LT1640L/LT1640H
Negative Voltage
Hot Swap Controller
FEATURES
s
s
s
s
s
s
s
DESCRIPTIO
Allows Safe Board Insertion and Removal
from a Live – 48V Backplane
Operates from –10V to – 80V
Programmable Inrush Current
Programmable Electronic Circuit Breaker
Programmable Overvoltage Protection
Programmable Undervoltage Lockout
Power Good Control Output
APPLICATIO S
s
s
s
Central Office Switching
– 48V Distributed Power Systems
Negative Power Supply Control
The LT
®
1640L/LT1640H is an 8-pin, negative voltage Hot
Swap
TM
controller that allows a board to be safely inserted
and removed from a live backplane. Inrush current 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
(LT1640L) or PWRGD (LT1640H) signal can be used to
directly enable a power module. The LT1640L is designed
for modules with a low enable input and the LT1640H for
modules with a high enable input.
The LT1640L/LT1640H is available in 8-pin PDIP and SO
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
GND
GND
R4
†
562k
1%
R5
†
9.09k
1%
UV = 37V
R6
†
10k
1%
8
V
DD
3
UV
LT1640L
2
OV
V
EE
4
SENSE
5
GATE
6
(SHORT PIN)
PWRGD
1
INRUSH
CURRENT
1A/DIV
DRAIN
7
1N4148
OV = 71V
*
GATE – V
EE
10V/DIV
3
– 48V
1
R1
0.02Ω
5%
2
†
C1
†
150nF
25V
4
R2
10Ω
5%
R3
†
†
18k C2
3.3nF
5%
100V
2
ON/OFF
9
V
OUT+
8
SENSE
+
7
TRIM
6
SENSE
–
4
5
V
OUT–
V
IN–
1
V
IN+
LUCENT
JW050A1-E
5V
DRAIN
50V/DIV
V
EE
50V/DIV
Q1
IRF530
* DIODES INC. SMAT70A
†
THESE COMPONENTS ARE APPLICATION
SPECIFIC AND MUST BE SELECTED BASED
UPON OPERATING CONDITIONS AND DESIRED
PERFORMANCE. SEE APPLICATIONS
INFORMATION.
C3
0.1µF
100V
+
C4
100µF
100V
+
C5
100µF
16V
CONTACT
BOUNCE
5ms/DIV
1640 F06b
1640 TA01
U
Input Inrush Current
1640lhfb
U
U
1
LINER [ LINEAR TECHNOLOGY ]
