LTC1643L/LTC1643L-1/LTC1643H
PCI-Bus Hot Swap
Controller
FEATURES
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DESCRIPTIO
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Allows Safe Board Insertion and Removal from a
Live PCI Slot
Works on either a Motherboard (LTC1643H) or
CompactPCI
TM
Card (LTC1643L/LTC1643L-1)
Controls –12V, 3.3V, 5V, 12V Supplies
Programmable Foldback Current Limit with
Circuit Breaker
User-Programmable Supply Voltage Power-Up Rate
High Side Drive for External N-Channels
–12V and 12V On-Chip Switches
Fault and Power-Good Outputs
APPLICATIO S
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PCI-Based Servers
CompactPCI Compliant Boards
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
CompactPCI is a trademark of PCI Industrial Computer Manufacturing Group.
The LTC
®
1643 is a Hot Swap
TM
controller that allows a board
to be safely inserted and removed from a live PCI-Bus slot.
Two external N-channel transistors control the 3.3V and 5V
supplies while on-chip switches control the –12V and 12V
supplies. All supply voltages can be ramped up at a program-
mable rate. An electronic circuit breaker protects all four
supplies against overcurrent faults. The foldback current limit
feature limits current spikes and power dissipation when
shorts occur and allows boards with large capacitances to be
powered up without tripping the circuit breaker. The PWRGD
output indicates when all of the supply voltages are within
tolerance and the FAULT output indicates an overcurrent
condition. The ON(LTC1643H)/ON (LTC1643L/LTC1643L-1)
pin is used to cycle the board power or reset the circuit
breaker. The LTC1643L-1 has the
±12V
power good com-
parators disabled.
The LTC1643 is available in a 16-pin narrow SSOP package.
TYPICAL APPLICATION
Hot Swappable PCI Supply
R1
0.007Ω
Q1
IRF7413
R2
0.005Ω
Q2
IRF7413
R6
10Ω
SYSTEM
POWER
SUPPLY
9
3V
IN
GND
1
12V
IN
2
V
EEIN
5
ON
8
PCI
POWER
SYSTEM
CONTROLLER
RESET
R3
10k
R4
10k
6
10
R5
10Ω
11
3
13
12
5V
SENSE
14
5V
OUT
R7
100Ω
C1
0.047µF
3V
SENSE
GATE
3V
OUT
5V
IN
12V
OUT
LTC1643H
V
EEOUT
FAULT
TIMER
7
PWRGD
U
5V
5A
3.3V
7.6A
GND
16
15
4
C2
0.1µF
12V
500mA
–12V
100mA
LOGIC
RESET
1643 TA01
U
U
1
LINER [ LINEAR TECHNOLOGY ]
