JAJSHI0I February   2012  – January 2021 SN6501

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 説明
    1.     Revision History
  4. 4 Pin Configuration and Functions
  5. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 Handling Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  6. 6 Parameter Measurement Information
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Push-Pull Converter
      2. 7.3.2 Core Magnetization
    4. 7.4 Device Functional Modes
      1. 7.4.1 Start-Up Mode
      2. 7.4.2 Operating Mode
      3. 7.4.3 Off-Mode
  8. 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 SN6501 Drive Capability
        2. 8.2.2.2 LDO Selection
        3. 8.2.2.3 Diode Selection
        4. 8.2.2.4 Capacitor Selection
        5. 8.2.2.5 Transformer Selection
          1. 8.2.2.5.1 V-t Product Calculation
          2. 8.2.2.5.2 Turns Ratio Estimate
          3. 8.2.2.5.3 Recommended Transformers
      3. 8.2.3 Application Curve
      4. 8.2.4 Higher Output Voltage Designs
      5. 8.2.5 Application Circuits
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 サード・パーティ製品に関する免責事項
    2. 11.2 Trademarks
    3. 11.3 静電気放電に関する注意事項
    4. 11.4 用語集
  12. 12Mechanical, Packaging, and Orderable Information

8.2.2.3 Diode Selection

A rectifier diode should always possess low-forward voltage to provide as much voltage to the converter output as possible. When used in high-frequency switching applications, such as the SN6501 however, the diode must also possess a short recovery time. Schottky diodes meet both requirements and are therefore strongly recommended in push-pull converter designs. A good choice for low-volt applications and ambient temperatures of up to 85°C is the low-cost Schottky rectifier MBR0520L with a typical forward voltage of 275 mV at 100-mA forward current. For higher output voltages such as ±10 V and above use the MBR0530 which provides a higher DC blocking voltage of 30 V.

Lab measurements have shown that at temperatures higher than 100°C the leakage currents of the above Schottky diodes increase significantly. This can cause thermal runaway leading to the collapse of the rectifier output voltage. Therefore, for ambient temperatures higher than 85°C use low-leakage Schottky diodes, such as RB168M-40.

GUID-A2A9DDFA-BA85-4CF9-9A59-276F135C88F5-low.gifFigure 8-4 Diode Forward Characteristics for MBR0520L (Left) and MBR0530 (Right)