LTC4251/LTC4251-1/
LTC4251-2
Negative Voltage
Hot Swap Controllers in SOT-23
FEATURES DESCRIPTION
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Allows Safe Board Insertion and Removal from a The LTC 4251/LTC4251-1/LTC4251-2 negative voltage
Live 48V Backplane Hot Swap controllers allow a board to be safely inserted
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Floating Topology Permits Very High Voltage and removed from a live backplane. Output current is con-
Operation trolled by three stages of current limiting: a timed circuit
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Programmable Analog Current Limit with Circuit breaker, active current limiting and a fast feedforward path
Breaker Timer that limits peak current under worst-case catastrophic
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Fast Response Time Limits Peak Fault Current fault conditions.
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Programmable Timer
Programmable undervoltage and overvoltage detectors
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Programmable Undervoltage/Overvoltage Protection
disconnect the load whenever the input supply exceeds
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Low Profile (1mm) ThinSOT Package
the desired operating range. The supply input is shunt
regulated, allowing safe operation with very high supply
voltages. A multifunction timer delays initial start-up and
APPLICATIONS
controls the circuit breakers response time.
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Hot Board Insertion
The LTC4251 UV/OV thresholds are designed to match the
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Electronic Circuit Breaker
standard telecom operating range of 43V to 75V. The
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48V Distributed Power Systems
LTC4251-1 UV/OV thresholds extend the operating range
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Negative Power Supply Control
to encompass 36V to 72V. The LTC4251-2 implements
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Central Office Switching
a UV threshold of 43V only.
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Programmable Current Limiting Circuit
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High Availability Servers
All parts are available in the 6-Pin SOT-23 package.
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Disk Arrays
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
TYPICAL APPLICATION
48V, 2.5A Hot Swap Controller Start-Up Behavior
48RTN
R *
IN
+
48RTN 10k
C
GATE
L
LOAD
(SHORT PIN) 500mW
100F
5V/DIV
R1
V
OUT
402k
C
D IN
IN
V
IN
1%
1F
DDZ13B**
Q1
SENSE
UV/OV GATE
IRF530S
2.5A/DIV
C1
LTC4251
10nF
3
TIMER SENSE
R2 1
R
C
R
V
32.4k EE S
V
OUT
10
0.02
1%
20V/DIV
C C
C
T
2
150nF 18nF
4
425112 TA01
48V
425112 TA02
1ms/DIV
*TWO 0.25W RESISTORS IN SERIES FOR
R ON THE PCB ARE RECOMMENDED.
IN
**DIODES, INC.
RECOMMENDED FOR HARSH ENVIRONMENTS
425112fd
1
For more information www.linear.com/4251LTC4251/LTC4251-1/
LTC4251-2
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Note 1), All Voltages are Referred to V
EE
Current into V (100s Pulse) .............................100mA
IN
Minimum V Voltage ............................................ 0.3V
IN
TOP VIEW
Gate, UV/OV, Timer Voltage........................ 0.3V to 16V
SENSE 1 6 GATE
Sense Voltage ............................................ 0.6V to 16V
V 2 5 UV/OV*
EE
Current Out of Sense Pin (20s Pulse) .............. 200mA
V 3 4 TIMER
IN
Maximum Junction Temperature .......................... 125C
S6 PACKAGE
Operating Temperature Range
6-LEAD PLASTIC SOT-23
*UV FOR LTC4251-2
LTC4251C/LTC4251-1C/LTC4251-2C ........ 0C to 70C
T = 125C, = 256C/W
JMAX JA
LTC4251I/LTC4251-1I/LTC4251-2I ........40C to 85C
Storage Temperature Range .................. 65C to 150C
Lead Temperature (Soldering, 10 sec) ...................300C
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4251CS6#PBF LTC4251CS6#TRPBF LTUQ 6-Lead Plastic SOT-23 0C to 70C
LTC4251IS6#PBF LTC4251IS6#TRPBF LTUR 6-Lead Plastic SOT-23 40C to 85C
LTC4251-1CS6#PBF LTC4251-1CS6#TRPBF LTQU 6-Lead Plastic SOT-23 0C to 70C
LTC4251-1IS6#PBF LTC4251-1IS6#TRPBF LTQV 6-Lead Plastic SOT-23 40C to 85C
LTC4251-2CS6#PBF LTC4251-2CS6#TRPBF LTK6 6-Lead Plastic SOT-23 0C to 70C
LTC4251-2IS6#PBF LTC4251-2IS6#TRPBF LTAAZ 6-Lead Plastic SOT-23 40C to 85C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: