2.3.3 LMG2610
  9. 3Hardware, Test Requirements, and Test Results
    1. 3.1 Hardware
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Switching Waveform
        1. 3.3.1.1 Switching Waveform on the PFC Stage
        2. 3.3.1.2 Switching Waveform on the AHB Stage
      2. 3.3.2 Efficiency Test Result
      3. 3.3.3 Thermal Test Result
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 Layout Prints {Optional Section}
    2. 4.2 Tools
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author

Switching Waveform on the PFC Stage

The PFC stage was measured at 140W full load condition. The waveform of VDS and ZCD/CS pin was captured close to UCC28056 to confirm the operation of the PFC controller and TI-GaN.

The channel setting of Figure 3-7 to Figure 3-12 is:

  • Ch1: VDS voltage of the U1 (LMG3622)
  • CH2 is the ZCD/CS voltage of U2 (UCC28056)
GUID-20231211-SS0I-HLJQ-Z6XZ-MR0W4QF2HMVQ-low.svg
The operation frequency is 83.8kHz. The system works in CrM.
Figure 3-7 Switching Waveform of PFC Stage at 90Vac Input and 140W Load
GUID-20231211-SS0I-QTTV-LQL7-W3S0SX2GK3J2-low.svg
The operation frequency is 117.9kHz. The system works in CrM.
Figure 3-8 Switching Waveform of PFC Stage at 115Vac Input and 140W Load
GUID-20231211-SS0I-G588-C5ZZ-KX68KZ77LL2W-low.svg
The operation frequency is 78.86kHz. The system works in DCM.
Figure 3-9 Switching Waveform of PFC Stage at 230Vac Input and 140W Load
GUID-20231211-SS0I-9SXF-XNBM-2NN8PXXZXWR3-low.svg
The operation frequency is 37.88kHz. The system works in DCM.
Figure 3-10 Switching Waveform of PFC Stage at 264Vac Input and 140W Load

When the output voltage of the PFC is lower, the duty cycle and the operation frequency are lower.

GUID-20231211-SS0I-DGTC-CQM5-QHWR9MJ9TGD3-low.svg
The PFC output voltage is set as 320V. The operation frequency is 76.69kHz. The system works in CrM.
Figure 3-11 Switching Waveform of PFC Stage at 90Vac Input and 140W Load
GUID-20231212-SS0I-HDGJ-2SMG-LZ5M9C2XVZNP-low.svg
The PFC output voltage is set as 320V. The operation frequency is 102.5kHz. The system works in CrM.
Figure 3-12 Switching Waveform of PFC Stage at 115Vac Input and 140W Load