Final Electrical Specifications
LT1641
Positive High Voltage
Hot Swap Controller
August 1999
FEATURES
s
s
s
s
s
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DESCRIPTIO
Allows Safe Board Insertion and Removal from a
Live Backplane
Controls Supply Voltage from 9V to 80V
Programmable Analog Foldback Current Limiting
High Side Drive for an External N-Channel
Automatic Retry or Latched Operation Mode
User Programmable Supply Voltage Power-Up Rate
Undervoltage Lockout
Overvoltage Protection
The LT
®
1641 is an 8-pin Hot Swap
TM
controller that allows
a board to be safely inserted and removed from a live
backplane. Using an external N-channel pass transistor,
the board supply voltage can be ramped up at a program-
mable rate. A high side switch driver controls an N-channel
gate for supply voltages ranging from 9V to 80V.
The chip features a programmable analog foldback cur-
rent limit circuit. If the chip remains in current limit for
more than a programmable time, the N-channel pass
transistor latches off and is optionally set to automatically
restart after a time-out delay.
The PWRGD output indicates when the output voltage,
sensed by the FB pin, is within tolerance. The ON pin
provides programmable undervoltage lockout.
The LT1641 is available in the 8-lead SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
APPLICATIO S
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Hot Board Insertion
Electronic Circuit Breaker
Industrial High Side Switch/Circuit Breaker
24V/48V Industrial/Alarm Systems
TYPICAL APPLICATIO
24V Input Voltage Application
V
IN
24V
R1
49.9k
1%
R
S
0.01Ω
Q1
IRF530
V
OUT
R5
10Ω
5%
D1
CMPZ
5248B
C1
R6, 10nF
1k, 5%
8
V
CC
1
ON
LT1641
R2
3.4k
1%
TIMER
5
GND
C2
0.68µF
GND
4
1641 TA01
R3
59k
1%
7
SENSE
6
GATE
FB
2
R4
3.57k
1%
3
R7
24k
5%
PWRGD
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
C
L
PWRGD
U
U
1
LINER [ LINEAR TECHNOLOGY ]
