SLLSFM0A March   2022  – June 2022 SN6507

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 Switching Characteristics
    7. 6.7 Typical Characteristics, SN6507
  7. 7 Parameter Measurement Information
  8. 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
      3. 8.3.3 Duty Cycle Control
      4.      Programmable Switching Frequency
      5. 8.3.4 Spread Spectrum Clocking
      6. 8.3.5 Slew Rate Control
      7. 8.3.6 Protection Features
        1. 8.3.6.1 Over Voltage Protection (OVP)
        2. 8.3.6.2 Over Current and Short Circuit Protection (OCP)
        3. 8.3.6.3 Under Voltage Lock-Out (UVLO)
        4. 8.3.6.4 Thermal Shut Down (TSD)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Start-Up Mode
        1. 8.4.1.1 Soft-Start
      2. 8.4.2 Operation Mode
      3. 8.4.3 Shutdown Mode
      4. 8.4.4 SYNC 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 Pin Configuration
        2. 9.2.2.2 LDO Selection
        3. 9.2.2.3 Diode Selection
        4. 9.2.2.4 Capacitor and Inductor 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
        6. 9.2.2.6 Low-Emissions Designs
      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 Commercially-Available Transformers
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Community Resources
    4. 10.4 Trademarks
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.2.5.1 V-t Product Calculation

To prevent a transformer from saturation its V-t product must be greater than the maximum V-t product applied by the device: the maximum time this voltage is applied to the primary for half the period of the lowest frequency at the specified input voltage. For designs using duty cycle control, the maximum V-t applied by the device can be calculated by the typical voltage applied for one quarter of the period of the lowest switching frequency. For systems using a clock frequency set by RCLK, fmin can be estimated as 15% below the typical or approximate switching frequency value, fSW, for the corresponding RCLK from Section 8.3.4. For systems where the CLK pin is connected to GND, the minimum specified FSW from Section 6 should be used. Therefore, the transformer’s minimum V-t product is determined through Equation 9 for fixed inputs and Equation 10 for wide-ranging inputs using duty cycle control:

Equation 9. Vtmin≥VIN(max)×Tmax2=VIN(max)2×fmin
Equation 10. Vtmin≥VIN(typ)×Tmax4=VIN(typ)4×fmin

Example of Fixed Input:

For a fixed input system with fSW(min) of 780 kHz and a VIN = 24 V supply with ±10 % tolerance, Equation 9 yields the minimum V-t product of:

Equation 11. Vtmin≥26.4V2×780kHz=16.9 Vμs

Example of Wide-Ranging Input:

Taking the assumption of fSW(min) as 780 kHz with a VIN(typ) 24 V supply, Equation 10 yields the minimum V-t product of:

Equation 12. Vtmin≥24V4×780kHz=7.7 Vμs

While Vt-wise all of these transformers can be driven by the device, other important factors such as isolation voltage, transformer wattage, and turns ratio must be considered before making the final decision.