JAJSLH6A February   2022  – May 2022 LM74502-Q1 , LM74502H-Q1

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 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. 8 Parameter Measurement Information
  9. 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 Receiving Notification of Documentation Updates
    2. 13.2 サポート・リソース
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

10.2.4 Selection of TVS Diodes and MOSFET for 24-V Battery Protection Applications

Typical 24-V battery protection application circuit shown in Figure 10-2 uses two uni-directional TVS diodes to protect from positive and negative transient voltages.

Figure 10-2 Typical 24-V Battery Protection with Two Uni-Directional TVS

The breakdown voltage of the TVS+ must be higher than 48-V jump start voltage, less than the absolute maximum ratings of source and enable pin of LM74502-Q1 (65 V) and must withstand 65-V suppressed load dump. The breakdown voltage of TVS– must be lower than maximum reverse battery voltage –32 V, so that the TVS– is not damaged due to long time exposure to reverse connected battery.

During ISO 7637-2 pulse 1, the input voltage goes up to –600 V with a generator impedance of 50 Ω. Single bi-directional TVS cannot be used for 24-V battery protection because breakdown voltage for TVS+ ≥ 48 V, maximum negative clamping voltage is ≤ –65 V . Two uni-directional TVS connected back-to-back must be used at the input. For positive side TVS+, TI recommends SMBJ58A with the breakdown voltage of 64.4 V (minimum), 67.8 (typical). For the negative side TVS–, TI recommends SMBJ26A with breakdown voltage close to 32 V (to withstand maximum reverse battery voltage –32 V) and maximum clamping voltage of 42 V.

For 24-V battery protection, TI recommends a 75-V rated MOSFET to be used along with SMBJ26A and SMBJ58A connected back-to-back at the input.