TIDUFC8 July   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Introduction
      2. 2.2.2 Basic Operation Principles and ZVS Requirements
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC27288
      2. 2.3.2 UCC23513
      3. 2.3.3 TMS320F2800137
      4. 2.3.4 TLV9062
      5. 2.3.5 INA181
      6. 2.3.6 TPSM861252
      7. 2.3.7 AMC0311R
  9. 3System Design Theory
    1. 3.1 Design Theory
      1. 3.1.1 Resonant Tank Design
      2. 3.1.2 Full-Range ZVS Realization
      3. 3.1.3 Total Control Algorithm
      4. 3.1.4 Resonant Tank RMS Current Analysis
    2. 3.2 Hardware Design Theory
      1. 3.2.1 Resonant Capacitors
      2. 3.2.2 Power Stage
      3. 3.2.3 Voltage Sensing
      4. 3.2.4 Current Sensing
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
      1. 4.2.1 Simulation
    3. 4.3 Test 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
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Layout Prints
    2. 5.2 Tools
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

3.2.4 Current Sensing

Regardless of whether running the design in the forward or reverse mode, this design needs to sense the input current to do constant current loop. The primary-side current must be sensed. Due to the need for the system to operate in both directions, there are two directions in the direction of the input current.

Figure 3-8 shows the primary current sensing circuit. INA181 is used to sense bidirectional current. Select a 1mΩ sampling resistor placed at the low side, the current is less than 20A, so that means the limit of the common-mode voltage is –0.2V to 26V.

TIDA-010966 Primary Current Sensing CircuitFigure 3-8 Primary Current Sensing Circuit