LT4356-2_15 Datasheet, PDF (1/26 Pages) Linear Technology – Surge Stopper

LT4356-1/LT4356-2
Surge Stopper
FEATURES
n _{Stops High Voltage Surges}
n _{Adjustable Output Clamp Voltage}
n _{Overcurrent Protection}
n _{Wide Operation Range: 4V to 80V}
n _{Reverse Input Protection to –60V}
n _{Low 7μA Shutdown Current, LT4356-1}
n _{Adjustable Fault Timer}
n _{Controls N-channel MOSFET}
n _{Shutdown Pin Withstands –60V to 100V}
n _{Fault Output Indication}
n _{Guaranteed Operation to 125°C}
n _{Auxiliary Amplifier for Level Detection Comparator or}
Linear Regulator Controller
n _{Available in (4mm × 3mm) 12-Pin DFN,}
10-Pin MSOP or 16-Pin SO Packages
APPLICATIONS
n _{Automotive/Avionic Surge Protection}
n _{Hot Swap/Live Insertion}
n _{High Side Switch for Battery Powered Systems}
n _{Intrinsic Safety Applications}
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Technology Corporation. All other trademarks are the property of their respective owners.
DESCRIPTION
The LT^®4356 surge stopper protects loads from high voltage
transients. It regulates the output during an overvoltage
event, such as load dump in automobiles, by controlling
the gate of an external N-channel MOSFET. The output is
limited to a safe value thereby allowing the loads to con-
tinue functioning. The LT4356 also monitors the voltage
drop between the V_CC and SNS pins to protect against
overcurrent faults. An internal amplifier limits the current
sense voltage to 50mV. In either fault condition, a timer
is started inversely proportional to MOSFET stress. If the
timer expires, the FLT pin pulls low to warn of an impend-
ing power down. If the condition persists, the MOSFET is
turned off. After a cool down period, the GATE pin pulls
up turning on the MOSFET again.
The auxiliary amplifier may be used as a voltage detection
comparator or as a linear regulator controller driving an
external PNP pass transistor.
Back-to-back FETs can be used in lieu of a Schottky diode
for reverse input protection, reducing voltage drop and
power loss. A shutdown pin reduces the quiescent current
to less than 7μA for the LT4356-1 during shutdown. The
LT4356-2 differs from the LT4356-1 during shutdown by
reducing the quiescent current to 60μA and keeping alive
the auxiliary amplifier for uses such as an undervoltage
lockout or always-on regulator.
TYPICAL APPLICATION
4A, 12V Overvoltage Output Regulator
V_IN
10mΩ IRLR2908
V_OUT
12V
383k
100k
UNDERVOLTAGE
10Ω
V_CC
SHDN
IN⁺
SNS GATE OUT
FB
LT4356DE
A_OUT
GND
EN
TMR ^FLT
4356 TA01
0.1μF
102k
4.99k
V_CC
DC-DC
CONVERTER
SHDN _GND
FAULT
Overvoltage Protector Regulates Output at
27V During Transient
80V INPUT SURGE
C_TMR = 6.8μF
I_LOAD = 500mA
V_IN
20V/DIV
12V
V_OUT
20V/DIV
12V
27V ADJUSTABLE CLAMP
100ms/DIV
4356 TA01b
4356fa
1