SNOSDE5A December   2021  – May 2022 LM74502 , LM74502H

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 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. 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

MOSFET Selection

The important MOSFET electrical parameters are the maximum continuous drain current ID, the maximum drain-to-source voltage VDS(MAX), the maximum gate-to-source voltage VGS(MAX) and the drain-to-source On resistance RDSON.

The maximum continuous drain current, ID, rating must exceed the maximum continuous load current. The maximum drain-to-source voltage, VDS(MAX), must be high enough to withstand the highest differential voltage seen in the application. This requirement would include any anticipated fault conditions. The maximum VGS LM74502 can drive is 13.9 V, so a MOSFET with 15-V minimum VGS rating must be selected. If a MOSFET with VGS rating < 15 V is selected, a zener diode can be used between GATE to SRC pin to clamp VGS to safe level.

To reduce the MOSFET conduction losses, lowest possible RDS(ON) is preferred. Selecting a MOSFET with RDS(ON) that gives VDS drop 20 mV to 50 mV provides good trade off in terms of power dissipation and cost.

Thermal resistance of the MOSFET must be considered against the expected maximum power dissipation in the MOSFET to ensure that the junction temperature (TJ) is well controlled.