SLVSFH8B September   2021  – March 2022 LM74720-Q1

PRODUCTION DATA  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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. Parameter Measurement Information
  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)
      2. 8.3.2 Overvoltage Protection and Battery Voltage Sensing (VSNS, SW, OV)
      3. 8.3.3 Boost Regulator
    4. 8.4 Device Functional Mode (Shutdown Mode)
  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
      2. 9.2.2 Automotive Reverse Battery Protection
        1. 9.2.2.1 Input Transient Protection: ISO 7637-2 Pulse 1
        2. 9.2.2.2 AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06
        3. 9.2.2.3 Input Micro-Short Protection: LV124 E-10
      3. 9.2.3 Detailed Design Procedure
        1. 9.2.3.1 Design Considerations
        2. 9.2.3.2 Boost Converter Components (C2, C3, L1)
        3. 9.2.3.3 Input and Output Capacitance
        4. 9.2.3.4 Hold-Up Capacitance
        5. 9.2.3.5 Overvoltage Protection and Battery Monitor
        6. 9.2.3.6 MOSFET Selection: Blocking MOSFET Q1
        7. 9.2.3.7 MOSFET Selection: Load Disconnect MOSFET Q2
        8. 9.2.3.8 TVS Selection
      4. 9.2.4 Application Curves
    3. 9.3 Do's and Don'ts
  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 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Layout Guidelines

  • For the ideal diode stage, connect A, GATE and C pins of LM74720-Q1 close to the MOSFET's SOURCE, GATE and DRAIN pins.
  • The high current path of for this solution is through the MOSFET; therefore, it is important to use thick and short traces for source and drain of the MOSFET to minimize resistive losses.
  • The GATE pin of the LM74720-Q1 must be connected to the MOSFET GATE with short trace.
  • Boost converter switching currents flow into LX, CAP, GND pins and C3 (across DRAIN of the FET to GND). The loops formed by capacitor across CAP pin and DRAIN of the FET and C3 to GND must be minimized by placing these capacitors as close as possible. Keep the GND side of the C3 capacitor close to GND pin of LM74720-Q1.
  • Place transient suppression components like input TVS and output Schottky close to LM74720-Q1.