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

7.3.2.3 Ultra-sonic Mode Operation

During PFM operation, the time between switching changes with the operating conditions. Because the ceramic capacitors typically used with the device are piezoelectric, certain operating conditions can cause audible noise. The device has an ultra-sonic mode feature that forces the frequency of the switching to be outside the audible range. Note that the power conversion efficiency of the device can be slightly reduced when the ultra-sonic mode is enabled at light load.

To enable ultra-sonic mode, make the MODE pin floating.