SLUS161F April   1999  – May 2020 UCC2813-0 , UCC2813-1 , UCC2813-2 , UCC2813-3 , UCC2813-4 , UCC2813-5 , UCC3813-0 , UCC3813-1 , UCC3813-2 , UCC3813-3 , UCC3813-4 , UCC3813-5

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Block Diagram
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 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 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Detailed Pin Descriptions
        1. 8.3.1.1 COMP
        2. 8.3.1.2 CS
        3. 8.3.1.3 FB
        4. 8.3.1.4 GND
        5. 8.3.1.5 OUT
        6. 8.3.1.6 RC
        7. 8.3.1.7 REF
        8. 8.3.1.8 VCC
      2. 8.3.2  Undervoltage Lockout (UVLO)
      3. 8.3.3  Self-Biasing, Active Low Output
      4. 8.3.4  Reference Voltage
      5. 8.3.5  Oscillator
      6. 8.3.6  Synchronization
      7. 8.3.7  PWM Generator
      8. 8.3.8  Minimum Off-Time Adjustment (Dead-Time Control)
      9. 8.3.9  Leading Edge Blanking
      10. 8.3.10 Minimum Pulse Width
      11. 8.3.11 Current Limiting
      12. 8.3.12 Overcurrent Protection and Full-Cycle Restart
      13. 8.3.13 Soft Start
      14. 8.3.14 Slope Compensation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation
      2. 8.4.2 UVLO Mode
      3. 8.4.3 Soft-Start Mode
      4. 8.4.4 Fault Mode
  9. 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  Bulk Capacitor Calculation
        2. 9.2.2.2  Transformer Design
        3. 9.2.2.3  MOSFET and Output Diode Selection
        4. 9.2.2.4  Output Capacitor Calculation
        5. 9.2.2.5  Current Sensing Network
        6. 9.2.2.6  Gate Drive Resistor
        7. 9.2.2.7  REF Bypass Capacitor
        8. 9.2.2.8  RT and CT
        9. 9.2.2.9  Start-Up Circuit
        10. 9.2.2.10 Voltage Feedback Compensation Procedure
          1. 9.2.2.10.1 Power Stage Gain, Zeroes, and Poles
          2. 9.2.2.10.2 Compensating the Loop
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  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

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • D|8
  • PW|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.14 Slope Compensation

Slope compensation can be added in all current-mode control applications to cancel the peak-to-average current error. Slope compensation is necessary in applications with duty-cycles exceeding 50%, but also improves performance in those below 50%. Primary current is sensed using resistor RCS in series with the converter switch. The timing resistor can be broken up into two series resistors to bias up an NPN voltage-follower, as shown in Figure 32. This is required to provide ample compliance for slope compensation at the beginning of a switching cycle, especially with continuous-current converters. The voltage follower drives the slope compensating programming resistor (RSC) to provide a slope-compensating current into CF.

UCC2813-0 UCC2813-1 UCC2813-2 UCC2813-3 UCC2813-4 UCC2813-5 UCC3813-0 UCC3813-1 UCC3813-2 UCC3813-3 UCC3813-4 UCC3813-5 u133-24.gifFigure 32. Adding Slope Compensation