SNOSDC2B September   2021  – July 2022 LM74721-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Reverse Battery Protection (A, C, GATE)
        1. 8.3.1.1 Input TVS Less Operation: VDS Clamp
      2. 8.3.2 Load Disconnect Switch Control (PD)
      3. 8.3.3 Overvoltage Protection and Battery Voltage Sensing (VSNS, SW, OV)
      4. 8.3.4 Boost Regulator
    4. 8.4 Shutdown Mode
  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
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Boost Converter Components (C2, C3, L1)
        2. 9.2.2.2 Input and Output Capacitance
        3. 9.2.2.3 Hold-Up Capacitance
        4. 9.2.2.4 MOSFET Selection: Q1
      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
  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 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.1 Design Requirements for 12-V Battery Protection

Table 9-1 lists the system design requirements.

Table 9-1 Design Parameters – 12-V Reverse Battery Protection and Overvoltage Protection
DESIGN PARAMETEREXAMPLE VALUE
Operating input voltage range12-V battery, 12-V nominal with 3.2-V cold crank and 35-V load dump
Output power50 W
Output current range4-A nominal, 5-A maximum
Input capacitance0.1-µF minimum
Output capacitance220 µF × 3
AC super imposed test2-V peak-peak, 30 kHz

(maximum)

Automotive transient immunity complianceISO 7637-2 with pulse 1 maximum level of –100-V peak level and 10-Ω generator impedance, ISO 16750-2 and LV124