SLVSFT0A July   2021  – December 2021 TPS22992

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 (VBIAS = 5 V)
    6. 7.6  Electrical Characteristics (VBIAS = 3.3 V)
    7. 7.7  Electrical Characteristics (VBIAS = 1.5 V)
    8. 7.8  Switching Characteristics (VBIAS = 5 V)
    9. 7.9  Switching Characteristics (VBIAS = 3.3 V)
    10. 7.10 Switching Characteristics (VBIAS = 1.5 V)
    11. 7.11 Typical Characteristics
  8. 8 Timing Diagram
  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 Adjustable Quick Output Discharge
      3. 9.3.3 Adjustable Slew Rate
      4. 9.3.4 Power Good (PG) Signal
      5. 9.3.5 Thermal Shutdown
      6. 9.3.6 Short Circuit Protection (TPS22992S)
    4. 9.4 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
      3. 10.2.3 Application Performance Plots
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  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

10.2.2 Detailed Design Procedure

When the switch is enabled, the output capacitance must be charged up from 0 V to the set value (5 V in this example). This charge arrives in the form of inrush current. Inrush current can be calculated using the equation below.

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.
  • dt is the rise time in VOUT during the ramp up of the output voltage when the device is enabled.

The TPS22992 offers an adjustable rise time for VOUT, allowing the user to control the inrush current during turn-on. The appropriate rise time can be calculated using the design requirements and the inrush current equation as shown below.

Equation 3. 200 mA = 47 µF × 5 V/dt
Equation 4. dt = 1175 µs

To ensure an inrush current of less than 200 mA, a CT value that yields a rise time of more than 1175 µs must be chosen. See the oscilloscope captures in the Application Performance Plots section for an example of how the CT capacitor can be used to reduce inrush current.