SNOSDC2B September   2021  – July 2022 LM74721-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 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. 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

Overview

The LM74721-Q1 ideal diode controller drives and controls external N-Channel MOSFET to emulate an ideal diode rectifier. The wide input supply of 3 V to 65 V allows protection and control of 12-V automotive battery powered ECUs. IQ during operation (EN = High) is < 35 µA and < 3.3 µA during shutdown mode (EN = Low). The device can withstand and protect the loads from negative supply voltages down to –33-V DC. Integrated VDS clamp feature enables input TVS less system designs for automotive ISO7637 pulse suppression. An integrated ideal diode controller (GATE) drives the first MOSFET to replace a Schottky diode for reverse input protection and output voltage holdup. A strong 30-mA boost regulator and short turn ON and turn OFF delay times of comparator ensures fast transient response, ensuring robust and efficient MOSFET switching performance during automotive testing, such as ISO16750 or LV124, where an ECU is subjected to input short interruptions and AC superimpose input signals up to 100-kHz frequency.

The LM74721-Q1 controls the GATE of the MOSFET to regulate the forward voltage drop at 17 mV. The linear regulation scheme in these devices enables graceful control of the GATE voltage and turns off of the MOSFET during a reverse current event and ensures zero DC reverse current flow.

Low quiescent current (< 35 µA) in operation enables always ON system designs. With a second MOSFET in the power path, the device allows load disconnect control using EN pin. Quiescent current reduces to < 3.3 μA with EN low.