ZHCSNL2A February 2022 – May 2022 LM74502-Q1 , LM74502H-Q1
PRODUCTION DATA
Many automotive applications are designed to comply with unsuppressed load dump transients specified by ISO16750-2 Pulse 5A. LM74502, LM74502H can be configured as input surge stopper to provide overvoltage along with input reverse supply protection and protect the downstream loads in case of unsuppressed load dump event.
As shown in Figure 10-11, MOSFET Q1 is used to turn off or clamp output voltage to acceptable safe level and protect the MOSFET Q2 and LM74502 from input transient. Note that only the VS pin is exposed to input transient through a resistor, R1. A 60-V rated Zener diode is used to clamp and protect the VS pin within recommended operating condition. Th 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.