SLUSD90C June   2019  – March 2020 UCC256402 , UCC256403 , UCC256404

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Simplified Schematic
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Hybrid Hysteretic Control
      2. 8.3.2 Regulated 13-V Supply
      3. 8.3.3 Feedback Chain
        1. 8.3.3.1 Optocoupler Feedback Signal Input and Bias
        2. 8.3.3.2 FB Pin Voltage Clamp
        3. 8.3.3.3 "Pick Lower Value" Block and Soft Start Multiplexer
        4. 8.3.3.4 Pick Higher Block and Burst Mode Multiplexer
        5. 8.3.3.5 VCR Comparators
      4. 8.3.4 Resonant Capacitor Voltage Sensing
      5. 8.3.5 Resonant Current Sensing
      6. 8.3.6 Bulk Voltage Sensing
      7. 8.3.7 Output Voltage Sensing
      8. 8.3.8 High Voltage Gate Driver
        1. 8.3.8.1 Adaptive Dead Time Control
      9. 8.3.9 Protections
        1. 8.3.9.1 ZCS Region Prevention
        2. 8.3.9.2 Over Current Protection (OCP)
        3. 8.3.9.3 Bias Winding Over Voltage Protection (BWOVP)
        4. 8.3.9.4 Input Under Voltage Protection (VINUVP)
        5. 8.3.9.5 Input Over Voltage Protection (VINOVP)
        6. 8.3.9.6 Boot UVLO
        7. 8.3.9.7 RVCC UVLO
        8. 8.3.9.8 Over Temperature Protection (OTP)
    4. 8.4 Device Functional Modes
      1. 8.4.1 High Voltage Start-Up
      2. 8.4.2 X-Capacitor Discharge
      3. 8.4.3 Burst Mode Control
        1. 8.4.3.1 Soft-Start and Burst-Mode Threshold
        2. 8.4.3.2 BMTL/BMTH Ratio Programming
      4. 8.4.4 System State Machine
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  LLC Power Stage Requirements
        2. 9.2.2.2  LLC Gain Range
        3. 9.2.2.3  Select Ln and Qe
        4. 9.2.2.4  Determine Equivalent Load Resistance
        5. 9.2.2.5  Determine Component Parameters for LLC Resonant Circuit
        6. 9.2.2.6  LLC Primary-Side Currents
        7. 9.2.2.7  LLC Secondary-Side Currents
        8. 9.2.2.8  LLC Transformer
        9. 9.2.2.9  LLC Resonant Inductor
        10. 9.2.2.10 LLC Resonant Capacitor
        11. 9.2.2.11 LLC Primary-Side MOSFETs
        12. 9.2.2.12 LLC Rectifier Diodes
        13. 9.2.2.13 LLC Output Capacitors
        14. 9.2.2.14 HV Pin Series Resistors
        15. 9.2.2.15 BLK Pin Voltage Divider
        16. 9.2.2.16 ISNS Pin Differentiator
        17. 9.2.2.17 VCR Pin Capacitor Divider
        18. 9.2.2.18 BW Pin Voltage Divider
        19. 9.2.2.19 Soft Start and Burst Mode Programming
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 VCC Pin Capacitor
    2. 10.2 Boot Capacitor
    3. 10.3 RVCC Pin Capacitor
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

LLC Transformer

A bias winding is needed in order to utilize the HV self start up function. It is recommended to design the bias winding so that the VCC voltage is greater than 13 V.

The transformer can be built or purchased according to these specifications:

  • Turns ratio: Primary : Secondary : Bias = 33 : 2 : 3
  • Primary terminal voltage: 450 Vac
  • Primary magnetizing inductance: LM = 510 µH
  • Primary side winding rated current: IR = 1.367 A
  • Secondary terminal voltage: 36 Vac
  • Secondary winding rated current: IWS = 12.959 A
  • Minimum switching frequency: 69.8 kHz
  • Maximum switching frequency: 99.7 kHz
  • Insulation between primary and secondary sides: IEC60950 reinforced insulation

The minimum operating frequency during normal operation is calculated above. Please note that for some applications that operate as a wide input LLC where the PFC may be shut off in standby mode, the operating frequency may be much lower during heavy load shutdown and the LLC can operate at just above the ZCS boundary which is a lower frequency. The magnetic components in the resonant circuit, the transformer and resonant inductor, should be rated to operate at this lower frequency.