LTC1643LIGN Linear Technology, LTC1643LIGN Datasheet - Page 14

• Manufacturer Part Number: LTC1643LIGN
• Description: IC CONTRLR HOTSWAP PCIBUS 16SSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC1643LIGN

• Applications: CompactPCI™
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS
LTC1643L/LTC1643L-1/LTC1643H
For the 12V supply, P-channel transistor Q4 is placed in
parallel with the internal switch. When the LTC1643H is
turned off, the GATE pin is held low and transistor Q3 is
turned on which pulls the gate of Q4 high, turning it off.
When the LTC1643H is turned on, the GATE pin goes high,
turning off Q3 and allowing R8 to pull the gate of Q4 low
to turn it on.
Because Q4 is in parallel with the internal 12V switch, the
load current will be shared in proportion to their respective
R
switch is 0.2 and the internal switch is 0.4 , then, at
1.5A load current, the external switch will provide 1A and
the internal switch 500mA. The circuit breaker current will
be reached when the internal current reaches 1A and the
external current is 2A or 3A load current.
14
DS(ON)
values. For example, if the R
CONTROLLER
SYSTEM
SYSTEM
SUPPLY
POWER
POWER
PCI
U
10k
10k
R3
R4
INFORMATION
U
8
2
5
6
7
ON
FAULT
PWRGD
12V
GND
V
EEIN
1
IN
W
Figure 8. Increasing 12V and – 12V Current Capability
3
3V
DS(ON)
1
IN
0.005
9
R2
3V
SENSE
of the external
2
4
10
IRF7413
GATE
U
Q2
11
R5
10
LTC1643H
3V
OUT
3
5V
3
IN
13
Q3
TP0610T
R8
100k
1
0.007
For the –12V supply, N-channel transistor Q6 is used to
provide the extra load current. When the LTC1643H is
turned on, the internal V
–12V output starts to pull down through D1 and turns on
Q5. When Q5 turns on, the gate of Q6 starts to rise, turning
it on. When the LTC1643H turns off, the V
pulled up to ground, diode D1 is reversed biased, and
transistor Q5 turns off, which allows resistor R10 to turn
off Q6.
The internal –12V switch provides the current limit for the
supply, but because the high R
(1.2 ) is in series with D1, very large currents can flow
through Q6 before the circuit breaker trips. However, if a
short to ground occurs on the –12V output, diode D1 will
prevent Q5 from turning on, which will prevent Q6 from
turning on.
R1
5V
2
Si9400
Q4
SENSE
4
12
10
C3
0.1 F
12V
V
TIMER
EEOUT
OUT
16
IRF7413
15
4
Q1
R6
10
C2
0.1 F
100
R7
EE
Q5
TP0610T
R9
200
R10
200
switch is turned on and the
DS(ON)
Si9410DY
1N4148
Q6
D1
of the internal switch
C1
0.047 F
12V
1.5A
5V
5A
3.3V
7.6A
GND
–12V
1.5A
EEOUT
1643 F08
pin is