SLUSAO7C September   2011  – July 2024 UCC28063

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Principles of Operation
      2. 7.3.2  Natural Interleaving
      3. 7.3.3  On-Time Control, Maximum Frequency Limiting, and Restart Timer
      4. 7.3.4  Distortion Reduction
      5. 7.3.5  Zero-Current Detection and Valley Switching
      6. 7.3.6  Phase Management and Light-Load Operation
      7. 7.3.7  External Disable
      8. 7.3.8  Improved Error Amplifier
      9. 7.3.9  Soft Start
      10. 7.3.10 Brownout Protection
      11. 7.3.11 Dropout Detection
      12. 7.3.12 VREF
      13. 7.3.13 VCC
      14. 7.3.14 Control of Downstream Converter
      15. 7.3.15 System Level Protections
        1. 7.3.15.1 Failsafe OVP - Output Overvoltage Protection
        2. 7.3.15.2 Overcurrent Protection
        3. 7.3.15.3 Open-Loop Protection
        4. 7.3.15.4 VCC Undervoltage Lock-Out (UVLO) Protection
        5. 7.3.15.5 Phase-Fail Protection
        6. 7.3.15.6 CS-Open, TSET-Open and -Short Protection
        7. 7.3.15.7 Thermal Shutdown Protection
        8. 7.3.15.8 AC-Line Brownout and Dropout Protections
        9. 7.3.15.9 Fault Logic Diagram
    4. 7.4 Device Functional Modes
  9. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Inductor Selection
        2. 8.2.2.2  ZCD Resistor Selection (RZA, RZB)
        3. 8.2.2.3  HVSEN
        4. 8.2.2.4  Output Capacitor Selection
        5. 8.2.2.5  Selecting (RS) For Peak Current Limiting
        6. 8.2.2.6  Power Semiconductor Selection (Q1, Q2, D1, D2)
        7. 8.2.2.7  Brownout Protection
        8. 8.2.2.8  Converter Timing
        9. 8.2.2.9  Programming VOUT
        10. 8.2.2.10 Voltage Loop Compensation
      3. 8.2.3 Application Curves
        1. 8.2.3.1 Input Ripple Current Cancellation with Natural Interleaving
        2. 8.2.3.2 Brownout Protection
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Related Parts
      2. 11.1.2 Device Nomenclature
        1. 11.1.2.1 Detailed Pin Description
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Mechanical, Packaging, and Orderable Information

8.2.2.3 HVSEN

The HVSEN pin programs the PWMCNTL output of the UCC28063. The PWMCNTL open-drain output can be used to disable a downstream converter while the PFC output capacitor is charging. PWMCNTL starts high impedance and pulls to ground when HVSEN increases above 2.5 V. Setting the point where PWMCNTL becomes active requires a voltage divider from the boost voltage to the HVSEN pin to ground. Equation 25 to Equation 30 show how to set the PWMCNTL pin to activate when the output voltage is within 90% of its nominal value.

Equation 25. UCC28063

Resistor RE sets up the high side of the voltage divider and programs the hysteresis of the PWMCNTL signal. For this example, RE was selected to provide 99 V of hysteresis, as shown in Equation 26. Three resistors in series were used to meet voltage requirements.

Equation 26. UCC28063

Resistor RF is used to program the PWMCNTL active threshold, as shown in Equation 27.

Equation 27. UCC28063

Select a standard resistor value for RF.

Equation 28. UCC28063

This PWMCNTL output will remain active until a minimum output voltage (VOUT_MIN) is reached, as shown in Equation 29.

Equation 29. UCC28063

According to these resistor values, the FailSafe OVP threshold will be set according to Equation 30

Equation 30. UCC28063