JAJSR90 September   2023 LMQ644A2-Q1

PRODMIX  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
    1. 6.1 Wettable Flanks
  8. 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 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input Voltage Range (VIN)
      2. 8.3.2  Enable EN Pin and Use as VIN UVLO
      3. 8.3.3  Output Voltage Selection and Soft Start
      4. 8.3.4  SYNC Allows Clock Synchronization and Mode Selection
      5. 8.3.5  Clock Locking
      6. 8.3.6  Adjustable Switching Frequency
      7. 8.3.7  Power-Good Output Voltage Monitoring
      8. 8.3.8  Internal LDO, VCC UVLO, and BIAS Input
      9. 8.3.9  Bootstrap Voltage and VCBOOT-UVLO (CB1 and CB2 Pin)
      10. 8.3.10 CONFIG Device Configuration Pin
      11. 8.3.11 Spread Spectrum
      12. 8.3.12 Soft Start and Recovery From Dropout
      13. 8.3.13 Overcurrent and Short-Circuit Protection
      14. 8.3.14 Hiccup
      15. 8.3.15 Thermal Shutdown
    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 Peak Current Mode Operation
        2. 8.4.3.2 Auto Mode Operation
          1. 8.4.3.2.1 Diode Emulation
        3. 8.4.3.3 FPWM Mode Operation
        4. 8.4.3.4 Minimum On-time (High Input Voltage) Operation
        5. 8.4.3.5 Dropout
        6. 8.4.3.6 Recovery from Dropout
        7. 8.4.3.7 Other Fault Modes
  10. 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  VCC
        8. 9.2.2.8  CFF and RFF Selection
        9. 9.2.2.9  SYNCHRONIZATION AND MODE
        10. 9.2.2.10 External UVLO
        11. 9.2.2.11 Typical Thermal Performance
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Ground and Thermal Considerations
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 サード・パーティ製品に関する免責事項
    2. 10.2 ドキュメントの更新通知を受け取る方法
    3. 10.3 サポート・リソース
    4. 10.4 Trademarks
    5. 10.5 用語集
    6. 10.6 静電気放電に関する注意事項
  12. 11Mechanical, 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

8.3.1 Input Voltage Range (VIN)

The LMQ644xx can start up from 3.5 V to 36 V, after start-up the input voltage range can extend down to 3 V. The device is intended for step-down conversions from 12-V automotive and 24-V industrial supply rails. The application circuit shows all the necessary components to implement an LMQ644xx based wide-VIN dual-output step-down regulator using a single supply. The LMQ644xx uses an internal LDO subregulator to provide a VCC bias rail for the gate drive and control circuits.

GUID-20230825-SS0I-SPJK-GRHS-4TMTG61QNQB5-low.svg Figure 8-1 Dual-Output Regulator Schematic Diagram With Input Voltage Operating Range of 6 V to 36 V

In high input voltage applications, take extra care to make sure the VIN and SW pins do not exceed their absolute maximum voltage rating of 42 V during line or load transient events. Voltage excursions that exceed the maximum ratings can damage the IC. Proceed carefully during PCB board layout and use high-quality input bypass capacitors to minimize voltage overshoot and ringing.