1.2 Applications
• Automotive reverse battery protection
• ADAS domain controller
• Camera ECU
• Head unit
• USB HUBs
• Power path protection, Power Mux and ORing
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.
2.1 Input Power and Load (J1/J3 and J2/J4):
Input power is applied at the terminals J1 and J3. Terminals J2 and J4 provide output connection to load.
2.2 Enable Control (J5):
Enable control is usually used by external MCU or controller to turn off LM7480x-Q1 and cut off the power path.
External input is recommended to be connected to jumper J5 pin 2. Otherwise setting 1-2 on J5 enables the
controller and 2-3 disables the controller. It is recommended to connect EN to external MCU for uninterrupted
performance during negative transient tests.
2.3 Over Voltage Protection (J6):
Over voltage protection is configured through jumper J6. Setting 2-3 on J6 configures OVP protection to the
input side. OVP rising threshold is set to 38.4 V with 2-3 setting on J6 and falling is set to 35.2 V. Setting 1-2 on
J6 configures OV clamp operation. This provides output voltage to clamp (hysteretic ON/OFF output).
2.4 Two Back-Back Connected MOSFETs (Q1/Q3 and Q2):
Q1 and Q2 are 200-V and 60-V rated N-Channel MOSFETs respectively which are capable of supporting 2-A
load current for automotive applications. Since the MOSFETs are connected back to back in common-source
topology, they can support 200-V unsuppressed load dump protection, reverse battery protection, reverse-
current blocking and can provide power path cut-off when disabled or during over voltage conditions. Option Q3
provids for extending current to 5 A and can be used to validate other MOSFETs.
2.5 Output Slew Rate Control (R2 and C4):
R2 and C4 provide output slew rate control and can be changed to achieve different output slew rate.
2.6 Output Schottky Diode (D3) and LED Indication:
Schottky Diode D3 is not populated on EVM by default and it is recommended where output voltage can have
negative transients that can exceed absolute maximum ratings of LM7480x-Q1.
D5 provides an indication on the status of the output voltage.
2.7 TVS Selection for 200-V Unsuppressed Load Dump Protection:
Two TVS diodes D1 and D2 are required at the input. The breakdown voltage of two TVS in the positive side is
higher than the maximum system voltage, 200 V. On the negative side, diode D3 is used to clamp ISO 7637-2
pulse 1. SMBJ150A for D2 and SMBJ33CA for D1 are recommended.
2.8 Test Points:
Test point labeled DGATE (TP4) is used for monitoring gate voltage of Q2 and HGATE (TP3) is used for gate
voltage of Q1. Test Point labelled VIN (TP1) measures input voltage, VOUT (TP2) measure output voltage. Test
Point labelled VA (TP6) measures the source voltage of Q1 and Q2 MOSFETs which is also connected to the A
Introduction
2
LM7480-Q1 Evaluation Module for Unsuppressed Load Dump Protection:
LM74800EVM-CS
SLVUBU4 – MARCH 2021
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