TIDUEX5 October   2020

 

  1.   Description
  2.   Resources
  3.   Applications
  4.   Features
  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 Support Resources
    4. 4.4 Trademarks
3.1.2.6.1 Cold Crank

Cold crank testing is performed to ensure the design prevents reverse current during conditions where the input is lower than the output.

GUID-20200710-SS0I-5QLP-LR8V-9N4MPFNCMT6K-low.png Figure 3-11 Cold Crank Waveform
GUID-20200710-SS0I-LBKM-BFML-JTQLDVLR7ZTV-low.png Figure 3-12 Cold Crank Reverse Current Testing

As shown in Figure 3-11, the input voltage drops to be lower than the output voltage for a period of time before eventually moving back to normal voltage levels. In these cold crank events, LM74810 provides reverse current blocking through the use of the DGATE driven MOSFETs. As shown in Figure 3-12, the green trace which is the DGATE voltage, turns off when the input voltage drops to prevent reverse current to flow back to the battery. For the testing shown in Figure 3-12, the current load is set to a 4A load.