Datasheet

17
LTC1421/LTC1421-2.5
APPLICATIONS INFORMATION
WUU
U
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
Figure 19. –48V to 5V Hot Swappable Supply
10
7
14
13
8
15
1
LTC1421
16
Q1
MTB50N06E
C1
1µF
C2
1µF
R2
28k
1%
5V
171819202122
5963
S1
11
12
23
1421 F18
5V
5V
5V
POWERGOOD
FAULT
SOFT RESET
HARD RESET
R1
0.005Ω
1W
R3
10.2k
1%
RESET
LOGIC
C
LOAD
10k
10k
1/6
LS7004
PC BOARDBACKPLANE
1µF
43
21
R4
10k
Figure 18. 5V Only Application with Soft Reset
10
9
13
14
8
11
15
6
7
2
24
4
3
1
16
R4
300Ω
1/8W
R3
56k
1/2W
Q2
MPSA06
Q1
IRFR9110
C1
1µF
–48V
171819202122
512
23
STAGGERED CONNECTOR
C2
2.2µF
25V
R1
5.1k
1W
D1
5.1V
+
C3
2.2µF
25V
+
2
1
5
6
3
C4
100µF
16V
5V
2A
+
C4
100µF
100V
+
1421 F19
PC BOARDBACKPLANE
–48V
S1
–48V
–48V
R5
10k
1/2W
R6
402Ω
1/8W
R2
15k
1/8W
ASTRODYNE
ASD 10-48S5
CONTROL
+IN +OUT
–IN –OUT
LTC1421
1µF