LT4363_15 Datasheet, PDF (1/24 Pages) Linear Technology – High Voltage Surge Stopper with Current Limit

LT4363
High Voltage Surge
Stopper with Current Limit
Features
n _{Withstands Surges Over 100V with VCC Clamp}
n _{Wide Operating Voltage Range: 4V to 80V}
n _{Adjustable Output Clamp Voltage}
n _{Fast Overcurrent Limit: Less Than 5µs}
n _{Reverse Input Protection to –60V}
n _{Adjustable UV/OV Comparator Thresholds}
n _{Low 7µA Shutdown Current}
n _{Shutdown Pin Withstands –60V to 100V}
n _{Adjustable Fault Timer}
n _{Controls N-Channel MOSFET}
n _{Less Than 1% Retry Duty Cycle During Faults,}
LT4363-2
n _{Available in 12-Pin (4mm × 3mm) DFN, 12-Pin}
MSOP and 16-Pin SO Packages
Applications
n _{Automotive/Avionic/Industrial 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
No R_SENSE, ThinSOT and Hot Swap are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Description
The LT^®4363 surge stopper protects loads from high voltage
transients. It regulates the output during an overvoltage
event, such as load dump in vehicles, by controlling the
gate of an external N-channel MOSFET. The output is limited
to a safe value allowing the loads to continue functioning.
The LT4363 also monitors the voltage drop between the
SNS and OUT pins to protect against overcurrent faults.
An internal amplifier limits the voltage across the current
sense resistor to 50mV. In either fault condition, a timer is
started inversely proportional to MOSFET stress. Before 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. The LT4363-1 remains off until reset whereas
the LT4363-2 restarts after a cool down period.
Two precision comparators can monitor the input supply
for overvoltage (OV) and undervoltage (UV) conditions.
When the potential is below the UV threshold, the external
MOSFET is kept off. If the input supply voltage is above the
OV threshold, the MOSFET is not allowed to turn back on.
Back-to-back MOSFETs 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 during shutdown.
Typical Application
4A, 12V Overvoltage Output Regulator with 150V Surge Protection
V_IN
12V
0.1µF
127k
SMAJ58A
49.9k
FDB33N25 10mΩ
1k
10Ω
V_CC GATE SNS
SHDN
UV LT4363-2
OUT
FB
ENOUT
OV _{GND TMR} FLT
4363 TA01
0.1µF
22µF
57.6k
OUTPUT
CLAMP
AT 16V
4.99k
FAULT
V_CC
DC/DC
CONVERTER
SHDN _GND
V_IN
20V/DIV
Overvoltage Protector Regulates
Output at 27V During Transient
80V INPUT SURGE
C_TMR = 6.8µF
I_LOAD = 500mA
12V
V_OUT
20V/DIV
12V
27V ADJUSTABLE CLAMP
100ms/DIV
4363 TA01b
For more information www.linear.com/LT4363
4363fb
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