LTC4253 Datasheet, PDF (1/32 Pages) Linear Technology – -48V Hot Swap Controller with Sequencer

FEATURES
s _{Allows Safe Board Insertion and Removal from a}
Live – 48V Backplane
s _{Floating Topology Permits Very High Voltage}
Operation
s _{Programmable Analog Current Limit with Breaker}
Timer Ideal for Two Battery Feeds
s _{Fast Response Time Limits Peak Fault Current}
s _{Latchoff After Fault}
s _{Three Sequenced Power Good Outputs}
s _{Programmable Soft-Start Current Limit}
s _{Programmable Timer with Drain Voltage}
Accelerated Response
s _{Programmable Undervoltage/Overvoltage Protection}
U
APPLICATIO S
s _{Hot Board Insertion}
s _{Electronic Circuit Breaker}
s _{– 48V Distributed Power Systems}
s _{Negative Power Supply Control}
s _{Central Office Switching}
s _{Programmable Current Limiting Circuit}
s _{High Availability Servers}
s _{Disk Arrays}
LTC4253
– 48V Hot Swap Controller
with Sequencer
DESCRIPTIO
The LTC^®4253 negative voltage Hot Swap^TM controller
allows a board to be safely inserted and removed from a
live backplane. Output current is controlled 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.
The LTC4253 latches off after a circuit fault.
Programmable undervoltage and overvoltage detectors
disconnect the load whenever the input supply exceeds
the desired operating range. The LTC4253’s supply input
is shunt-regulated, allowing safe operation with very high
supply voltages. A multifunction timer delays initial start-
up and controls the circuit breaker’s response time. The
circuit breaker’s response time can be accelerated by
sensing excessive MOSFET drain voltage, keeping the
MOSFET within safe operating area (SOA). A program-
mable soft-start circuit controls MOSFET inrush current at
start-up.
Three power good outputs are sequenced by a program-
mable timer to enable external power modules at start-up
or disable them if the circuit breaker trips. The LTC4253 is
available in 16-pin SSOP.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
– 48V RTN
(LONG PIN)
R_IN
2.8k
16k(1/4W)/6
– 48V/2.5A Hot Swap Controller
C2 ⁺
V_IN
100µF
C_IN
R3
1µF
5.6k
R4
5.6k
R5
C3
5.6k
0.1µF
POWER
MODULE 1
EN
– 48V RTN
(SHORT PIN)
R1
402k
1%
RESET
R2
32.4k
1%
B3100*
– 48V A
(LONG PINS) _B3100*
– 48V B
4
V_IN
†
†
LTC4253
11
3
OV
PWRGD1
12
2
UV
PWRGD2
5
16
RESET PWRGD3
C1 10nF
15
EN3
1
EN2
C_SS 68nF
6
EN2
10
R_D 1M
SS
DRAIN
14
SQTIMER
9
GATE
Q1
IRF530S
V_IN
C_SQ
13
TIMER
7
SENSE
0.1µF
V_EE
R_C
10Ω RS
†
C_T
8
C_C
0.02Ω
0.33µF
18nF
†
EN3
R6 POWER
MODULE 1
OUTPUT
POWER
MODULE 2
EN
POWER
MODULE 2
OUTPUT
V_IN
R7
†
*DIODES, INC.
†_MOC207
POWER
MODULE 3
EN
4253 TA01
4253f
1