Datasheet

1
LT1640AL/LT1640AH
Negative Voltage
Hot Swap Controller
Allows Safe Board Insertion and Removal
from a Live –48V Backplane
Operates from –10V to –80V
Programmable Inrush Current
Allows 50mA of Reverse Drain Pin Current
Programmable Electronic Circuit Breaker
Programmable Overvoltage Protection
Programmable Undervoltage Lockout
Power Good Control Output
The LT
®
1640AL/LT1640AH are 8-pin, negative voltage
Hot Swap
TM
controllers that allow a board to be safely
inserted and removed from a live backplane. Inrush cur-
rent is limited to a programmable value by controlling the
gate voltage of an external N-channel pass transistor. The
pass transistor is turned off if the input voltage is less than
the programmable undervoltage threshold or greater than
the overvoltage threshold. A programmable electronic
circuit breaker protects the system against shorts. The
PWRGD (LT1640AL) or PWRGD (LT1640AH) signal can
be used to directly enable a power module. The LT1640AL
is designed for modules with a low enable input and the
LT1640AH for modules with a high enable input.
The LT1640AL/LT1640AH are available in 8-pin PDIP and
SO packages.
Central Office Switching
48V Distributed Power Systems
Negative Power Supply Control
Hot Swap is a trademark of Linear Technology Corporation.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Input Inrush Current
CONTACT
BOUNCE
1640A F07b
V
EE
V
DD
LT1640AL
SENSE
C1
150nF
25V
C2
3.3nF
100V
C3
0.1µF
100V
C4
100µF
100V
Q1
IRF530
R2
10
5%
R3
18k
5%
R4
562k
1%
R5
9.09k
1%
R6
10k
1%
R1
0.02
5%
4
OV
GND
GND
(SHORT PIN)
3
2
48V
OV = 71V
*
* DIODES INC. SMAT70A
THESE COMPONENTS ARE APPLICATION
SPECIFIC AND MUST BE SELECTED BASED
UPON OPERATING CONDITIONS AND DESIRED
PERFORMANCE. SEE APPLICATIONS
INFORMATION.
UV = 37V
UV
56
8
7
1
GATE DRAIN
PWRGD
1640A TA01
V
OUT
+
SENSE
+
TRIM
SENSE
V
OUT
V
IN
ON/OFF
LUCENT
JW050A1-E
V
IN
+
2
9
5V
8
7
6
5
1
4
+
C5
100µF
16V
+
43
21
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U

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