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

3.1.2.3 ISO7637-2 Pulse 1

ISO7637-2 Pulse 1 test consists of battery disconnection where the voltage goes to zero volts and followed by -100 V. Figure 3-3 shows the typical waveform as well as the parameters for the test performed. The LM74810 should prevent reverse current as well preventing the output voltage from going negative in order to protect the rest of the circuit. Proper TVS selection performs a large role in the test to ensure the negative voltage is clamped within the 85 V operating maximum voltage across cathode to anode of the LM74810 as well as not exceed the of the 60 V MOSFETs.

  • Us: 100 V
  • Rise Time tr: 1us
  • Output Resistance: 10 Ohms
  • Pulse Width td: 2ms
  • T2: 200ms
GUID-20200710-SS0I-FJ5Z-CCMW-KR0R5FQWRJ02-low.gifFigure 3-3 ISO7637-2 Pulse 1
GUID-20200710-SS0I-7VVR-BBRP-F7PFTZPBTBC1-low.pngFigure 3-4 ISO7637-2 Pulse 1 Test

As shown in Figure 3-4, the yellow trace is the input voltage which goes negative and the TVS diode clamps the input at roughly -45 V. The blue trace is the output which decreases and the green trace is the output current to the e-load which continues to draw current until the output goes to 0 V. The pink trace is the INA302 output.