SLUS846D September   2008  – August 2024 UCC25600

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  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 Soft Start
      2. 7.3.2 Overcurrent Protection
      3. 7.3.3 Gate Driver
      4. 7.3.4 Overtemperature Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Burst-Mode Operation
      2. 7.4.2 VCC
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Principal of Operation
      2. 8.1.2 Adjustable Dead Time
      3. 8.1.3 Oscillator
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Support Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
  13. 12Glossary
  14. 13Mechanical, Packaging, and Orderable Information

8.1.2 Adjustable Dead Time

Resonant half-bridge converter relies on the resonant tank current at MOSFETs turn-off to achieve soft switching and reduce switching loss. Higher turn-off current provides more energy to discharge the junction capacitor, while it generates more turn-off loss. Smaller turn-off current reduces turn-off loss, but it requires longer time to discharge MOSFETs junction capacitors and achieve soft switching. By choosing an appropriate dead time, turn-off current is minimized while still maintaining zero-voltage switching, and best system performance is realized.

In UCC25600, dead time can be adjusted through a single resistor from the DT pin to ground. With internal 2.25-V voltage reference, the current flow through the resistor sets the dead time.

Equation 17. UCC25600

To prevent shoot through when the DT pin accidentally connects to ground, a minimum 120-ns dead time is inserted into the 2 gate driver outputs. Any dead-time setting less than 120 ns will be limited to 120 ns.