SLUSG21A May   2025  – September 2025 UCC25661

PRODUCTION DATA  

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 Switching Characteristics
   7. 6.7 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 Input Power Proportional Control
         1. 7.3.1.1 Voltage Feedforward
      2. 7.3.2 VCR Synthesizer
         1. 7.3.2.1 TSET Programming
      3. 7.3.3 Feedback Chain (Control Input)
      4. 7.3.4 Adaptive Dead-Time
      5. 7.3.5 Input Voltage Sensing
         1. 7.3.5.1 Brownin and Brownout Thresholds and Options
         2. 7.3.5.2 AC Input Zero Crossing Detection
         3. 7.3.5.3 Output OVP and External OTP
      6. 7.3.6 Resonant Tank Current Sensing
   4. 7.4 Protections
      1. 7.4.1 Zero Current Switching (ZCS) Protection
      2. 7.4.2 Minimum Current Turn-off During Soft Start
      3. 7.4.3 Cycle by Cycle Current Limit and Short Circuit Protection
      4. 7.4.4 Overload (OLP) Protection
      5. 7.4.5 VCC OVP Protection
   5. 7.5 Device Functional Modes
      1. 7.5.1 Startup
         1. 7.5.1.1 With HV Start-up
            1. 7.5.1.1.1 First Time Start-up Sequence
            2. 7.5.1.1.2 Restart Sequence
         2. 7.5.1.2 Without HV Startup
      2. 7.5.2 Soft Start Ramp
         1. 7.5.2.1 Startup Transition to Regulation
      3. 7.5.3 Light Load Management
         1. 7.5.3.1 Operating Modes (Burst Pattern)
         2. 7.5.3.2 Mode Transition Management
         3. 7.5.3.3 Burst Mode Thresholds Programming
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  LLC Power Stage Requirements
         2. 8.2.2.2  LLC Gain Range
         3. 8.2.2.3  Select Ln and Qe
         4. 8.2.2.4  Determine Equivalent Load Resistance
         5. 8.2.2.5  Determine Component Parameters for LLC Resonant Circuit
         6. 8.2.2.6  LLC Primary-Side Currents
         7. 8.2.2.7  LLC Secondary-Side Currents
         8. 8.2.2.8  LLC Transformer
         9. 8.2.2.9  LLC Resonant Inductor
         10. 8.2.2.10 LLC Resonant Capacitor
         11. 8.2.2.11 LLC Primary-Side MOSFETs
         12. 8.2.2.12 Design Considerations for Adaptive Dead-Time
         13. 8.2.2.13 LLC Rectifier Diodes
         14. 8.2.2.14 LLC Output Capacitors
         15. 8.2.2.15 HV Pin Series Resistors
         16. 8.2.2.16 BLK Pin Voltage Divider
         17. 8.2.2.17 ISNS Pin Differentiator
         18. 8.2.2.18 TSET Pin
         19. 8.2.2.19 OVP/OTP Pin
         20. 8.2.2.20 Burst Mode Programming
      3. 8.2.3 Application Curves
   3. 8.3 Power Supply Recommendations
      1. 8.3.1 VCCP Pin Capacitor
      2. 8.3.2 Boot Capacitor
      3. 8.3.3 V5P Pin Capacitor
   4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
         1. 8.4.2.1 Schematics
10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
11. 10Revision History
12. 11Mechanical, Packaging, and Orderable Information

UCC25661 750kHz Wide V_IN/V_OUT Range LLC Controller Optimized for Light-Load Efficiency