SNOSDE5A December   2021  – May 2022 LM74502 , LM74502H

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 (VCAP)
      3. 8.3.3 Gate Driver (GATE, SRC)
        1. 8.3.3.1 Inrush Current Control
      4. 8.3.4 Enable (EN/UVLO)
      5. 8.3.5 Overvoltage Protection (OV)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Conduction 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 Overvoltage Protection
        4. 9.2.2.4 Charge Pump VCAP, Input and Output Capacitance
      3. 9.2.3 Application Curves
    3. 9.3 Input Surge Stopper Using LM74502, LM74502H
      1. 9.3.1 VS Capacitance, Resistor R1 and Zener Clamp (DZ)
      2. 9.3.2 Overvoltage Protection
      3. 9.3.3 MOSFET Selection
    4. 9.4 Fast Turn-On and Turn-Off High Side Switch Driver Using LM74502H
  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

Package Options

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

9.2.2.3 Overvoltage Protection

Resistors R1 and R2 connected in series is used to program the overvoltage threshold. Connecting R1 to VIN provides overvoltage cutoff and switching the connection to VOUT provides overvoltage clamp response. The resistor values required for setting the overvoltage threshold VOV to 37 V are calculated by solving Equation 3

Equation 3.

For minimizing the input current drawn from the supply through resistors R1 and R2, it is recommended to use higher value of resistance. Using high value resistors adds error in the calculations because the current through the resistors at higher value becomes comparable to the leakage current into the OV pin. Select (R1 + R2) such that current through resistors is around 100 times higher than the leakage through OV pin. Based on the device electrical characteristics, VOVR is 1.25 V , Select (R1) = 100 kΩ and R2 = 3.5 kΩ as a standard resistor value to set overvoltage cutoff of 37 V.