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PDF LTC1644 Data sheet ( Hoja de datos )
| Número de pieza | LTC1644 | |
| Descripción | CompactPCI Bus Hot Swap Controller | |
| Fabricantes | Linear | |
| Logotipo |  |
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FEATURES
s Allows Safe Board Insertion and Removal from a
Live, CompactPCITM Bus
s Controls –12V, 3.3V, 5V and 12V Supplies
s Adjustable Foldback Current Limit with Circuit
Breaker
s Dual-Level Circuit Breakers Protect 5V and 3.3V
Supplies from Overcurrent and Short-Circuit Faults
s LOCAL_PCI_RST# Logic On-Chip
s PRECHARGE Output Biases I/O Pins During Card
Insertion and Extraction
s Adjustable Supply Voltage Power-Up Rate
U
APPLICATIO S
s Hot Board Insertion into CompactPCI Bus
LTC1644
CompactPCI Bus
Hot Swap Controller
DESCRIPTIO
The LTC®1644 is a Hot SwapTM controller that allows a board
to be safely inserted and removed from a CompactPCI bus
slot. External N-channel transistors control the 3.3V/5V
supplies, while on-chip switches control the
–12V and 12V supplies. The 3.3V and 5V supplies can be
ramped up at a programmable rate. Electronic circuit break-
ers protect all four supplies against overcurrent faults. The
PWRGD output indicates when all of the supply voltages are
within tolerance. The OFF/ON pin is used to cycle the board
power or reset the circuit breaker. The PRECHARGE output
can be used to bias the bus I/O pins during card insertion
and extraction. PCI_RST# is combined on-chip with
HEALTHY# in order to generate LOCAL_PCI_RST#.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
CompactPCI is a trademark of the PCI Industrial Computer Manufacturers Group.
TYPICAL APPLICATIO
5V
LONG 5V
3.3V
LONG 3.3V
12V
–12V
BD_SEL#
HEALTHY#
PCI_RST#
GROUND
I/O PIN 1
I/O PIN 128
PCB EDGE
BACKPLANE BACKPLANE
CONNECTOR CONNECTOR
C8
0.1µF
PER 10
POWER
PINS
C9
0.1µF
PER 10
POWER
PINS
R22 2.74Ω
C6
0.01µF
R21 1.74Ω
C7
0.01µF
3VIN*
Z3
5VIN*
R1
0.005Ω
Q1
IRF7413
Z4
17
R3
10Ω
16 15 18
R2
0.007Ω
Q2
IRF7413
+
CLOAD(5VOUT)
+
C1 CLOAD(3VOUT)
R4
10Ω
R5 0.047µF
1k
13 14
3
5VOUT
5V AT 5.7A
3VOUT
3.3V AT 8A
Z1 Z2
5VIN
EARLY V(I/O)
R17
2k
R20 1.2k
3VIN
1
12VIN
2
VEEIN
R19
1k 5
OFF/ON
6
FAULT
R18
2k 7
PWRGD
9
RESETIN
3VSENSE GATE 3VOUT 5VIN
LTC1644
20-PIN SSOP
5VSENSE
5VOUT
20
12VOUT
+
CLOAD(12VOUT)
19
VEEOUT
CLOAD(VEEOUT)
12VOUT
12V AT 500mA
VEEOUT
–12V AT 100mA
4
TIMER
10
RESETOUT
C2
0.1µF
R6
2k
3VOUT
R15
1Ω
C4
0.01µF
R16
1Ω
C5
0.01µF
I/O DATA LINE 1
R13 10Ω
GND PRECHARGE
8 12
R10
18Ω 5%
R11
51k
C3 4.7nF
DRIVE
11
R9
24Ω
R8 1k
R12
51k
1V
±10%
Q3 R7
MMBT2222A 12Ω
I/O DATA LINE 128
R14 10Ω
Z1, Z2: SMAJ12CA Z3, Z4: 1PMT5.0AT3 *5VIN AND 3VIN MAY BE USED AS SOURCES OF EARLY POWER
3VIN
RESET#
I/O #1
I/O #128
1644 F01
PCI
BRIDGE
CHIP
Figure 1
1644f
1
1 page  
LTC1644
TYPICAL PERFOR A CE CHARACTERISTICS
5V/3.3V Circuit Breaker Trip
Voltage vs Temperature
56.2
TIMER PIN FLOATING
56.0
55.8
55.6
55.4
55.2
55.0
54.8
–50 –25
0
25 50 75 100
TEMPERATURE (°C)
1644 G10
GATE Pin Current vs Temperature
(VGATE = 2V, FAULT = 0V)
16
VGATE = 2V
14 FAULT = 0V
12
10
8
6
4
2
0
–50 –25 0
25 50 75 100
TEMPERATURE (°C)
1644 G13
GATE Pin Voltage vs Temperature
11.97
IGATE = –1µA
11.96
11.95
11.94
11.93
11.92
–50 –25
0
25 50 75
TEMPERATURE (°C)
100
1644 G16
5V/3.3V Circuit Breaker Overcurrent
Fault Response Time
vs Temperature
48.0
47.5
47.0
46.5
46.0
45.5
45.0
44.5
–50 –25
0
25 50 75
TEMPERATURE (°C)
100
1644 G11
GATE Pin Current vs Temperature
(VGATE = 5V, OFF/ON = 4V)
300
VGATE = 5V
OFF/ON = 4V
250
200
150
100
50
0
–50 –25
0
25 50 75
TEMPERATURE (°C)
100
1644 G14
12V Internal Switch Voltage Drop
vs Temperature
0.35
I = 500mA
0.30
0.25
0.20
0.15
0.10
0.05
0
–50 –25
0
25 50 75
TEMPERATURE (°C)
100
1644 G17
5V/3.3V Circuit Breaker Short-
