LTC4251B/LTC4251B-1/
LTC4251B-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 4251B/LTC4251B-1/LTC4251B-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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Improved Ruggedness Shunt Regulator
Programmable undervoltage and overvoltage detectors
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Programmable Timer
disconnect the load whenever the input supply exceeds
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Programmable Undervoltage/Overvoltage Protection
the desired operating range. The supply input is shunt
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Low Profile 6-Lead SOT-23 (ThinSOT) Package
regulated, allowing safe operation with very high supply
voltages. A multifunction timer delays initial start-up and
controls the circuit breakers response time.
APPLICATIONS
The LTC4251B UV/OV thresholds are designed to match
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Hot Board Insertion
the standard telecom operating range of 43V to 75V. The
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Electronic Circuit Breaker
LTC4251B-1 UV/OV thresholds extend the operating range
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48V Distributed Power Systems
to encompass 36V to 72V. The LTC4251B-2 implements
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Negative Power Supply Control
a UV threshold of 43V only. The LTC4251B improves the
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Central Office Switching
ruggedness of the LTC4251 shunt regulator.
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Programmable Current Limiting Circuit
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
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High Availability Servers
Hot Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks
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are the property of their respective owners.
Disk Arrays
TYPICAL APPLICATION
48V, 2.5A Hot Swap Controller Start-Up Behavior
48RTN
R *
IN
+
48RTN
10k
GATE
C
L
LOAD
(SHORT PIN)
500mW
5V/DIV
100F
R1
V
OUT
402k
C
D
IN IN
V
IN
1%
1F
DDZ13B**
Q1 SENSE
UV/OV GATE
IRF530S 2.5A/DIV
C1
LTC4251B
10nF
3
TIMER SENSE
R2 1
R
C
V R
32.4k EE S V
OUT
10
0.02
1% 20V/DIV
C
C
T C
18nF 2
150nF
4
4251b12 TA01a
48V 4251b12 TA01b
1ms/DIV
*TWO 0.25W RESISTORS IN SERIES FOR
R ON THE PCB ARE RECOMMENDED.
IN
**DIODES, INC.
RECOMMENDED FOR HARSH ENVIRONMENTS
4251b12f
1LTC4251B/LTC4251B-1/
LTC4251B-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 LTC4251B-2
LTC4251BC/LTC4251BC-1/LTC4251BC-2 ....0C to 70C
T = 125C, = 192C/W
JMAX JA
LTC4251BI/LTC4251BI-1/LTC4251BI-2 .. 40C to 85C
Storage Temperature Range .................. 65C to 150C
Lead Temperature (Soldering, 10 sec) ...................300C
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4251BCS6#TRMPBF LTC4251BCS6#TRPBF LTGCT 6-Lead Plastic SOT-23 0C to 70C
LTC4251BIS6#TRMPBF LTC4251BIS6#TRPBF LTGCT 6-Lead Plastic SOT-23 40C to 85C
LTC4251BCS6-1#TRMPBF LTC4251BCS6-1#TRPBF LTGDV 6-Lead Plastic SOT-23 0C to 70C
LTC4251BIS6-1#TRMPBF LTC4251BIS6-1#TRPBF LTGDV 6-Lead Plastic SOT-23 40C to 85C
LTC4251BCS6-2#TRMPBF LTC4251BCS6-2#TRPBF LTGDW 6-Lead Plastic SOT-23 0C to 70C
LTC4251BIS6-2#TRMPBF LTC4251BIS6-2#TRPBF LTGDW 6-Lead Plastic SOT-23 40C to 85C
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to: