ZHCSO25A December   2021  – May 2022 LM74502 , LM74502H

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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 接收文档更新通知
    2. 12.2 支持资源
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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8.3.4 Enable (EN/UVLO)

The LM74502 has an enable pin, EN/UVLO. The enable pin allows for the gate driver to be either enabled or disabled by an external signal. If the EN/UVLO pin voltage is greater than the rising threshold, the gate driver and charge pump operates as described in the Gate Driver (GATE, SRC) and Charge Pump (VCAP) sections. If the enable pin voltage is less than the input low threshold, the charge pump and gate driver are disabled placing the LM74502 in shutdown mode. The EN/UVLO pin can withstand a voltage as large as 65 V and as low as –65 V. This feature allows for the EN/UVLO pin to be connected directly to the VS pin if enable functionality is not needed. In conditions where EN/UVLO is left floating, the internal sink current of 3 uA pulls EN/UVLO pin low and disables the device.

An external resistor divider connected from input to EN/UVLO to ground can be used to implement the input Undervoltage Lockout (UVLO) functionality in the system. When EN/UVLO pin voltage is lower than UVLO comparator falling threshold (VEN/UVLOR) but higher than enable falling threshold (VENF), the device disables gate drive voltage, however, charge pump is kept on. This action ensures quick recovery of gate drive when UVLO condition is removed. If UVLO functionality is not required, connect EN/UVLO pin to VS.