ZHCSSC1B June   2015  – December 2024 LV14240

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Fixed Frequency Peak Current Mode Control
      2. 6.3.2  Slope Compensation
      3. 6.3.3  Low Dropout Operation and Bootstrap Voltage (BOOT)
      4. 6.3.4  Adjustable Output Voltage
      5. 6.3.5  Enable and Adjustable Undervoltage Lockout
      6. 6.3.6  External Soft Start
      7. 6.3.7  Switching Frequency and Synchronization (RT/SYNC)
      8. 6.3.8  Overcurrent and Short-Circuit Protection
      9. 6.3.9  Overvoltage Protection
      10. 6.3.10 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Pulse Skipping Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Output Voltage Set-Point
        2. 7.2.2.2 Switching Frequency
        3. 7.2.2.3 Output Inductor Selection
        4. 7.2.2.4 Output Capacitor Selection
        5. 7.2.2.5 Schottky Diode Selection
        6. 7.2.2.6 Input Capacitor Selection
        7. 7.2.2.7 Bootstrap Capacitor Selection
        8. 7.2.2.8 Soft-Start Capacitor Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 接收文档更新通知
    2. 8.2 支持资源
    3. 8.3 Trademarks
    4. 8.4 静电放电警告
    5. 8.5 术语表
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.6 External Soft Start

The LV14240 has soft-start pin for programmable output ramp up time. The soft-start feature is used to prevent inrush current impacting the LV14240 and the load when power is first applied. The soft-start time can be programed by connecting an external capacitor CSS from SS pin to GND. An internal current source (typically ISS = 3 μA) charges CSS and generates a ramp from 0 V to VREF. The soft-start time can be calculated by Equation 4:

Equation 4. LV14240

The internal soft-start resets while the device is disabled or in thermal shutdown.