SLVUBU4 March   2021

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Features
    2. 1.2 Applications
  3. 2Description
    1. 2.1 Input Power and Load (J1/J3 and J2/J4):
    2. 2.2 Enable Control (J5):
    3. 2.3 Over Voltage Protection (J6):
    4. 2.4 Two Back-Back Connected MOSFETs (Q1/Q3 and Q2):
    5. 2.5 Output Slew Rate Control (R2 and C4):
    6. 2.6 Output Schottky Diode (D3) and LED Indication:
    7. 2.7 TVS Selection for 200-V Unsuppressed Load Dump Protection:
    8. 2.8 Test Points:
  4. 3Schematic
  5. 4Test Equipment Requirements
    1. 4.1 Power Supplies
    2. 4.2 Meters
    3. 4.3 Oscilloscope
    4. 4.4 Loads
  6. 5Test Setup and Results
    1. 5.1 Initial Setup
    2. 5.2 Power Up
    3. 5.3 200-V Unsuppressed Load Dump Protection
    4. 5.4 ISO 7637-2 Pulse 1 –600 V 50 Ω
  7. 6Board Layout and Bill of Materials
    1. 6.1 Board Layout
    2. 6.2 Bill of Materials
  8.   Revision History

2 Description

The LM74800EVM-CS is configured by default for evaluating 24-V battery, 6 V during cold crank 200-V unsuppressed load dump protection with reverse battery protection. Note that during 200-V unsuppressed load dump protection, only the VS pin will be exposed to 200 V through a 10-kΩ resistor. A 60-V rated zener diode is used to clamp and protect the VS pin. The rest of the circuit is not exposed to higher voltage as the MOSFET Q1 can either be turned off completely or output voltage clamped to safe level.