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
10Ω
5%
R3
†
18k
5%
R4
†
562k
1%
R5
†
9.09k
1%
R6
†
10k
1%
R1
†
0.02Ω
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
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APPLICATIO S
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TYPICAL APPLICATIO
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