SLVSDW8B September   2017  – December 2021 TPS22917

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
      1. 7.7.1 Typical Electrical Characteristics
      2. 7.7.2 Typical Switching Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Test Circuit and Timing Waveforms Diagrams
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 On and Off Control
      2. 9.3.2 Turn-On Time (tON) and Adjustable Slew Rate (CT)
      3. 9.3.3 Fall Time (tFALL) and Quick Output Discharge (QOD)
        1. 9.3.3.1 QOD When System Power is Removed
    4. 9.4 Full-Time Reverse Current Blocking
    5. 9.5 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Limiting Inrush Current
        2. 10.2.2.2 Application Curves
        3. 10.2.2.3 Setting Fall Time for Shutdown Power Sequencing
        4. 10.2.2.4 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
    3. 12.3 Thermal Considerations
  13. 13Device and Documentation Support
    1. 13.1 Receiving Notification of Documentation Updates
    2. 13.2 Support Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10.2.2.3 Setting Fall Time for Shutdown Power Sequencing

Microcontrollers and processors often have a specific shutdown sequence in which power must be removed. Using the adjustable Quick Output Discharge function of the TPS22917x, adding a load switch to each power rail can be used to manage the power down sequencing. To determine the QOD values for each load switch, first confirm the power down order of the device you wish to power sequence. Be sure to check if there are voltage or timing margins that must be maintained during power down.

After the required fall time is determined, the maximum external discharge resistance (RDIS) value can be found using Equation 4:

Equation 8. tFALL = 2.2 × (RDIS || RL) × CL
Equation 9. RDIS = 630 Ω

Equation 3 can then be used to calculate the RQOD resistance needed to acheive a particular discharge value:

Equation 10. RDIS = QOD + RQOD
Equation 11. RQOD = 480 Ω

To ensure a fall time greater than, choose an RQOD value greater than 480 Ω.