SNOSDB8A June   2021  – December 2021 LM74701-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 Gate Driver
      4. 8.3.4 Enable
      5. 8.3.5 Battery Voltage Monitoring (SW)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Conduction Mode
        1. 8.4.2.1 Regulated Conduction Mode
        2. 8.4.2.2 Full Conduction Mode
        3. 8.4.2.3 VDS Clamp Mode
      3. 8.4.3 Reverse Current Protection Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    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 Charge Pump VCAP (CVCAP) and Input Capacitance (CIN)
        4. 9.2.2.4 Output Capacitance (COUT)
      3. 9.2.3 Application Curves
    3. 9.3 What to Do and What Not to Do
    4. 9.4 OR-ing Application Configuration
  10. 10Power Supply Recommendations
  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

9.2.2.4 Output Capacitance (COUT)

LM74701-Q1 CATHODE pin is capable of handling negative voltage. However, if loads connected to LM74701-Q1 output are not capable of handling negative voltage, then sufficient output capacitor is required to ensure output does not swing negative during ISO7637-2 pulse 1 operation.

The required output capacitor during ISO7637-2 pulse 1 to ensure output does not swing negative can be calculated using Equation 5.

Equation 5. COUT = (ILOAD + IISO_AVG) × 1 ms / ΔVOUT

Where ΔVOUT is difference between output voltage at the start and the end of ISO7637-2 pulse 1.