SLUSDW0B May   2020  – May 2020 UCC28065

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Principles of Operation
      2. 8.3.2  Natural Interleaving
      3. 8.3.3  On-Time Control, Maximum Frequency Limiting, Restart Timer and Input Voltage Feed-Forward compensation
      4. 8.3.4  Zero-Current Detection and Valley Switching
      5. 8.3.5  Phase Management and Light-Load Operation
      6. 8.3.6  Burst Mode Operation
      7. 8.3.7  External Disable
      8. 8.3.8  Improved Error Amplifier
      9. 8.3.9  Soft Start
      10. 8.3.10 Brownout Protection
      11. 8.3.11 Line Dropout Detection
      12. 8.3.12 VREF
      13. 8.3.13 VCC
      14. 8.3.14 System Level Protections
        1. 8.3.14.1 Failsafe OVP - Output Over-voltage Protection
        2. 8.3.14.2 Overcurrent Protection
        3. 8.3.14.3 Open-Loop Protection
        4. 8.3.14.4 VCC Undervoltage Lock-Out (UVLO) Protection
        5. 8.3.14.5 Phase-Fail Protection
        6. 8.3.14.6 CS - Open, TSET - Open and Short Protection
        7. 8.3.14.7 Thermal Shutdown Protection
        8. 8.3.14.8 Fault Logic Diagram
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  Inductor Selection
        2. 9.2.2.2  ZCD Resistor Selection RZA, RZB
        3. 9.2.2.3  HVSEN
        4. 9.2.2.4  Output Capacitor Selection
        5. 9.2.2.5  Selecting RS For Peak Current Limiting
        6. 9.2.2.6  Power Semiconductor Selection (Q1, Q2, D1, D2)
        7. 9.2.2.7  Brownout Protection
        8. 9.2.2.8  Converter Timing
        9. 9.2.2.9  Programming VOUT
        10. 9.2.2.10 Voltage Loop Compensation
      3. 9.2.3 Application Curves
        1. 9.2.3.1 Input Ripple Current Cancellation with Natural Interleaving
        2. 9.2.3.2 Brownout Protection
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Package Option Addendum
      1. 13.1.1 Packaging Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.3.14.1 Failsafe OVP - Output Over-voltage Protection

Failsafe OVP prevents any single failure from allowing the output to boost above safe levels. Redundant paths for output voltage sensing provide additional protection against output over-voltage. Over-voltage protection is implemented through two independent paths: VSENSE and HVSEN.

VSENSE pin voltage is compared with two levels of over-voltage. If the lower one, VLOW_OV,is exceeded the COMP pin is discharged by an internal 2-kΩ resistance until the output voltage falls below VLOW_OV reduced of 2% to provide hysteresis (ΔVLOW_OV_HYST). If also the higher over-voltage threshold is exceeded in addition to activate the 2-kΩ pull down switching is soon disabled. In order to re-enable the switching the sensed voltage has to fall below VLOW_OV reduced of 2%. Additional over-voltage protection can be implemented on HVSEN pin through a separate resistor divider to monitor output voltage. An over-voltage is detected if HVSEN pin voltage exceeds VHV_OV_FLT an as consequence device stops switching and the 2-kΩ pull down is activated. The pull down 2-kΩ pull down is removed only if HVSEN pin goes below VHV_OV_CLR threshold and the COMP pin is fully discharged to 20 mV. Both conditions needs to be true before the soft-start can begin.

The converter shuts down if either input senses a severe over-voltage condition. The output voltage can still remain below a safe limit if either sense path fails. The device is re-enabled when both sense inputs fall back into their normal ranges. At that time, the gate drive outputs will resume switching under PWM control. A low-level over-voltage on VSENSE does not trigger soft-start, an higher-level over voltage on VSENSE additionally shuts off the gate-drive outputs until the OV clears, but still does not trigger a soft-start. However, an over-voltage detected on HVSEN does trigger a full soft-start and the COMP pin is fully discharged to 20 mV before the soft-start can begin.