JAJSQL9C may   2018  – august 2023 LV3842

ADVANCE INFORMATION  

  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
  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 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 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 Fixed Frequency Peak Current Mode Control
      2. 8.3.2 Adjustable Output Voltage
      3. 8.3.3 Enable
      4. 8.3.4 Minimum ON-Time, Minimum OFF-Time and Frequency Foldback
      5. 8.3.5 Bootstrap Voltage
      6. 8.3.6 Overcurrent and Short-Circuit Protection
      7. 8.3.7 Soft Start
      8. 8.3.8 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
      3. 8.4.3 CCM Mode
      4. 8.4.4 Light-Load Operation (PFM Version)
      5. 8.4.5 Light-Load Operation (FPWM Version)
  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 Output Voltage Set-Point
        2. 9.2.2.2 Inductor Selection
        3. 9.2.2.3 Output Capacitor Selection
        4. 9.2.2.4 Input Capacitor Selection
        5. 9.2.2.5 Bootstrap Capacitor
        6. 9.2.2.6 Undervoltage Lockout Set-Point
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Compact Layout for EMI Reduction
      3. 9.4.3 Feedback Resistors
      4. 9.4.4 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    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 静電気放電に関する注意事項
    6. 10.6 用語集
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel 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

8.4.4 Light-Load Operation (PFM Version)

For PFM version, when the load current is lower than half of the peak-to-peak inductor current in CCM, the LV3842 operates in Discontinuous Conduction Mode (DCM), also known as Diode Emulation Mode (DEM). In DCM operation, the LS switch is turned off when the inductor current drops to ILS_ZC (20 mA typical) to improve efficiency. Both switching losses and conduction losses are reduced in DCM, compared to forced PWM operation at light load.

At even lighter current load, Pulse Frequency Modulation (PFM) mode is activated to maintain high efficiency operation. When either the minimum HS switch ON time tON_MIN or the minimum peak inductor current IPEAK_MIN (150mA typical) is reached, the switching frequency decreases to maintain regulation. In PFM mode, switching frequency is decreased by the control loop to maintain output voltage regulation when load current reduces. Switching loss is further reduced in PFM operation due to less frequent switching actions.