LT4363
1
4363fb
For more information
100ms/DIV
4363 TA01b
V
IN
20V/DIV
V
OUT
20V/DIV
80V INPUT SURGE
C
TMR
= 6.8µF
I
LOAD
= 500mA
27V ADJUSTABLE CLAMP
12V
12V
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
FeaTures
DescripTion
High Voltage Surge
Stopper with Current Limit
4A, 12V Overvoltage Output Regulator with 150V Surge Protection
Overvoltage Protector Regulates
Output at 27V During Transient
applicaTions
n
Withstands Surges Over 100V with V
CC
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
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.
0.1µF
10Ω
10mΩ
FDB33N25
V
IN
12V
4363 TA01
LT4363-2
GND
TMR
OUT
GATE SNS
UV
SHDN
OV
FAULT
OUTPUT
CLAMP
AT 16V
ENOUT
FLT
FB
1k
SMAJ58A
22µF
0.1µF
V
CC
DC/DC
CONVERTER
GND
SHDN
V
CC
4.99k
127k
49.9k
57.6k
