SLUS888G JANUARY   2009  – September 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Fault Recovery
      2. 7.3.2 Maximum On-Time and Brown Out
      3. 7.3.3 External Shutdown Using the MOT Pin
      4. 7.3.4 Overvoltage Detection
      5. 7.3.5 Solving for High Frequency Ringing
        1. 7.3.5.1 Identification of High Frequency Ringing
        2. 7.3.5.2 Avoid HF Ringing
        3. 7.3.5.3 Ferrite Chip or Bead Solution
        4. 7.3.5.4 DRV Capacitor Solution
        5. 7.3.5.5 Gate Turn-Off Resistor Solution
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Transformer Selection
      2. 8.1.2 Cascode Bias and Start-Up
      3. 8.1.3 Feedback Function Feedback Function text.
      4. 8.1.4 Modulation Modes
      5. 8.1.5 Primary Current Sense
      6. 8.1.6 Zero Crossing Detection
      7. 8.1.7 Green Mode Operation
      8. 8.1.8 Maximum Converter Power Limitation
      9. 8.1.9 Minimum Converter Power Limitation
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Bulk Capacitance and Minimum Bulk Voltage
        2. 8.2.2.2 Transformer Selection
        3. 8.2.2.3 Feedback Function Feedback Function text.
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

9 Power Supply Recommendations

The UCC28610 VDD can be charged through high-voltage MOSFET directly from the high-voltage bus at startup. Due to the nature of high loss, this charging path is intended for startup operation only. During normal operation, the VDD voltage should be high enough to avoid this high-loss charging path.

In order to achieve the lowest possible no-load power, select the number of turns in the bias winding so that VDD is higher than 16V-VTH of the high voltage MOSFET. A bias winding voltage between 17 V and 20 V usually achieves minimum loss. The bias winding often tracks the primary leakage inductance turn-off voltage spike. Place a 20-V Zener diode between VDD and GND in applications where the heavy loads cause excessive VDD voltage.