Linear Technology LT4363 Datasheet

FeaTures
Withstands Surges Over 100V with V
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,
n
LT4363-2
Available in 12-Pin (4mm × 3mm) DFN, 12-Pin
n
MSOP and 16-Pin SO Packages
applicaTions
Automotive/Avionic/Industrial Surge Protection
n
Hot Swap™/Live Insertion
n
High Side Switch for Battery Powered Systems
n
Intrinsic Safety Applications
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No R , ThinSOT and Hot Swap are trademarks of Linear Technology Corporation. All other
SENSE
trademarks are the property of their respective owners.
Typical applicaTion
4A, 12V Overvoltage Output Regulator with 150V Surge Protection
V
IN
12V
1k
0.1µF
V
CC
127k
SMAJ58A
SHDN
UV
49.9k
OV
Clamp
CC
10m
FDB33N25
10
57.6k
GATE SNS OUT
FB
4.99k
LT4363-2
ENOUT
FLT FAULT
GND TMR
4363 TA01
0.1µF
For more information
High Voltage Surge
Stopper with Current Limit
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.
OUTPUT
CLAMP
22µF
AT 16V
V
IN
20V/DIV
V
CC
DC/DC
V
CONVERTER OUT
20V/DIV
SHDN
GND
www.linear.com/LT4363
LT4363
Overvoltage Protector Regulates
Output at 27V During Transient
C
80V INPUT SURGE
TMR
I
LOAD
12V
27V ADJUSTABLE CLAMP
12V
100ms/DIV
= 6.8µF
= 500mA
4363 TA01b
4363fb
1