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

Bulk Voltage Sensing

The BLK pin is used to sense the LLC DC input voltage (bulk voltage) level. The comparators on BLK pin have the following two thresholds:

  • Bulk voltage level when LLC starts switching – VBLKStart
  • Bulk voltage level when LLC stops switching – VBLKStop

A resistor divider is connected to the pin to achieve the desired system input range. A fault is triggered if BLK pin voltage drops lower than VBLKStop during operation. The detailed action of Input Under Voltage Protection is described in Input Under Voltage Protection (VINUVP) section.

Figure 33 shows the block diagram of the BLK pin.

UCC256402 UCC256403 UCC256404 Fig-02-slusd90.gifFigure 33. BLK Pin Block Diagram

BLK voltage is also used to monitor the input over voltage fault for some device versions as listed in Device Comparison Table. There are two thresholds:

  • Bulk voltage level when BLK over voltage protection (OVP) rising threshold - VBLKOVPRise
  • Bulk voltage level when BLK over voltage protection (OVP) falling threshold - VBLKOVPFall

When BLK voltage is higher than VBLKOVPRise, OVP is triggered; OVP gets cleared when BLK voltage falls below VBLKOVPFall.