LTC1421/LTC1421-2.5
Hot Swap Controller
FEATURES
s
s
s
s
s
s
s
s
s
DESCRIPTION
The LTC
®
1421/LTC1421-2.5 are Hot Swap
TM
controllers
that allow a board to be safely inserted and removed from a
live backplane. Using external N-channel pass transistors,
the board supply voltages can be ramped up at a program-
mable rate. Two high side switch drivers control the N-
channel gates for supply voltages ranging from 3V to 12V.
A programmable electronic circuit breaker protects against
shorts. Warning signals indicate that the circuit breaker
has tripped, a power failure has occurred or that the switch
drivers are turned off. The reset output can be used to
generate a system reset when the power cycles or a fault
occurs. The two connect inputs can be used with stag-
gered connector pins to indicate board insertion or re-
moval. The power-on reset input can be used to cycle the
board power or clear the circuit breaker.
The trip point of the ground sense comparator is set at
0.1V for LTC1421 and 2.5V for LTC1421-2.5.
Allows Safe Board Insertion and Removal from a
Live Backplane
System Reset and Power Good Control Outputs
Programmable Electronic Circuit Breaker
User Programmable Supply Voltage Power-Up Rate
High Side Driver for Two External N-Channels
Controls Supply Voltages from 3V to 12V
Connection Inputs Detect Board Insertion or Removal
Undervoltage Lockout
Power-On Reset Input
APPLICATIONS
s
s
Hot Board Insertion
Electronic Circuit Breaker
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
The LTC1421/LTC1421-2.5 are available in 24-pin SO and
SSOP packages.
TYPICAL APPLICATION
Q3
1/2 Si4936DY
C3
0.47µF
V
EE
V
DD
R1
0.005Ω
V
CC
STAGGERED CONNECTOR
Q2
R2
0.025Ω 1/2 Si4936DY
Q1
MTB50N06E
D1
R3
1k
23
22
21
20
19
18
17
16
10
9
14
13
8
11
15
6
7
V
CCLO
SETLO GATELO V
OUTLO
V
CCHI
2
CON2
24
AUXV
CC
C1
1µF
4
FAULT
SETHI GATEHI V
OUTHI
RAMP
CPON
COMP
–
COMP
+
REF
FB
COMPOUT
PWRGD
RESET
C2
0.1µF
R5
16k
5%
R6
20k
1%
1µF
LTC1421
R7
7.15k
1%
µP
I/O
I/O
RESET
FAULT
POR
3
POR
1
CON1
GND
12
DISABLE
5
1
BEA V
CC
13
BEB
12
GND
QS3384
QuickSwitch
®
GND
DATA BUS
1421 TA01
DATA
BUS
QuickSwitch IS A REGISTERED TRADEMARK
OF QUALITY SEMICONDUCTOR CORPORATION.
BACKPLANE
PC BOARD
+
R4
20k
5%
U
U
U
C5
220µF
V
EE
– 12V
1A
V
DD
12V
1A
V
CC
5V
5A
+
+
C3
220µF
C4
220µF
1
LINER [ LINEAR TECHNOLOGY ]