Circuit Response Time
vs Temperature
0.125
0.120
0.115
0.110
0.105
0.100
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
1644 G12
GATE Pin Current vs Temperature
(VGATE = 0V, OFF/ON = 0V)
–40
VGATE = 5V
–45 OFF/ON = 4V
–50
–55
–60
–65
–70
–75
–80
–85
–50
–25 0 25 50
TEMPERATURE (°C)
75 100
1644 G15
VEE Internal Switch Voltage Drop
vs Temperature
0.18
IEE = 100mA
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
–50
–25 0 25 50
TEMPERATURE (°C)
75 100
1644 G18
1644f
5
5 Page 
TI I G DIAGRA S
tOC Overcurrent Fault Detect
V5VSENSE OR
V3VSENSE
5V OR 3.3V
100mV
FAULT
FALL TIME ≤ 1µs
5VIN = 5V, 3VIN = 3.3V
tOC
1644 TD01
LTC1644
tSC Short-Circuit Fault Detect
V5VSENSE OR
V3VSENSE
5V OR 3.3V
200mV
FAULT
FALL TIME ≤ 10ns
5VIN = 5V, 3VIN = 3.3V
tSC
1644 TD02
APPLICATIO S I FOR ATIO
Hot Circuit Insertion
When a circuit board is inserted into a live CompactPCI
(CPCI) slot, the supply bypass capacitors on the board can
draw huge supply transient currents from the CPCI power
bus as they charge up. The transient currents can cause
glitches on the power bus, causing other boards in the
system to reset.
The LTC1644 is designed to turn a board’s supply voltages
on and off in a controlled manner, allowing the board to be
safely inserted or removed from a live CPCI slot without
glitching the system power supplies. The chip also protects
the supplies from shorts, precharges the bus I/O pins during
insertion and extraction and monitors the supply voltages.
The LTC1644 is specifically designed for CPCI applica-
tions where the chip resides on the plug-in board.
LTC1644 Feature Summary
• Allows safe board insertion and removal from a CPCI
backplane.
• Controls all four CPCI supplies: –12V, 12V, 3.3V and 5V.
• Adjustable foldback current limit: an adjustable analog
current limit with a value that depends on the output
voltage. If the output is shorted to ground, the current
limit drops to keep power dissipation and supply glitches
to a minimum.
• 12V and –12V circuit breakers: if either supply remains
in current limit too long, the circuit breaker will trip, the
supplies are turned off and the FAULT pin is pulled low.
• Dual-level, adjustable 5V and 3.3V circuit breakers: if
either supply exceeds current limit for too long, the
circuit breaker will trip, the supplies will be turned off
and the FAULT pin will be asserted. In the event that
either supply exceeds 3 times the nominal current level,
all supplies will be turned off and the FAULT pin will be
asserted immediately.
• Current limit during power up: the supplies are allowed
to power up in current limit. This allows the chip to
power up boards with widely varying capacitive loads
without tripping the circuit breaker. The maximum
allowable power-up time is adjustable using the TIMER
pin.
• 12V and –12V power switches on chip.
• PWRGD output: monitors the voltage status of the four
supply voltages.
• PCI_RST# combined on-chip with HEALTHY# to create
LOCAL_PCI_RST# output. If HEALTHY# deasserts,
LOCAL_PCI_RST# is asserted independent of
PCI_RST#.
• Precharge output: on-chip reference and amplifier pro-
vide 1V for biasing bus I/O connector pins during CPCI
card insertion and extraction.
• Space saving 20-pin SSOP package.
CPCI Power Requirements
CPCI systems usually require four power rails: 5V, 3.3V,
12V and –12V. The tolerance of the supplies as measured
at the components on the plug-in card is summarized in
Table 1.
Table 1. Compact PCI Power Specifications
SUPPLY
5V
TOLERANCE
+ 5%/– 3%
MAX RIPPLE (P-P)
50mV
3.3V +5%/–3%
50mV
12V ±5%
240mV
– 12V
±5%
240mV
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11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC1644.PDF ] | |
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