SLLSEP9H September   2015  – July 2019 SN6505A , SN6505B

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simplified Schematic
  4. Revision History
  5. Pin Configuration and Functions
  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 Timing Requirements
    7. 6.7 Typical Characteristics, SN6505A
    8. 6.8 Typical Characteristics, SN6505B
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Push-Pull Converter
      2. 8.3.2 Core Magnetization
    4. 8.4 Device Functional Modes
      1. 8.4.1 Start-Up Mode
        1. 8.4.1.1 Soft-Start
      2. 8.4.2 Operating Mode
      3. 8.4.3 Shutdown-Mode
      4. 8.4.4 Spread Spectrum Clocking
      5. 8.4.5 External Clock Mode
  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 Drive Capability
        2. 9.2.2.2 LDO Selection
        3. 9.2.2.3 Diode Selection
        4. 9.2.2.4 Capacitor Selection
        5. 9.2.2.5 Transformer Selection
          1. 9.2.2.5.1 V-t Product Calculation
          2. 9.2.2.5.2 Turns Ratio Estimate
          3. 9.2.2.5.3 Recommended Transformers
      3. 9.2.3 Application Curves
      4. 9.2.4 System Examples
        1. 9.2.4.1 Higher Output Voltage Designs
        2. 9.2.4.2 Application Circuits
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

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 SN6505 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 RB168MM-40.

SN6505A SN6505B diode_forward_left_SLLSEP9.gifFigure 43. Diode Forward Characteristics for MBR0520L
SN6505A SN6505B diode_forward_rifgt_SLLSEP9.gifFigure 44. Diode Forward Characteristics MBR0530