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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10 Power Supply Recommendations

The UCC25800-Q1 transformer driver drives an LLC converter with constant switching frequency to make the LLC converter operate near its resonant frequency. When LLC converter operates at its resonant frequency, the impedance of the resonant tank is equal to zero. The input and output voltages are virtually connected together, through the transformer turns-ratio. Given the LLC converter is a half-bridge converter, the transformer primary side only sees half of the input voltage. If the secondary side uses voltage double rectifier, it also only sees half of the output voltage. The relationship between the input and output voltages is simply the transformer turns-ratio.

Given that, to achieve a fixed output voltage, the input voltage needs to be fixed. Even though the transformer driver is recommended to operate with an input voltage source between 9 V and 34 V, it is meant to be one fixed voltage within this voltage range. Because the relationship between input and output voltages is simply the transformer turns-ratio, the accuracy of the input would impact the accuracy of the output. There is no requirement from the transformer driver, while the input voltage accuracy is demanded by the output voltage requirements.

When the input voltage is very close to 9 V (because it is very close to the UVLO threshold UVLOF) sufficient input bypass capacitor is recommended to ensure the load transient does not cause the VCC voltage drops below UVLO threshold UVLOF.