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LTC4251-1_15 Datasheet, PDF (1/24 Pages) Linear Technology – Negative Voltage Hot Swap Controllers in SOT-23 | |||
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LTC4251/LTC4251-1/
LTC4251-2
Negative Voltage
Hot Swap Controllers in SOT-23
FEATURES
n Allows Safe Board Insertion and Removal from a
Live â48V Backplane
n Floating Topology Permits Very High Voltage
Operation
n Programmable Analog Current Limit with Circuit
Breaker Timer
n Fast Response Time Limits Peak Fault Current
n Programmable Timer
n Programmable Undervoltage/Overvoltage Protection
n Low Profile (1mm) ThinSOT⢠Package
APPLICATIONS
n Hot Board Insertion
n Electronic Circuit Breaker
n â48V Distributed Power Systems
n Negative Power Supply Control
n Central Office Switching
n Programmable Current Limiting Circuit
n High Availability Servers
n Disk Arrays
DESCRIPTION
The LTC®4251/LTC4251-1/LTC4251-2 negative voltage
Hot Swap⢠controllers allow a board to be safely inserted
and removed from a live backplane. Output current is con-
trolled by three stages of current limiting: a timed circuit
breaker, active current limiting and a fast feedforward path
that limits peak current under worst-case catastrophic
fault conditions.
Programmable undervoltage and overvoltage detectors
disconnect the load whenever the input supply exceeds
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
controls the circuit breakerâs response time.
The LTC4251 UV/OV thresholds are designed to match the
standard telecom operating range of â 43V to â75V. The
LTC4251â1 UV/OV thresholds extend the operating range
to encompass â36V to â72V. The LTC4251-2 implements
a UV threshold of â43V only.
All parts are available in the 6-Pin SOT-23 package.
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
â48V, 2.5A Hot Swap Controller
â48RTN
â48RTN
(SHORT PIN)
R1
402k
1%
R2
32.4k
1%
RIN*
10k
500mW
DINâ
DDZ13B**
VIN
UV/OV GATE
C1
10nF
LTC4251
TIMER SENSE
VEE
CT
150nF
â 48V
*TWO 0.25W RESISTORS IN SERIES FOR
RIN ON THE PCB ARE RECOMMENDED.
**DIODES, INC.
â RECOMMENDED FOR HARSH ENVIRONMENTS
CL +
100µF
CIN
1µF
LOAD
VOUT
Q1
IRF530S
RC
10Ω
CC
18nF
3
1
RS
0.02Ω
2
4 425112 TA01
GATE
5V/DIV
SENSE
2.5A/DIV
VOUT
20V/DIV
For more information www.linear.com/4251
Start-Up Behavior
1ms/DIV
425112 TA02
425112fd
1
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