JAJSO40 December   2022 TPS22997

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 Pin Configuration and 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 (VBIAS = 5 V)
    6. 6.6  Electrical Characteristics (VBIAS = 3.3 V)
    7. 6.7  Electrical Characteristics (VBIAS = 1.5 V)
    8. 6.8  Switching Characteristics (VBIAS = 5 V)
    9. 6.9  Switching Characteristics (VBIAS = 3.3 V)
    10. 6.10 Switching Characteristics (VBIAS = 1.5 V)
    11. 6.11 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 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 Adjustable Slew Rate
      3. 8.3.3 Adjustable Quick Output Discharge
      4. 8.3.4 Thermal Shutdown
      5. 8.3.5 Power Good (PG) Signal
    4. 8.4 Device Functional Modes
  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
      3. 9.2.3 Application Performance Plots
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 ドキュメントの更新通知を受け取る方法
    2. 10.2 サポート・リソース
    3. 10.3 Trademarks
    4. 10.4 静電気放電に関する注意事項
    5. 10.5 用語集
  11. 11Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9.2.2 Detailed Design Procedure

When the switch enables, the charge up the output capacitance from 0 V to the set value (1.8 V in this example). This charge arrives in the form of inrush current. Calculate inrush current using Equation 2.

Equation 2. Inrush Current = CL × dVOUT/dt

Where:

  • CL is the output capacitance.
  • dVOUT is the change in VOUT during the ramp up of the output voltage when device is enabled. Because rise time is 10% of VOUT to 90% of VOUT, this is 80% of the VIN value.
  • dt is the rise time in VOUT during the ramp up of the output voltage when the device is enabled.

The TPS22997 offers an adjustable rise time for VOUT, allowing the user to control the inrush current during turn on. Calculate the appropriate rise time using the design requirements and the inrush current equation as shown below.

Equation 3. 1.5 A = 220 µF × (5.0 V × 80%) / dt
Equation 4. dt = 586 us

To ensure an inrush current of less than 1.5 A, a CT setting that yields a rise time of more than 586 µs must be chosen. By using a 1000pF capacitance, a rise time of 819 μs is selected, limiting the inrush current to below 1.5 A.