SNVS397F September   2005  – December 2025 LM5005

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD 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
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 High-Voltage Start-Up Regulator
      2. 6.3.2 Shutdown and Standby
      3. 6.3.3 Oscillator and Synchronization Capability
      4. 6.3.4 Error Amplifier and PWM Comparator
      5. 6.3.5 RAMP Generator
      6. 6.3.6 Current Limit
      7. 6.3.7 Soft-Start Capability
      8. 6.3.8 MOSFET Gate Driver
    4. 6.4 Device Functional Modes
      1. 6.4.1 Shutdown Mode
      2. 6.4.2 Standby Mode
      3. 6.4.3 Light-Load Operation
      4. 6.4.4 Thermal Shutdown Protection
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Reducing Bias Power Dissipation
      2. 7.1.2 Input Voltage UVLO Protection
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1  Custom Design With WEBENCH® Tools
        2. 7.2.2.2  Frequency Set Resistor (RT)
        3. 7.2.2.3  Inductor (LF)
        4. 7.2.2.4  Ramp Capacitor (CRAMP)
        5. 7.2.2.5  Output Capacitors (COUT)
        6. 7.2.2.6  Schottky Diode (DF)
        7. 7.2.2.7  Input Capacitors (CIN)
        8. 7.2.2.8  VCC Capacitor (CVCC)
        9. 7.2.2.9  Bootstrap Capacitor (CBST)
        10. 7.2.2.10 Soft Start Capacitor (CSS)
        11. 7.2.2.11 Feedback Resistors (RFB1 and RFB2)
        12. 7.2.2.12 RC Snubber (RS and CS)
        13. 7.2.2.13 Compensation Components (RC1, CC1, CC2)
        14. 7.2.2.14 Bill of Materials
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 PCB Layout for EMI Reduction
        2. 7.4.1.2 Thermal Design
        3. 7.4.1.3 Ground Plane Design
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Third-Party Products Disclaimer
    2. 8.2 Device Support
      1. 8.2.1 Development Support
        1. 8.2.1.1 Custom Design With WEBENCH® Tools
    3. 8.3 Documentation Support
      1. 8.3.1 Related Documentation
        1. 8.3.1.1 PCB Layout Resources
        2. 8.3.1.2 Thermal Design Resources
    4. 8.4 Receiving Notification of Documentation Updates
    5. 8.5 Support Resources
    6. 8.6 Trademarks
    7. 8.7 Electrostatic Discharge Caution
    8. 8.8 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.2.2.12 RC Snubber (RS and CS)

A snubber network across the power diode reduces ringing and spikes at the switching node. Excessive ringing and spikes can cause erratic operation and couple spikes and noise to the output. Ultimately, excessive spikes beyond the rating of the LM5005 or the freewheeling diode can damage devices. Selecting the values for the snubber is best accomplished through empirical methods. First, make sure the lead lengths for the snubber connections are short. For the current levels typical of the LM5005 converter, a snubber resistance RS from 2Ω to 10Ω is adequate. Increasing the value of the snubber capacitor results in more damping but higher losses. Select a minimum value of CS that provides adequate damping of the SW voltage waveform at full load. See PCB Layout for EMI Reduction for more details.