TIDUFG2 December   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Sensor Selection
    3. 2.3 Highlighted Products
      1. 2.3.1 TLV387
      2. 2.3.2 TLV9054
      3. 2.3.3 MSPM0G5187-LP
      4. 2.3.4 LOG300
      5. 2.3.5 UCC28881
      6. 2.3.6 TPS709
  9. 3System Design Theory
    1. 3.1 Current Sensor
    2. 3.2 Hybrid Integrator
    3. 3.3 Band-Pass Filter
      1. 3.3.1 Log Amplifier
      2. 3.3.2 Current Low-Pass Filter
      3. 3.3.3 Non-isolated Voltage Sensing
      4. 3.3.4 Auto Labeling Circuit
        1. 3.3.4.1 Line Voltage Sensing
        2. 3.3.4.2 Arc Gap Voltage Sensing
        3. 3.3.4.3 Differential to Single-Ended Conversion
      5. 3.3.5 Power Supply
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software
    3. 4.3 Test Setup
      1. 4.3.1 Arc Testing Setup
    4. 4.4 Test Results
  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
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

3.3.5 Power Supply

TIDA-010971 Power Supply Schematic Figure 3-15 Power Supply Schematic

This auxiliary power supply takes a 110V to 250VAC input and provides a stable 3.3V rail. UCC28881 offline switcher steps down the voltage. With no load present, the 5V rail exceeds 5V, limited by D3 at 8.2V. MOV R29 and diode D7 add overvoltage protection. This supply tests the analog portion of the board, but remains optional. The 3V3 rail does not power the auto labeling portion of the board because the LaunchPad connection handles data transfer. If 110V to 250VAC input lacks power the LaunchPad 5V rail routes to provide an input to LDO U5.