TIDUEZ3A April   2021  – June 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 LMG342xR030
      2. 2.3.2 TMS320F28002x
      3. 2.3.3 OPA607
      4. 2.3.4 UCC21222
  8. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Test Procedures
      2. 3.3.2 Performance Data: Efficiency, iTHD, and Power Factor
      3. 3.3.3 Functional Waveforms
        1. Current Sensing and Protection
        2. Power Stage Startup and Input Waveforms
        3. AC Drop Test
        4. Surge Test
        5. EMI Test
      4. 3.3.4 Thermal Test
      5. 3.3.5 GaN FET Switching Waveform
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  10. 5About the Author
  11. 6Revision History

System Overview

This system uses the TI C2000 controlCARD TMDSCNCD280049C (TMDSCNCD280025C compatible) as the controller and the TI GaN EVM board LMG3422EVM-043 as the fast switching leg.

This design moved the C2000 reference ground to the middle point of the MOSFET leg so it can use the OPA607 non-isolated, high-speed amplifier to sense the inductor current. With this benefit, the isolated drive UCC21222 must be changed for the low-speed MOSFET leg, and the LM358B amplifier is used for DC voltage sense. The MCU ground change does not affect GaN drive, as it is generally expected to have isolators to stop the switching noise transferring from the GaN FET to the controller side. On the GaN EVM board, the LMG3422R030 is isolated by the ISO7741F and powered by the SN6505 drive isolated DC/DC.

Instead of a bulky relay, this design uses a MOSFET driven by the UCC23511 for inrush protection, which saves on PCB space.

This design has a flyback board with the UCC28740 to generate two isolated 12 V outputs; one is for the control circuits and the other 12 V is for the low-side MOSFET drive. These two 12 V outputs are designed with 500-V isolation ability with each other, which could withstand the DC link voltage when the high-side MOSFET is turned on. The 12 V output for control circuits generates the 5-V power, with the TPS650430 buck controller for MCU card and GaN card, .

Additionally, this design includes an FSI communication port with the ISO7763 isolator, powered by the UCC21050. The FSI communication allows faster communications and firmware updates.