SNVS686L March   2011  – June 2025 LMZ22005

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 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 Synchronization Input
      2. 6.3.2 Output Overvoltage Protection
      3. 6.3.3 Current Limit
      4. 6.3.4 Thermal Protection
      5. 6.3.5 Prebiased Start-Up
    4. 6.4 Device Functional Modes
      1. 6.4.1 Discontinuous And Continuous Conduction Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    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 Design Steps
        3. 7.2.2.3 Enable Divider, RENT, RENB, and RENH Selection
        4. 7.2.2.4 Output Voltage Selection
        5. 7.2.2.5 Soft-start Capacitor Selection
        6. 7.2.2.6 Tracking Supply Divider Option
        7. 7.2.2.7 CO Selection
        8. 7.2.2.8 CIN Selection
        9. 7.2.2.9 Discontinuous and Continuous Conduction Modes Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Examples
      3. 7.4.3 Power Dissipation and Thermal Considerations
      4. 7.4.4 Power Module SMT Guidelines
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 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

7.2.2.9 Discontinuous and Continuous Conduction Modes Selection

The approximate formula for determining the DCM/CCM boundary is as follows:

Equation 13. IDCB ≊ VO × (VIN– VO) / (2 × 3.3 μH × fSW(CCM) × VIN)

The inductor internal to the module is 3.3 μH. This value was chosen as a good balance between low and high input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple current (ILR). ILR can be calculated with:

Equation 14. ILR P-P = VO× (VIN– VO) / (3.3 µH × fSW × VIN)

where

  • VIN is the maximum input voltage
  • And fSW is typically 812 kHz.

If the output current IO is determined by assuming that IO = IL, the higher and lower peak of ILR can be determined.