SLUSF78A June   2023  – November 2024 UCC28731-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     Pin Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Detailed Pin Description
        1. 6.3.1.1 VDD (Device Bias Voltage Supply)
        2. 6.3.1.2 GND (Ground)
        3. 6.3.1.3 HV (High Voltage Startup)
        4. 6.3.1.4 DRV (Gate Drive)
        5. 6.3.1.5 CBC (Cable Compensation)
        6. 6.3.1.6 VS (Voltage Sense)
        7. 6.3.1.7 CS (Current Sense)
      2. 6.3.2 Primary-Side Regulation (PSR)
      3. 6.3.3 Primary-Side Constant Voltage Regulation
      4. 6.3.4 Primary-Side Constant Current Regulation
      5. 6.3.5 Valley-Switching and Valley-Skipping
      6. 6.3.6 Startup Operation
      7. 6.3.7 Fault Protection
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Input Bulk Capacitance and Minimum Bulk Voltage
        2. 7.2.2.2 Transformer Turns Ratio, Inductance, Primary-Peak Current
        3. 7.2.2.3 Transformer Parameter Verification
        4. 7.2.2.4 Output Capacitance
        5. 7.2.2.5 VDD Capacitance, CVDD
        6. 7.2.2.6 VS Resistor Divider, Line Compensation, and Cable Compensation
      3. 7.2.3 Application Curves
    3. 7.3 Do's and Don'ts
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
        1. 8.1.1.1  Capacitance Terms in Farads
        2. 8.1.1.2  Duty-Cycle Terms
        3. 8.1.1.3  Frequency Terms in Hertz
        4. 8.1.1.4  Current Terms in Amperes
        5. 8.1.1.5  Current and Voltage Scaling Terms
        6. 8.1.1.6  Transformer Terms
        7. 8.1.1.7  Power Terms in Watts
        8. 8.1.1.8  Resistance Terms in Ω
        9. 8.1.1.9  Timing Terms in Seconds
        10. 8.1.1.10 DC Voltage Terms in Volts
        11. 8.1.1.11 AC Voltage Terms in Volts
        12. 8.1.1.12 Efficiency Terms
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.1 Application Information

The UCC28731-Q1 device is a PSR controller optimized for isolated-flyback AC or DC-to-DC supply applications in the 5W to 50W range, providing constant-voltage (CV) mode control and constant current (CC) mode control for precise output regulation. Higher-power, multiple-output applications and other variations may also be supported. It is capable of switching at a very low frequency to facilitate achieving stand-by input power consumption of less than 5mW.