LTC4253A_15 Datasheet, PDF (1/34 Pages) Linear Technology – 48V Hot Swap Controllers with Sequencer

LTC4253/LTC4253A
–48V Hot Swap Controllers
with Sequencer
FEATURES
n _{Allows Safe Board Insertion and Removal from a}
Live –48V Backplane
n _{Floating Topology Permits Very High Voltage}
Operation
n _{Adjustable Analog Current Limit with Breaker Timer}
Ideal for Two Battery Feeds
n _{Fast Response Time Limits Peak Fault Current}
n _{Adjustable Undervoltage/Overvoltage Protection}
with ±1% Threshold Accuracy (LTC4253A)
n _{Three Sequenced Power Good Outputs}
n _{Adjustable Soft-Start Current Limit}
n _{Adjustable Timer with Drain Voltage Accelerated}
Response
n _{Latchoff After Fault}
n _{Available in a 16-Pin SSOP Package}
APPLICATIONS
n _{–48V Distributed Power Systems}
n _{Negative Power Supply Control}
n _{Central Office Switching}
n _{High Availability Servers}
n _{Disk Arrays}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot
Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of
their respective owners.
DESCRIPTION
The LTC^®4253/LTC4253A negative voltage Hot Swap™
controllers allow 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 condi-
tions. The LTC4253/LTC4253A latch off after a circuit fault.
Adjustable undervoltage and overvoltage detectors dis-
connect the load whenever the input supply exceeds the
desired operating range. The LTC4253/LTC4253A’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 its safe operating area (SOA). An adjustable
soft-start circuit controls MOSFET inrush current at start-up.
Three power good outputs are sequenced by an adjustable
timer and two ENABLE inputs to enable external power
modules at start-up or disable them if the circuit breaker
trips. The LTC4253A features tight ±1% undervoltage/
overvoltage threshold accuracy. The LTC4253/LTC4253A
are available in a 16-pin SSOP.
TYPICAL APPLICATION
– 48V/2.5A Hot Swap Controller
– 48V RTN
2.5k
1µF
15k(1/4W)/6 _VIN
– 48V RTN
5.6k
5.6k
402k
1% ^10nF
D_IN††
DDZ13B*
EN2 EN3 V_IN
LTC4253
RESET
32.4k
1%
B3100*
– 48V A
B3100*
– 48V B
68nF
0.1µF
0.33µF
UV
PWRGD1
OV
PWRGD2
SS
PWRGD3
DRAIN
SQTIMER
GATE
TIMER
SENSE
V_EE
†
†
1M
IRF530S
10Ω
18nF
0.02Ω
+
100µF
5.6k
†
LOAD1
EN
LOAD2
EN
LOAD3
EN
4253 TA01
*DIODES, INC.
†_MOC207
††_{RECOMMENDED FOR HARSH ENVIRONMENTS.}
GATE
10V
SS
1V
SENSE
50mV
V_OUT
50V
For more information www.linear.com/4253
Start-Up Behavior
1ms/DIV
4253 TA01b
425353aff
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