LTC4253A-ADJ Datasheet, PDF (1/32 Pages) Linear Technology – -48V Hot Swap Controller with Sequencer

LTC4253A-ADJ
– 48V Hot Swap Controller
with Sequencer
FEATURES
■ _{Allows Safe Board Insertion and Removal from a}
Live – 48V Backplane
■ _{Floating Topology Permits Very High Voltage}
Operation
■ _{Adjustable Analog Current Limit with Breaker Timer}
■ _{Fast Response Time Limits Peak Fault Current}
■ _{Adjustable Undervoltage/Overvoltage Protection}
with ±1% Threshold Accuracy
■ _{Three Sequenced Power Good Outputs}
■ _{Adjustable Soft-Start Current Limit}
■ _{Adjustable Timer with Drain Voltage Accelerated}
Response
■ _{Latchoff After Fault}
■ _{Available in 20-Pin SSOP and 20-Pin (4mm × 4mm)}
QFN Packages
U
APPLICATIO S
■ _{– 48V Distributed Power Systems}
■ _{Negative Power Supply Control}
■ _{Central Office Switching}
■ _{High Availability Servers}
■ _{Disk Arrays}
DESCRIPTIO
The LTC^®4253A-ADJ negative voltage Hot Swap^TM con-
troller 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 condi-
tions. The LTC4253A-ADJ latches off after a circuit fault.
Undervoltage and overvoltage detectors with adjustable
thresholds and hystereses disconnect the load whenever
the input supply exceeds the desired operating range. The
LTC4253A-ADJ’s supply input is shunt-regulated, allowing
safe operation with very high supply voltages. A multifunc-
tion 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. An adjustable soft-start circuit controls MOSFET
inrush current at start-up.
Three power good outputs can be sequenced to enable
external power modules at start-up or disable them if the
circuit breaker trips. The LTC4253A-ADJ is available in
20-pin SSOP and 20-pin (4mm × 4mm) QFN packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Patent pending.
TYPICAL APPLICATIO
– 48V/2.5A Hot Swap Controller
– 48V RTN
– 48V RTN
1µF
255k _10nF
1%
2.5k
15k(1/4W)/6 _VIN
5.6k
5.6k
1.24k
1%
EN2 EN3 V_IN
LTC4253A-ADJ
RESET
2.1k
1%
0.536k
1%
UVL
UV
OVL
OV
33nF
SS
PWRGD1
PWRGD2
PWRGD3
†
†
– 48V A
20k
1%
B3100*
B3100*
– 48V B
0.1µF
0.68µF
SQTIMER
TIMER
SEL
DRAIN
GATE
SENSE
V_EE
1M
IRF530S
10Ω
10nF
0.02Ω
+
100µF
5.6k
†
LOAD1
EN
LOAD2
EN
LOAD3
EN
4253A TA01
*DIODES, INC.
†_MOC207
GATE
10V
SS
1V
SENSE
50mV
V_OUT
50V
Start-Up Behavior
1ms/DIV
4253A TA01b
4253a-adjf
1