LT4256-3 Datasheet, PDF (1/20 Pages) Linear Technology – Positive High Voltage Hot Swap Controller with Open-Circuit Detect

FEATURES
s _{Allows Safe Board Insertion and Removal from a}
Live Backplane
s _{Controls Supply Voltage from 10.8V to 80V}
s _{Foldback Current Limiting}
s _{Open Circuit and Overcurrent Fault Detect}
s _{Drives an External N-Channel MOSFET}
s _{Automatic Retry or Latched Off Operation}
After Overcurrent Fault
s _{Programmable Supply Voltage Power-Up Rate}
s _{Open MOSFET Detection}
s _{1% Over and Undervoltage Detection Accuracy}
s _{Available in a 16-Lead SSOP Package}
U
APPLICATIO S
s _{Hot Board Insertion}
s _{Electronic Circuit Breaker/Power Bussing}
s _{Industrial High Side Switch/Circuit Breaker}
s _{24V/48V Industrial/Alarm Systems}
s _{Ideally Suited for 12V, 24V and 48V Distributed}
Power Systems
s _{48V Telecom Systems}
LT4256-3
Positive High Voltage
Hot Swap Controller
with Open-Circuit Detect
DESCRIPTIO
The LT^®4256-3 is a high voltage Hot Swap^TM controller that
allows a board to be safely inserted and removed from a
live backplane. An internal driver controls the high side
N-channel MOSFET gate for supply voltages ranging from
10.8V to 80V. The part features an open-circuit detect
(OPEN) output that indicates abnormally low load current
conditions.
The LT4256-3 also features an adjustable analog foldback
current limit. If the supply remains in current limit for more
than a programmable time, the N-channel MOSFET shuts
off, the PWRGD output asserts low and the LT4256-3
either automatically restarts after a time-out delay or
latches off until the UV pin is cycled low (depending on the
status of the RETRY pin).
The PWRGD output indicates when the output voltage
rises above a programmed level. An external resistor
string from V_CC provides programmable undervoltage and
overvoltage protection.
The LT4256-3 is available in a 16-lead SSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
48V, 2A Hot Swap Controller
V_IN
48V
(SHORT PIN)
0.020Ω
SMAT70A
IRF540
CMPZ5241BS
11V
0.01µF
GND
64.9k
4.02k
4.02k
V_CC SENSE
10Ω
UV
GATE
LT4256-3
V_OUT
FB
OV
OPEN PWRGD
TIMER RETRY
33nF
GND
10nF
100Ω
UV = 36V
OV = 73V
PWRGD = 40V
36.5k
4.02k
V_OUT
+
48V
2A
C_L
V_IN
50V/DIV
51k
V_OUT
50V/DIV
INRUSH
CURRENT
500mA/DIV
PWRGD
4256 TA01
PWRGD
50V/DIV
LT4256-3 Start-Up Behavior
CONTACT BOUNCE
2.5ms/DIV
42563 TA02
42563f
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