LTC1647-1 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1647-1' PDF : 20 Pages View PDF
LTC1647-1/LTC1647-2/LTC1647-3
TYPICAL APPLICATIO
Hot Swapping Two Supplies
Two separate supplies can be independently controlled by
using the LTC1647-3. In some applications, sequencing
between the two power supplies is a requirement. For
example, it may be necessary to ramp-up one supply first
before allowing the second supply to power-up, as well as
requiring that this same supply ramp-down last on power-
down. Figure 14’s circuit illustrates how to program the
delays between the two pass transistors using the ON1
and ON2 pins (time events t1 to t4). t5 and t7 show both
channels being switched on simultaneously where se-
quencing is not crucial.
Some applications require that both channels be gated off
if a fault occurs in one channel. This is accomplished in
Figure 14 by using a crisscross FAULT-to-SENSE arrange-
ment of R3/R4 and R7/R8. t6 and t9 illustrate the circuit’s
operation.
5V SUPPLY
ON1
ON2
FAULT
GND
12V SUPPLY
R1
Q1
0.01Ω
IRF7413
+
VOUT1
(5A)
R3
CLOAD
100Ω R2
10Ω
VR1
R4
4.7k
1
15
13
R5 R6
10k 10k
VCC1 SENSE 1 GATE 1
2
ON1
3
FAULT 1
4
ON2
LTC1647-3
5
FAULT 2
8
GND
R7
VCC2 SENSE 2 GATE 2
12k
16
14
12
C1
10nF
VR10
VON1
t2
VON2
t1
VOUT1
R10
0.02Ω
R8
R9
C3
100Ω 10Ω
10nF
VOUT2
Q2
+
(2.5A)
IRF7413
CLOAD
VOUT2
Figure 14. Hot Swapping Two Supplies
t3
t4
t6
t9
t5
t7 t8
1647-1/2/3 F14
RELATED PARTS
PART NUMBER
LTC1421
LTC1422
LT1640L/LT1640H
LT1641
LT1642
LTC1643L/LTC1643H
LT1645
DESCRIPTION
2-Channel Hot Swap Controller
Hot Swap Controller in SO-8
Negative Voltage Hot Swap Controller in SO-8
High Voltage Hot Swap Controller in SO-8
Fault Protected Hot Swap Controller
PCI-Bus Hot Swap Controller
2-Channel Hot Swap Controller
20 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX:(408)434-0507 q www.linear-tech.com
COMMENTS
24-Pin, Operates from 3V to 12V and Supports –12V
System Reset Output with Programmable Delay
Operates from –10V to –80V
Operates from 9V to 80V
Operates Up to 16.5V, Protected to 33V
3.3V, 5V and ±12V in Narrow 16-Pin SSOP
Operates from 1.2V to 12V, Power Sequencing
1647f LT/TP 0100 4K • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 1999
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