SLVSIO8 September   2026 TPS638221

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Control Scheme
        1. 7.3.1.1 Buck Operation
        2. 7.3.1.2 Boost Operation
        3. 7.3.1.3 Buck-Boost Operation
      2. 7.3.2 Operation Mode
        1. 7.3.2.1 PFM Operation
        2. 7.3.2.2 Forced-PWM Operation (FPWM)
        3. 7.3.2.3 Ultra-sonic Mode Operation
      3. 7.3.3 Undervoltage Lockout (UVLO)
      4. 7.3.4 Enable and Soft Start
      5. 7.3.5 Protection Functions
        1. 7.3.5.1 Input Voltage Protection (IVP)
        2. 7.3.5.2 Output Voltage Protection (OVP)
        3. 7.3.5.3 Current Limit Mode and Overcurrent Protection
        4. 7.3.5.4 Output Short Circuit Protection (Hiccup)
        5. 7.3.5.5 Thermal Shutdown
      6. 7.3.6 Power Good
      7. 7.3.7 Load Disconnect
      8. 7.3.8 Output Discharge
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 3.3V Output Power Supply
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Output Capacitor Selection
          3. 8.2.1.2.3 Input Capacitor Selection
          4. 8.2.1.2.4 Setting the Output Voltage
        3. 8.2.1.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Export Control Notice
    8. 9.8 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1.     67

7.3.8 Output Discharge

The TPS638221 provides an active pull down current to quickly discharge output when the EN pin is logic low. The output discharge function makes the power on and off sequencing smooth. Pay attention to the output discharge function if use this device in applications such as power multiplexing, because the output discharge circuitry creates a constant current path between the multiplexer output and the ground.

The TPS638221 also provides a discharge current when the VIN UVLO falling threshold is triggered and the load is not ultra-light. The discharge circuit works until VIN falls to around 1V.