LT4356-3_15 Datasheet, PDF (1/24 Pages) Linear Technology – Surge Stopper with Fault Latchoff

LT4356-3
Surge Stopper with
Fault Latchoff
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}
n _{Adjustable Latchoff Fault Timer}
n _{Controls N-channel MOSFET}
n _{Shutdown Pin Withstands –60V to 100V}
n _{Fault Output Indication}
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}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Hot Swap, No R_SENSE and ThinSOT are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
DESCRIPTION
The LT^®4356-3 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 continue functioning. The LT4356-3 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 condi-
tion, a timer is started inversely proportional to MOSFET
stress. If the timer expires, the FLT pin pulls low to warn
of an impending power down. If the condition persists,
the MOSFET is turned off, until the SHDN pin pulls low
momentarily.
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. The SHDN input turns off the part, including
the auxiliary amplifier, and reduces the quiescent current
to less than 7µA.
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-3
A_OUT
GND
EN
TMR ^FLT
43563 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
LT4356-3TA01b
43563fb
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