ZHCSOX6C September   2021  – December 2022 UCC14240-Q1

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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  Power Ratings
    6. 6.6  Insulation Specifications
    7. 6.7  Safety-Related Certifications
    8. 6.8  Electrical Characteristics
    9. 6.9  Safety Limiting Values
    10. 6.10 Insulation Characteristics
    11. 6.11 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 Power Stage Operation
        1. 7.3.1.1 VDD-VEE Voltage Regulation
        2. 7.3.1.2 COM-VEE Voltage Regulation
        3. 7.3.1.3 Power Handling Capability
      2. 7.3.2 Output Voltage Soft Start
      3. 7.3.3 ENA and PG
      4. 7.3.4 Protection Functions
        1. 7.3.4.1 Input Undervoltage Lockout
        2. 7.3.4.2 Input Overvoltage Lockout
        3. 7.3.4.3 Output Overvoltage Protection
        4. 7.3.4.4 Overpower Protection
          1. 7.3.4.4.1 Output Undervoltage Protection
        5. 7.3.4.5 Overtemperature Protection
    4. 7.4 Device Functional Modes
  8. 8 Application 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 Capacitor Selection
        2. 8.2.2.2 RLIM Resistor Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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7.3.4.1 Input Undervoltage Lockout

UCC14240-Q1 can take wide input voltage range, from 21 V to 27 V. When the input voltage becomes too low, the output either cannot be regulated due to the transformer turns ratio limitation, or the converter operates with too much current stress. Either way, the converter must shut down to protect the system.

The UCC14240-Q1 enters input undervoltage lockout when VVIN voltage becomes lower than the UVLO threshold VVIN_UVLOP_FALLING. In UVLO mode, the converter stops switching. After VIN pin voltage becomes lower than the VIN analog undervoltage lockout falling threshold VVIN_VULOP_FALLING , UCC14240-Q1 resets all the protections. After that, after the VVIN voltage becomes above the UVLO threshold VVIN_UVLOP_RISING, the converter is enabled. Depending on the ENA pin voltage, the converter can start switching, go through the soft-start process, or in the disable mode, waiting for ENA pin voltage becomes high.