SNOSD87A July   2021  – February 2022 LM74501-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 Input Voltage
      2. 8.3.2 Charge Pump
      3. 8.3.3 Enable
      4. 8.3.4 Gate Driver
      5. 8.3.5 SW (Battery Voltage Monitoring)
      6. 8.3.6 Gate Discharge Timer
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Full Conduction Mode
      3. 8.4.3 VDS Clamp
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Reverse Battery Protection
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Design Considerations
        2. 9.2.2.2 MOSFET Selection
        3. 9.2.2.3 Gate Discharge Timer Capacitor Selection (CT)
        4. 9.2.2.4 Charge Pump VCAP, Input and Output Capacitance
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 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

8.3.5 SW (Battery Voltage Monitoring)

The LM74501-Q1 has an SW pin to enable battery voltage monitoring in automotive systems. When the device is enabled, an internal switch connects the SW pin to SOURCE. This connection enables monitoring battery voltage using an external resistor divider connected from SW pin to GND. When LM74501-Q1 is put in shutdown mode by pulling down the EN pin to ground, an internal switch between SW and SOURCE pin is disconnected. This disconnection ensures there is no quiescent current drawn by the resistor ladder when system is put into low power shutdown mode. When not used, the SW pin can be left floating.

GUID-20210621-CA0I-MNKN-1QQL-PHZPZJQNF1PG-low.gifFigure 8-2 LM74501-Q1 SW Functionality