SNVSCJ3 December   2023 LMR66410 , LMR66420 , LMR66430

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 System Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Enable, Start-Up, and Shutdown
      2. 7.3.2  External CLK SYNC (With MODE/SYNC)
        1. 7.3.2.1 Pulse-Dependent MODE/SYNC Pin Control
      3. 7.3.3  Adjustable Switching Frequency (with RT)
      4. 7.3.4  Power-Good Output Operation
      5. 7.3.5  Internal LDO, VCC, and VOUT/FB Input
      6. 7.3.6  Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
      7. 7.3.7  Output Voltage Selection
      8. 7.3.8  Spread Spectrum
      9. 7.3.9  Soft Start and Recovery from Dropout
        1. 7.3.9.1 Recovery from Dropout
      10. 7.3.10 Current Limit and Short Circuit
      11. 7.3.11 Thermal Shutdown
      12. 7.3.12 Input Supply Current
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
        1. 7.4.3.1 CCM Mode
        2. 7.4.3.2 Auto Mode – Light Load Operation
          1. 7.4.3.2.1 Diode Emulation
          2. 7.4.3.2.2 Frequency Reduction
        3. 7.4.3.3 FPWM Mode – Light Load Operation
        4. 7.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 7.4.3.5 Dropout
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Synchronous Buck Regulator at 400 kHz
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1  Choosing the Switching Frequency
        2. 8.2.3.2  Setting the Output Voltage
          1. 8.2.3.2.1 VOUT / FB for Adjustable Output
        3. 8.2.3.3  Inductor Selection
        4. 8.2.3.4  Output Capacitor Selection
        5. 8.2.3.5  Input Capacitor Selection
        6. 8.2.3.6  CBOOT
        7. 8.2.3.7  VCC
        8. 8.2.3.8  CFF Selection
        9. 8.2.3.9  External UVLO
        10. 8.2.3.10 Maximum Ambient Temperature
      4. 8.2.4 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Ground and Thermal Considerations
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Device Nomenclature
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1 Synchronous Buck Regulator at 400 kHz

The following figure shows the schematic diagram of a synchronous buck regulator with an output voltage set at 5 V and a rated load current of 3 A. The RT resistor of 39.2 kΩ sets the switching frequency at 400 kHz.

In this example, the nominal input voltage is 12 V and ranges from 7 V to 36 V. The VOUT / FB pin is connected directly to the output voltage net which helps improve efficiency, particularly at light loads.

GUID-20240108-SS0I-QTRR-P35N-NMWD8GNGQ4X1-low.svg Figure 8-1 Application Circuit - 5 V (Fixed), 3 A, 400 kHz