TIDUF39 March   2025

 

  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
    3. 2.3 Highlighted Products
      1. 2.3.1 DAC70502: Dual-Channel, 1-LSB INL, 14-Bit, SPI Voltage-Output Digital-to-Analog Converter (DAC)
      2. 2.3.2 INA818: 35μV Offset, 8nV/√Hz Noise, Low-Power, Precision Instrumentation Amplifier
      3. 2.3.3 OPA192: High-Voltage, Rail-to-Rail Input/Output, 5µV, 0.2µV/°C, Precision Operational Amplifier
      4. 2.3.4 LM5146: 100V Synchronous Buck DC/DC Controller With Wide Duty Cycle Range
  9. 3System Design Theory
    1. 3.1 Constant Current Control Design
    2. 3.2 Constant Current and Voltage Simulation
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
    3. 4.3 Test Setup
      1. 4.3.1 Constant Current Test Setup
      2. 4.3.2 Constant Voltage Test Setup
    4. 4.4 Test Results
      1. 4.4.1 Current Control Accuracy
      2. 4.4.2 Voltage Control Accuracy
      3. 4.4.3 CC, CV Transformation
      4. 4.4.4 Constant Current Transient Response
      5. 4.4.5 Constant Voltage Transient Response
      6. 4.4.6 Voltage Ripple at Short Circuit
      7. 4.4.7 Tracking DC-DC output
  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

2.2 Design Considerations

This reference design features low-noise, two-quadrant linear power supply with flexibility of output voltage adjustment. To improve efficiency, a tracking pre-regulator is implemented using the LM5146 buck converter for voltage tracking configuration to minimize the headroom of the discrete two-quadrant linear power stage.

Precise current sense is implemented using INA818, and LM358 is used to measure the output voltage. The current and voltage sense signals are fed into the analog feedback loop which controls the gate voltage of the power MOSFET. A DAC70502 14-bit , 2-channel DAC, is used to set the output current and voltage. The DAC is programmed using a USB2ANY adapter.