SLUSG22 October   2025 UCC35131-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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 Insulation Specifications
    6. 6.6 Electrical Characteristics
    7. 6.7 Safety-Related Certifications
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Pre-Production Samples Operating Limits
    3. 7.3 Functional Block Diagram
    4. 7.4 Feature Description
      1. 7.4.1 Power Stage Operation
        1. 7.4.1.1 VDD-COM Voltage Regulation
        2. 7.4.1.2 COM-VEE Voltage Regulation
      2. 7.4.2 Output Voltage Soft Start
      3. 7.4.3 ENA and Power-Good
      4. 7.4.4 Protection Functions
        1. 7.4.4.1 Input Undervoltage Lockout
        2. 7.4.4.2 Input Overvoltage Lockout
        3. 7.4.4.3 Output Undervoltage Protection
        4. 7.4.4.4 Output Overvoltage Protection
        5. 7.4.4.5 Over-Temperature Protection
        6. 7.4.4.6 BSW Pin Faults Protection
    5. 7.5 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 VDD-COM Voltage Regulation
        2. 8.2.2.2 COM-VEE Voltage Regulation and Single Output Configuration
    3. 8.3 System Examples
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 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 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4.4.6 BSW Pin Faults Protection

UCC35131-Q1 has protection mechanism against BSW Pin faults during the soft-start period for the COM-VEE buck-boost converter.

In the case of BSW pin-open, when VDD voltage passes VVDD_UVLOS_R threshold, the part detects the first inductor current pulse width, which is the current ramp-up period until it hits the peak current limit. If the first inductor current pulse width is higher than the normal pulse width using largest inductance (>2.9μs), the BSW fault protection will be triggered to disable the buck-boost switching. Then, the device will stop switching after VDD soft start completion.

In the case of BSW pin-short to COM or VEE pin, the part detects the inductor current at the end of leading-edge-blank period. If the current is higher than the inductor peak current limit during soft-start, the BSW fault protection will be triggered to disable the buck-boost switching. Then the device will stop switching after VDD soft start completion.