LTC1421 Datasheet, PDF (17/24 Pages) Linear Technology – Hot Swap Controller

LTC1421/LTC1421-2.5
APPLICATIONS INFORMATION
5V Only Applications
The LTC1421 may be used in 5V only applications as shown
in Figure 18. A soft reset can be generated from the
backplane via an open-collector inverter driving the FB (Pin
11) or by a push button to ground. A hard power reset is
generated from the backplane via an open-collector inverter
driving the POR (Pin 3). A hard reset cycles the power on
the board or resets the electronic circuit breaker. The
comparator is used to monitor the board supply voltage and
will pull the POWERGOOD signal low as long as the supply
remains above 4.65V. Note that a soft reset will not affect
the POWERGOOD signal. The FAULT signal is also moni-
tored to determine that the circuit breaker has tripped.
– 48V and 24V Applications
The LTC1421 may be used in – 48V applications as shown
in Figure 19. The LTC1421 provides the hot insertion
protection, while the 5V supply is generated by a power
5V
POWERGOOD
FAULT
SOFT RESET
HARD RESET
5V
10k
5V
10k
1/6
LS7004
R1
0.005Ω
Q1
1W MTB50N06E
2
24
+
C1
1µF
15
23 22 21 20 19 18 17 16
10
7
14
LTC1421
13
8
11
1
12 5 9 6 3
5V
C2
2200µF
C2
1µF
R2
28k
1%
LOGIC
RESET
R3
10.2k
1%
S1
1421 F18
BACKPLANE PC BOARD
Figure 18. 5V Only Application with Soft Reset
– 48V
– 48V
– 48V
BACKPLANE
R1
5k
1W
D1
5V
+ C2
2.2µF
25V
– 48V
+
2
24
C1
1µF
4
3
1
S1
Q1
IRFR9110
C3 +
2.2µF
25V
R2
15k
1/8W
23 22 21 20 19 18 17 16
10
9
13
14
LTC1421
8
11
15
6
7
R4
300Ω
1/8W
R3
56k
1/2W
Q2
MPSA06
R5
10k
1/2W
+
R6
400Ω
1/8W
1
+IN
3
+OUT
ASTRODYNE
+
ASD 10-48S5
2
5
–IN – OUT
CONTROL
6
C4
100µF
100V
12
5
1421 F19
5V
2A
C4
100µF
16V
PC BOARD
Figure 19. – 48V to 5V Hot Swappable Supply
17