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

5.2 Power Up

To verify the startup behavior, connect the oscilloscope to the evaluation module:

  • Channel 1 - Input Voltage (Test Point Label VIN)
  • Channel 2 - A pin Voltage (Test Point Label VA)
  • Channel 3 - DGATE Voltage (Test Point Label DGATE)
  • Channel 4 - HGATE Voltage (Test Point Label HGATE)
Set the load to 200 mA, trigger to Channel 1 rising and turn ON the power supply. Start-up behavior of LM74800EVM-CS is captured in Figure 5-2.

GUID-20210211-CA0I-7KBK-LMGT-DPGVJ73SHMKD-low.pngFigure 5-2 Power Up 12 V: HGATE and Output
GUID-20210211-CA0I-JXBV-0FFT-XPDGRDQM8HN9-low.pngFigure 5-4 Power Up 12 V: Charge Pump VCAP
GUID-20210211-CA0I-TQ00-5T4C-KVQSSHPZFKSF-low.pngFigure 5-3 Power Up 12 V: DGATE and A
GUID-20210211-CA0I-NZXC-CSLB-SC6S5B72FB6H-low.pngFigure 5-5 Power Up 12 V: DGATE and HGATE