ZHCSNL2A February   2022  – May 2022 LM74502-Q1 , LM74502H-Q1

PRODUCTION DATA  

  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. Parameter Measurement Information
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Input Voltage (VS)
      2. 9.3.2 Charge Pump (VCAP)
      3. 9.3.3 Gate Driver (GATE an SRC)
        1. 9.3.3.1 Inrush Current Control
      4. 9.3.4 Enable and Undervoltage Lockout (EN/UVLO)
      5. 9.3.5 Overvoltage Protection (OV)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Shutdown Mode
      2. 9.4.2 Conduction Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Design Considerations
        2. 10.2.2.2 MOSFET Selection
        3. 10.2.2.3 Overvoltage Protection
        4. 10.2.2.4 Charge Pump VCAP, Input and Output Capacitance
      3. 10.2.3 Selection of TVS Diodes for 12-V Battery Protection Applications
      4. 10.2.4 Selection of TVS Diodes and MOSFET for 24-V Battery Protection Applications
      5. 10.2.5 Application Curves
    3. 10.3 Surge Stopper Using LM74502-Q1, LM74502H-Q1
      1. 10.3.1 VS Capacitance, Resistor R1 and Zener Clamp (DZ)
      2. 10.3.2 Overvoltage Protection
      3. 10.3.3 MOSFET Selection
    4. 10.4 Fast Turn-On and Turn-Off High Side Switch Driver Using LM74502H-Q1
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 接收文档更新通知
    2. 13.2 支持资源
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 术语表
  14. 14Mechanical, Packaging, and 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 source current through body diode, 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 includes any anticipated fault conditions. TI recommends to use MOSFETs with voltage rating up to 60-V maximum with the LM74502-Q1 because SOURCE pin maximum voltage rating is 65 V. The maximum VGS LM74502-Q1 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 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 at full load 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.