ZHCSGK9B April   2017  – December 2017 TPS22971

PRODUCTION DATA.  

  1. 特性
  2. 应用
  3. 说明
    1.     Device Images
      1.      典型应用
  4. 修订历史记录
  5. Pin Configuration and Functions
    1.     Pin Functions
  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 DC Characteristics
    8. 6.8 Typical AC Characteristics
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 On and Off Control
      2. 8.3.2 Controlled Turn-On
      3. 8.3.3 Power Good (PG)
      4. 8.3.4 Quick Output Discharge (QOD)
    4. 8.4 Device Functional Modes
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Thermal Consideration
      2. 9.1.2 PG Pull Up Resistor
      3. 9.1.3 Power Sequencing
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Maximum Voltage Drop and On-Resistance
        2. 9.2.2.2 Managing Inrush Current
      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 文档支持
      1. 12.1.1 相关文档
    2. 12.2 接收文档更新通知
    3. 12.3 社区资源
    4. 12.4 商标
    5. 12.5 静电放电警告
    6. 12.6 Glossary
  13. 13机械、封装和可订购信息

Managing Inrush Current

When the switch is enabled, the output capacitors must be charged up from 0 V to VIN. This charge arrives in the form of inrush current. Given a load capacitance (CL) of 33 μF, an input voltage (VIN) of 3.6V and a maximum inrush (IINRUSH) of 630 mA, use Equation 12 and Equation 13 to solve for Slew Rate (SR).

Equation 12. TPS22971 tps22971x-equation-12.gif
Equation 13. TPS22971 tps22971x-equation-13.gif

Now that the desired slew rate has been calculated, use SR and VIN in in Equation 14 to calculate a CT capacitance value.

Equation 14. TPS22971 tps22971x-equation-14.gif

A capacitance value of 1007pF is a non-standard value therefore a 1000 pF CT capacitance is used moving forward.

The calculated CT value can be used with Equation 2 and Equation 4 to determine tON and tPG,ON, respectively as shown in Equation 15 and Equation 16.

Equation 15. TPS22971 tps22971x-equation-15.gif
Equation 16. TPS22971 tps22971x-equation-16.gif