JAJSKE1 October   2021 LM61430-Q1

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Characteristics
    7. 7.7 Systems Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  EN/SYNC Uses for Enable and VIN UVLO
      2. 8.3.2  EN/SYNC Pin Uses for Synchronization
      3. 8.3.3  Clock Locking
      4. 8.3.4  Adjustable Switching Frequency
      5. 8.3.5  PGOOD Output Operation
      6. 8.3.6  Internal LDO, VCC UVLO, and BIAS Input
      7. 8.3.7  Bootstrap Voltage and VCBOOT-UVLO (CBOOT Pin)
      8. 8.3.8  Adjustable SW Node Slew Rate
      9. 8.3.9  Spread Spectrum
      10. 8.3.10 Soft Start and Recovery From Dropout
      11. 8.3.11 Output Voltage Setting
      12. 8.3.12 Overcurrent and Short Circuit Protection
      13. 8.3.13 Thermal Shutdown
      14. 8.3.14 Input Supply Current
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
        1. 8.4.3.1 Auto Mode - Light-Load Operation
          1. 8.4.3.1.1 Diode Emulation
          2. 8.4.3.1.2 Frequency Reduction
        2. 8.4.3.2 FPWM Mode - Light-Load Operation
          1. 8.4.3.2.1 CCM Mode
        3. 8.4.3.3 Minimum On Time (High Input Voltage) Operation
        4. 8.4.3.4 Dropout
  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  Choosing the Switching Frequency
        2. 9.2.2.2  Setting the Output Voltage
        3. 9.2.2.3  Inductor Selection
        4. 9.2.2.4  Output Capacitor Selection
        5. 9.2.2.5  Input Capacitor Selection
        6. 9.2.2.6  BOOT Capacitor
        7. 9.2.2.7  BOOT Resistor
        8. 9.2.2.8  VCC
        9. 9.2.2.9  BIAS
        10. 9.2.2.10 CFF and RFF Selection
        11. 9.2.2.11 External UVLO
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Ground and Thermal Considerations
    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 Receiving Notification of Documentation Updates
    4. 12.4 サポート・リソース
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.4.3.1 Auto Mode - Light-Load Operation

The LM61430-Q1 can have two behaviors while lightly loaded. One behavior, called AUTO mode operation, allows for seamless transition between normal current mode operation while heavily loaded and highly efficient light load operation. The other behavior, called FPWM Mode, maintains full frequency even when unloaded. Which mode the LM61430-Q1 operates in depends on which factory option is employed; see Section 5. Note that all parts operate in FPWM mode when synchronizing frequency to an external signal.

In auto mode, light load operation is employed in the LM61430-Q1 at load lower than approximately a tenth of the rated maximum output current. Light-load operation employs two techniques to improve efficiency:

  • Diode emulation, which allows DCM operation
  • Frequency reduction

Note that while these two features operate together to create excellent light load behavior, they operate independently of each other.