ZHCSHW4A December   2017  – January 2019 TPS23523

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 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Relationship between Sense Voltage, Gate Current, and Timer
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Current Limit
        1. 8.3.1.1 Programming the CL Switch-Over Threshold
        2. 8.3.1.2 Setting Up the PROG Pin
        3. 8.3.1.3 Programming CL1
        4. 8.3.1.4 Programming CL2
      2. 8.3.2 Soft Start Disconnect
      3. 8.3.3 Timer
      4. 8.3.4 Gate 2
      5. 8.3.5 OR-ing
    4. 8.4 Device Functional Modes
      1. 8.4.1 OFF State
      2. 8.4.2 Insertion Delay State
      3. 8.4.3 Start-up State
      4. 8.4.4 Normal Operation State
  9. 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  Selecting RSNS
        2. 9.2.2.2  Selecting Soft Start Setting: CSS and CSS,VEE
        3. 9.2.2.3  Selecting VDS Switch Over Threshold
        4. 9.2.2.4  Timer Selection
        5. 9.2.2.5  MOSFET Selection and SOA Checks
        6. 9.2.2.6  Input Cap, Input TVS, and OR-ing FET selection
        7. 9.2.2.7  EMI Filter Consideration
        8. 9.2.2.8  Undervoltage and Overvoltage Settings
        9. 9.2.2.9  Choosing RVCC and CVCC
        10. 9.2.2.10 Power Good Interface to Downstream DC/DC
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12器件和文档支持
    1. 12.1 器件支持
      1. 12.1.1 第三方产品免责声明
    2. 12.2 文档支持
      1. 12.2.1 相关文档
    3. 12.3 接收文档更新通知
    4. 12.4 社区资源
    5. 12.5 商标
    6. 12.6 静电放电警告
    7. 12.7 术语表
  13. 13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

9.2.2.2 Selecting Soft Start Setting: CSS and CSS,VEE

First, compute the minimum inrush current where the timer will trip using equation below.

Equation 12. TPS23523 equation-02-slvsdf9.gif

To avoid running the timer the inrush current needs to be sufficiently low. Target 0.4 A of inrush current to allow margin, and compute the target CSS using equation below.

Equation 13. TPS23523 tps23523_equation13.gif

Next choose, the next available CSS greater than 39.6 nF. For this example 43 nF was used, which assumes a 33 nF and 10 nF cap in parallel. This results in an inrush current of 0.37 A at max COUT (792 µF) and inrush current of 0.31 A at typical COUT (660 µF). Also it is recommended to add a capacitor between the soft start pin and VEE (CSS,VEE) to improve immunity to input voltage noise during soft start. It's recommended to chose a capacitor that's 3x larger than CSS. In this case a 150 nF capacitor was chosen.

Finally the start-up time at maximum input voltage can be computed using the equation below:

Equation 14. TPS23523 tps23523_equation14.gif