JAJU793 October   2020

 

  1.   概要
  2.   リソース
  3.   アプリケーション
  4.   特長
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Ideal Diode Design Overview
      2. 2.2.2 Current Sensing Amplifier Design Overview
      3. 2.2.3 OR Gate Design Overview
      4. 2.2.4 MOSFET Selection
        1. 2.2.4.1 Blocking MOSFET
        2. 2.2.4.2 Hot-Swap MOSFET
      5. 2.2.5 TVS Input Diode Selection
      6. 2.2.6 Inrush Current
    3. 2.3 Highlighted Products
      1. 2.3.1 LM74810-Q1
      2. 2.3.2 INA302-Q1
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1 Getting Started
      2. 3.1.2 Testing and Results
        1. 3.1.2.1 Over-Voltage Protection Cut-Off Mode
        2. 3.1.2.2 Over-Voltage Protection Clamping-Mode
        3. 3.1.2.3 ISO7637-2 Pulse 1
        4. 3.1.2.4 Overcurrent Protection
        5. 3.1.2.5 Load Dump
        6. 3.1.2.6 Cold Crank, Warm Start, and Cold Start
          1. 3.1.2.6.1 Cold Crank
          2. 3.1.2.6.2 Warm Start
          3. 3.1.2.6.3 Cold Start
        7. 3.1.2.7 Standby Current
        8. 3.1.2.8 Currency Sense Accuracy
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 サポート・リソース
    4. 4.4 Trademarks

2.2.1 Ideal Diode Design Overview

LM74810-Q1 is an ideal diode controller that drives and controls external back to back N-Channel MOSFETs. The first MOSFET to replace a Schottky diode and the second MOSFET allows load disconnect switch control. LM74810-Q1 has a wide input supply 3 V to 65 V, ideal for protection and control of 12 V automotive battery systems. Through controlling the MOSFETs, LM74810-Q1 provides reverse input protection, Reverse current blocking, in-rush current control, and adjustable over voltage protection.

TIDA-020040 controls two sets of MOSFETs in parallel to aid in decreasing power dissipation from the MOSFETs Rdson at high currents.

Adjustable over voltage protection is controlled through a resistor divider and connection to the OV pin of LM74810-Q1 which goes to an internal comparator with a set 1.23 V reference. When the voltage applied to OV is higher than the 1.23 V reference, overvoltage is triggered.

The design allows shorting J1 connector for over voltage clamping or shorting J3 connector for over voltage cut-off. For both connections, the resistor divider is the same to allow over voltage to trigger at 18.2 V.

GUID-20200710-SS0I-NN8B-NQQF-7RT3XPGJTZ5H-low.gif Figure 2-4 Over Voltage Resistor Divider Schematic