ZHCSJL1C September   2010  – April 2019 TPS61251

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      简化原理图
  4. 4 修订历史记录
  5. 5 说明 （续）
  6. 6 Device Options
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Current Limit Operation
      2. 9.3.2 Soft Start
      3. 9.3.3 Enable
      4. 9.3.4 Undervoltage Lockout (UVLO)
      5. 9.3.5 Power Good
      6. 9.3.6 Input Overvoltage Protection
      7. 9.3.7 Load Disconnect and Reverse Current Protection
      8. 9.3.8 Thermal Regulation
      9. 9.3.9 Thermal Shutdown
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power-Save Mode
      2. 9.4.2 Snooze Mode
      3. 9.4.3 100% Duty-Cycle Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Custom Design With WEBENCH® Tools
        2. 10.2.2.2 Output Voltage Setting
        3. 10.2.2.3 Average Input Current Limit
        4. 10.2.2.4 Maximum Output Current
        5. 10.2.2.5 Inductor Selection
        6. 10.2.2.6 Output Capacitor
        7. 10.2.2.7 Input Capacitor
        8. 10.2.2.8 Checking Loop Stability
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Consideration
  13. 13器件和文档支持
    1. 13.1 器件支持
      1. 13.1.1 第三方产品免责声明
    2. 13.2 开发支持
      1. 13.2.1 使用 WEBENCH® 工具创建定制设计
    3. 13.3 接收文档更新通知
    4. 13.4 社区资源
    5. 13.5 商标
    6. 13.6 静电放电警告
    7. 13.7 术语表
  14. 14机械、封装和可订购信息

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

9.3.5 Power Good

The device has a built-in power good function to indicate whether the output voltage has reached the programmed value and therefore the capacitor is fully charged. The power good output (PG) is set high if the feedback voltage reaches 95% of its nominal value. The power good comparator operates even in shut down mode when EN is set to low and/or VIN is turned off. This guaranties power good functionality until the capacitor is discharged. The PG output goes low when VOUT drops below 2.3 V and indicates the discharge of the capacitor. If the output voltage decreases further and goes below 2 V the converter disables all internal circuitry. Therefore the PG open drain output becomes high resistive and follows the voltage the pullup resistor is connected to.

Because power good functionality is active as long as the output capacitors are charged the converter can be disconnected from its supply but is still supplying the following circuitry with energy. A connected buck converter or buck-boost converter can use this energy to support a follow-on circuit that needs additional energy for a secured shut down.