JAJSIW6E March   2020  – April 2022 LM62440-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 概要 (続き)
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Characteristics
    7. 8.7 Systems Characteristics
    8. 8.8 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  EN Uses for Enable and VIN UVLO
      2. 9.3.2  MODE/SYNC Pin Operation
        1. 9.3.2.1 Level-Dependent MODE/SYNC Pin Control
        2. 9.3.2.2 Pulse-Dependent MODE/SYNC Pin Control
        3. 9.3.2.3 Clock Locking
      3. 9.3.3  PGOOD Output Operation
      4. 9.3.4  Internal LDO, VCC UVLO, and BIAS Input
      5. 9.3.5  Bootstrap Voltage and VCBOOT-UVLO (CBOOT Pin)
      6. 9.3.6  Adjustable SW Node Slew Rate
      7. 9.3.7  Spread Spectrum
      8. 9.3.8  Soft Start and Recovery From Dropout
      9. 9.3.9  Output Voltage Setting
      10. 9.3.10 Overcurrent and Short Circuit Protection
      11. 9.3.11 Thermal Shutdown
      12. 9.3.12 Input Supply Current
    4. 9.4 Device Functional Modes
      1. 9.4.1 Shutdown Mode
      2. 9.4.2 Standby Mode
      3. 9.4.3 Active Mode
        1. 9.4.3.1 CCM Mode
        2. 9.4.3.2 Auto Mode – Light-Load Operation
          1. 9.4.3.2.1 Diode Emulation
          2. 9.4.3.2.2 Frequency Reduction
        3. 9.4.3.3 FPWM Mode – Light-Load Operation
        4. 9.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 9.4.3.5 Dropout
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1  Choosing the Switching Frequency
        2. 10.2.2.2  Setting the Output Voltage
        3. 10.2.2.3  Inductor Selection
        4. 10.2.2.4  Output Capacitor Selection
        5. 10.2.2.5  Input Capacitor Selection
        6. 10.2.2.6  BOOT Capacitor
        7. 10.2.2.7  BOOT Resistor
        8. 10.2.2.8  VCC
        9. 10.2.2.9  BIAS
        10. 10.2.2.10 CFF and RFF Selection
        11. 10.2.2.11 External UVLO
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Ground and Thermal Considerations
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 サポート・リソース
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, 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

10.2.2.10 CFF and RFF Selection

A feedforward capacitor, CFF, is used to improve phase margin and transient response of circuits, which have output capacitors with low ESR. Since this capacitor can conduct noise from the output of the circuit directly to the FB node of the IC, a 1-kΩ resistor, RFF, can be placed in series with CFF. If the ESR zero of the output capacitor is below 200 kHz, no CFF must be used.

If output voltage is less than 2.5 V, CFF has little effect, so it can be omitted. If output voltage is greater than 14 V, CFF must not be used since it introduces too much gain at higher frequencies.