JAJSJ94B September   2021  – August 2022 LM74722-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 Pin Configuration and Functions
  6. 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 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Dual Gate Control (GATE, PD)
        1. 8.3.1.1 Reverse Battery Protection (A, C, GATE)
        2. 8.3.1.2 Load Disconnect Switch Control (PD)
        3. 8.3.1.3 Overvoltage Protection and Battery Voltage Sensing (VSNS, SW, OV)
      2. 8.3.2 Boost Regulator
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical 12-V Reverse Battery Protection Application
      1. 9.2.1 Design Requirements for 12-V Battery Protection
        1. 9.2.1.1 Automotive Reverse Battery Protection
          1. 9.2.1.1.1 Input Transient Protection: ISO 7637-2 Pulse 1
          2. 9.2.1.1.2 AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06
          3. 9.2.1.1.3 Input Micro-Short Protection: LV124 E-10
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Design Considerations
        2. 9.2.2.2 Boost Converter Components (C2, C3, L1)
        3. 9.2.2.3 Input and Output Capacitance
        4. 9.2.2.4 Hold-Up Capacitance
        5. 9.2.2.5 Overvoltage Protection and Battery Monitor
        6. 9.2.2.6 MOSFET Selection: Blocking MOSFET Q1
        7. 9.2.2.7 MOSFET Selection: Load Disconnect MOSFET Q2
        8. 9.2.2.8 TVS Selection
      3. 9.2.3 Application Curves
    3. 9.3 What to Do and What Not to Do
  10. 10Power Supply Recommendations
    1. 10.1 Transient Protection
    2. 10.2 TVS Selection for 12-V Battery Systems
    3. 10.3 TVS Selection for 24-V Battery Systems
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 サポート・リソース
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 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
9.2.1.1.2 AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06

Alternators are used to power the automotive electrical system and charge the battery during normal run time of the vehicle. Rectified alternator output contains residual AC ripple voltage superimposed on the DC battery voltage due to various reasons. These reasons include engine speed variation, regulator duty cycle with field switching ON and OFF, and electrical load variations. On a 12-V battery supply, alternator output voltage is regulated by a voltage regulator between 14.5 V to 12.5 V by controlling the field current of alternator rotor. All electronic modules are tested for proper operation with superimposed AC ripple on the DC battery voltage. AC super imposed test specified in ISO 16750-2 and LV124 E-06 requires AC ripple of 2-V peak-peak on a 13.5-V DC battery voltage, swept from 15 Hz to 30 kHz. LM74722-Q1 rectifies the AC superimposed voltage by turning the MOSFET Q1 OFF quickly to cut off reverse current and turning the MOSFET Q1 ON quickly during forward conduction. Figure 9-3 shows active rectification of 6-V peak-peak 100-kHz AC input by LM74722-Q1. Fast turn-off and quick turn-on of the MOSFET reduces power dissipation in the MOSFET Q1, and active rectification reduces power dissipation in the output hold-up capacitor ESR by half. Figure 9-4 shows active rectification of 2-V peak-peak 200-kHz AC input.

GUID-20210923-SS0I-23J6-L39P-27MFM6XXMSNR-low.gifFigure 9-3 AC Super Imposed Test - 6-V Peak-Peak 100 kHz
GUID-20210923-SS0I-WHTJ-D6ZS-KQBVFPZ9FZZ6-low.gifFigure 9-4 AC Super Imposed Test - 2-V Peak-Peak 200 kHz