1
LTC1421/LTC1421-2.5
Hot Swap Controller
s
Allows Safe Board Insertion and Removal from a
Live Backplane
s
System Reset and Power Good Control Outputs
s
Programmable Electronic Circuit Breaker
s
User Programmable Supply Voltage Power-Up Rate
s
High Side Driver for Two External N-Channels
s
Controls Supply Voltages from 3V to 12V
s
Connection Inputs Detect Board Insertion or Removal
s
Undervoltage Lockout
s
Power-On Reset Input
s
Hot Board Insertion
s
Electronic Circuit Breaker
The LTC
?/DIV>
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.
The LTC1421/LTC1421-2.5 are available in 24-pin SO and
SSOP packages.
10
9
14
13
8
11
15
6
7
RAMP
CPON
COMP
COMP
+
REF
FB
COMPOUT
PWRGD
RESET
2
24
4
3
1
CON2
AUXV
CC
FAULT
POR
CON1
V
CCLO
SETLO GATELO V
OUTLO
LTC1421
GND
DISABLE
V
CCHI
SETHI  GATEHI V
OUTHI
16
C2
0.1礔
C1
1礔
R5
16k
5%
Q1
MTB50N06E
R1
0.005&
17
18
19
20
21
22
5
12
23
R3
1k
D1
R6
20k
1%
R4
20k
5%
R7
7.15k
1%
Q2
1/2 Si4936DY
Q3
1/2 Si4936DY
C3
0.47礔
R2
0.025&
+
C
LOAD
C
LOAD
C
LOAD
V
EE
12V
1A
V
DD
12V
1A
V
CC
5V
5A
+
I/O
I/O
RESET
BEA
BEB
GND
1
13
12
礟
QS3384
QuickSwitch
?/DIV>
QuickSwitch IS A REGISTERED TRADEMARK
OF QUALITY SEMICONDUCTOR CORPORATION.
1421 TA01
DATA BUS
PC BOARD
BACKPLANE
DATA
BUS
GND
POR
FAULT
V
CC
V
DD
V
EE
V
CC
1礔
4
3
2
1
4
3
2
1
10k
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
DESCRIPTIO
FEATURES
APPLICATIO S
TYPICAL APPLICATIO