ZHCSGX8E march   2017  – june 2023 TPS61253A , TPS61253E

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Device Comparison
  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 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 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 Start-up
      2. 8.3.2 Enable and Disable
      3. 8.3.3 Undervoltage Lockout (UVLO)
      4. 8.3.4 Current Limit Operation
      5. 8.3.5 Load Disconnection
      6. 8.3.6 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Auto PFM Mode
      2. 8.4.2 Forced PWM Mode
      3. 8.4.3 Ultrasonic Mode
      4. 8.4.4 Pass-Through Mode
  10. 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 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Inductor Selection
        3. 9.2.2.3 Output Capacitor
        4. 9.2.2.4 Input Capacitor
        5. 9.2.2.5 Checking Loop Stability
        6. 9.2.2.6 Application Curves
      3. 9.2.3 System Examples
  11.   Power Supply Recommendations
  12. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  13. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 第三方产品免责声明
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 接收文档更新通知
    4. 11.4 支持资源
    5. 11.5 Trademarks
    6. 11.6 静电放电警告
    7. 11.7 术语表
  14.   Mechanical, Packaging, and Orderable Information

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8.3.1 Start-up

The TPS61253x integrates an internal circuit that controls the ramp up of the output voltage during start-up and prevents the converter from the large inrush current. When the device is enabled, the high-side rectifying switch turns on to charge the output capacitor linearly which is called the pre-charge phase. During the pre-charge phase, the output current is limited to the pre-charge current limit ILIM_DC. The pre-charge phase terminates until the output voltage getting close to the input voltage.

Once the output capacitor has been biased close to the input voltage, the device starts switching which is called the soft-start phase. During the soft start phase, there is a soft-start voltage controlling the FB pin voltage, and the output voltage rising slope follows the soft-start voltage slope. The device finishes the soft-start phase and operates normally when the nominal output voltage is reached.

Table 8-1 Start-up Mode Description
MODE DESCRIPTION CONDITION
Pre-charge VOUT linearly starts up without switching VOUT < VIN - 300 mV
Boost soft start VOUT starts up wih switching phrase VOUT_BOOST ≥ VOUT ≥ VIN - 300 mV