LTC1421 Datasheet, PDF (1/24 Pages) Linear Technology – Hot Swap Controller

LTC1421/LTC1421-2.5
Hot Swap Controller
FEATURES
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}
U
APPLICATIONS
s _{Hot Board Insertion}
s _{Electronic Circuit Breaker}
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
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.
The LTC1421/LTC1421-2.5 are available in 24-pin SO and
SSOP packages.
TYPICAL APPLICATION
V_EE
V_DD
V_CC
FAULT
POR
GND
DATA
BUS
BACKPLANE PC BOARD
R1
Q1
0.005Ω MTB50N06E
C3
0.47µF
R2
Q2
0.025Ω 1/2 Si4936DY
D1
23 22 21
20 19 18 17 16
V_CCLO SETLO GATELO V_OUTLO V_CCHI SETHI GATEHI V_{OUTHI 10}
R3
1k
2
CON2
RAMP
9
CPON
24
C1 ^AUXVCC
1µF
LTC1421
COMP ^{– 14}
COMP ^{+ 13}
8
REF
4
11
FAULT
FB
15
COMPOUT
3
6
POR
PWRGD
1
7
CON1 _GND
DISABLE
RESET
Q3
1/2 Si4936DY
R4
20k
C5
+ 220µF
5%
+ _C3
220µF
R6 ⁺
C2
20k
0.1µF _R5 ^1%
16k
5%
C4
220µF
1µF
R7
7.15k
1%
µP
I/O
I/O
RESET
V_EE
– 12V
1A
V_DD
12V
1A
V_CC
5V
5A
12
5
1
13
BEA
BEB
V_CC
12 _GND
DATA BUS
QS3384
QuickSwitch^®
QuickSwitch IS A REGISTERED TRADEMARK
OF QUALITY SEMICONDUCTOR CORPORATION.
1421 TA01
1