JAJSOG6 October   2022 TPS568231

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
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  PWM Operation and D-CAP3™ Control Mode
      2. 7.3.2  Eco-mode™ Control
      3. 7.3.3  4.7-V LDO
      4. 7.3.4  MODE Selection
      5. 7.3.5  Soft Start and Prebiased Soft Start
      6. 7.3.6  Enable and Adjustable UVLO
      7. 7.3.7  Power Good
      8. 7.3.8  Overcurrent Protection and Undervoltage Protection
      9. 7.3.9  UVLO Protection
      10. 7.3.10 Thermal Shutdown
      11. 7.3.11 Output Voltage Discharge
    4. 7.4 Device Functional Modes
      1. 7.4.1 Light Load Operation
      2. 7.4.2 Standby Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 External Component Selection
          1. 8.2.2.1.1 Output Voltage Set Point
          2. 8.2.2.1.2 Switching Frequency and MODE Selection
          3. 8.2.2.1.3 Inductor Selection
          4. 8.2.2.1.4 Output Capacitor Selection
          5. 8.2.2.1.5 Input Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 サポート・リソース
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, 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

7.3.5 Soft Start and Prebiased Soft Start

The TPS568231 has an internal 1.2-ms soft-start time and an external adjustable soft-start time that can be set by connecting a capacitor on the SS pin. When the EN pin becomes high, the soft-start charge current (ISS) begins charging the external capacitor (CSS) connected between SS and AGND. The device tracks the lower of the internal soft-start voltage or the external soft-start voltage as the reference. Equation 3 is the equation for the soft-start time (tSS):

Equation 3. GUID-67A7A23B-689F-4657-8213-D6AE4557E60D-low.gif

where

  • VREF is 0.6 V and ISS is 6 µA.

If the output capacitor is prebiased at start-up, the device initiates switching and starts ramping up only after the internal reference voltage becomes greater than the feedback voltage VFB. This scheme ensures that the converters ramp up smoothly into regulation point.