SLUSDD4B April   2019  – December 2020 UC1843B-SP

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 UVLO
      2. 7.3.2 Reference
      3. 7.3.3 Totem-Pole Output
    4. 7.4 Device Functional Modes
  8. 8 Application Information Disclaimer
    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 Switching Frequency
        2. 8.2.2.2 Transformer
        3. 8.2.2.3 RCD Diode Clamp
        4. 8.2.2.4 Output Diode
        5. 8.2.2.5 Output Filter and Capacitor
        6. 8.2.2.6 Compensation
        7. 8.2.2.7 Sense Resistor and Slope Compensation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Feedback Traces
      2. 10.1.2 Input/Output Capacitors
      3. 10.1.3 Compensation Components
      4. 10.1.4 Traces and Ground Planes
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.3 Application Curves

GUID-F2824A98-8535-4F1B-A3A9-37D3D81C57B1-low.pngFigure 8-2 Switch Node of Flyback Converter

For the test in Figure 8-2, 40 V was applied to the input and 10 A was drawn from the output. Ringing can be present on the switching node if the converter is run in discontinuous conduction mode rather than the continuous conduction mode the design was run with.

GUID-016A245C-64EE-496B-AE43-C5A9A1187402-low.pngFigure 8-3 Load Step Down With 40 VIN
GUID-9422F448-04BA-44ED-869B-3A9D684D9798-low.pngFigure 8-4 Load Step Up With 40 VIN

For tests shown in and , 40 V was applied to the input and a load step was applied to the output. The load step applied was from 0 A to 10 A and 10 A to 0 A. Note that those currents do not include the 0.1-A pre-load. The curves show that the stability of the design due to the lack of ringing during the load step.