SLVSDO5F July   2017  – December 2021 TPS22916

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Switching Characteristics
    7. 6.7 Typical Characteristics
      1. 6.7.1 Typical Electrical Characteristics
      2. 6.7.2 Typical Switching 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 Fall Time (tFALL) and Quick Output Discharge (QOD)
      3. 8.3.3 Full-Time Reverse Current Blocking
    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
        1. 9.2.2.1 Maximum Inrush Current
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Tape and Reel Information

8.3.2 Fall Time (tFALL) and Quick Output Discharge (QOD)

The TPS22916B, TPS22916BL, TPS22916C, and TPS22916CL include a Quick Output Discharge feature. When the switch is disabled, a discharge resistor is connected between VOUT and GND. This resistor has a typical value of QOD and prevents the output from floating while the switch is disabled.

As load capacitance and load resistance increase: tFALL increases. The larger the load resistance or load capacitance is, the longer it takes to discharge the capacitor, resulting in a longer fall time.

The output fall time is determined by how quickly the load capacitance is discharged and can be found using Equation 1 .

Equation 1. tFALL = – (RDIS) × CL × ln (V10% / V90%)

Where

  • V10% is 10% of the initial output voltage
  • V90% is 90% of the initial output voltage
  • RDIS is the result of the QOD resistance in parallel with the Load Resistance RL
  • CL is the load capacitance

With the Quick Output Discharge feature, the QOD resistance is in parallel with RL. This provides a lower total load resistance as seen from the load capacitance which discharges the capacitance faster resulting in a smaller tFALL.