ZHCSNM5C november   2020  – august 2023 UCC25800-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 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
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Power Management
      2. 8.3.2 Oscillator
      3. 8.3.3 External Synchronization
      4. 8.3.4 Dead-Time
        1. 8.3.4.1 Adaptive Dead-time
        2. 8.3.4.2 Maximum Programmable Dead-time
      5. 8.3.5 Protections
        1. 8.3.5.1 Overcurrent Protection
          1. 8.3.5.1.1 OCP Threshold Setting
          2. 8.3.5.1.2 Output Power Capability
        2. 8.3.5.2 Input Overvoltage Protection (OVP)
        3. 8.3.5.3 Over-Temperature Protection (TSD)
        4. 8.3.5.4 Pin-Fault Protections
        5. 8.3.5.5 VREG Pin Protection
      6. 8.3.6 DIS/FLT Pin operation
        1. 8.3.6.1 FAULT Codes
    4. 8.4 Device Functional Modes
      1. 8.4.1 UVLO Mode
      2. 8.4.2 Soft-start Mode
      3. 8.4.3 Normal Operation Mode
      4. 8.4.4 Disabled Mode
      5. 8.4.5 Fault Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 LLC Converter Operation Principle
      2. 9.2.2 Design Requirements
      3. 9.2.3 Detailed Design Procedure
      4. 9.2.4 Application Curves
    3. 9.3 What to Do and What Not to Do
  11. 10Power Supply Recommendations
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  13. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 接收文档更新通知
    3. 12.3 支持资源
    4. 12.4 Trademarks
    5. 12.5 静电放电警告
    6. 12.6 术语表
  14. 13Mechanical, Packaging, and Orderable Information

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订购信息

8.3.5.1 Overcurrent Protection

The UCC25800-Q1 transformer driver has two levels of overcurrent protection (OCP).

  • The first level (OCP1) triggers if the current through the low-side MOSFET exceeds programmed threshold IOCP during its on-time in each switching cycle for 2.1 ms. Refer to OCP Threshold Setting for OCP1 threshold programming details.
    • OCP1 detection is based on only the low-side MOSFET current, when the SW pin current flows into the SW pin
  • The second level (OCP2) triggers if the current in either the high-side or low-side MOSFET exceeds 5 × IOCP for 100 ns.
    • The OCP2 threshold is set significantly above OCP1 threshold to allow the unit to cope with heavy load surges for a short duration, or during the start-up to charge the large output capacitor. If OCP2 is exceeded, it indicates that there is a serious fault in the system. OCP2 tracks OCP1 so that events like output overload can still trip OCP2, even if the current limit is set well below the maximum current limit of the transformer driver.

  • During soft-start
    • The OCP1 is disabled
    • The OCP2 threshold is fixed at its maximum value of 5 A
  • After soft-start
    • OCP1 is enabled, with the threshold IOCP equal to the programmed value
    • OCP2 threshold becomes 5 times of the programmed IOCP level.
  • The OCP1 overcurrent timer is implemented as an up-down counter to ensure that the repetitive short over-current events as well as a sustained 2.1-ms over current trigger the OCP.
    • OCP1 overcurrent timer counts up if the SW current crosses IOCP for longer than 100 ns in each switching cycle
    • OCP1 overcurrent timer counts down if the SW current does not cross IOCP for longer than 100 ns in the entire switching cycle
    • The internal counter for OCP1 overcurrent timer counts up in 2.1 ms from 0 to the trip threshold and counts down in 180 ms from the trip threshold down to 0.
  • OCP2 detection has an analog filter which filters out pulses of less than 100 ns.

The transformer driver imposes a restart time of 100 ms before restarting from overcurrent protection to maintain the RMS current in the transformer driver below its limit. The OCP behaviors are illustrated in Figure 8-10 and Figure 8-11.

GUID-34160E41-8F8B-4310-9511-D818E7E9CF3B-low.svgFigure 8-10 OCP1 protection and recovery behavior
GUID-116BFC4C-811B-42FC-87A0-A91B578A372B-low.gifFigure 8-11 OCP2 protection and recovery behavior