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PDF LTC4214-1 Data sheet ( Hoja de datos )
| Número de pieza | LTC4214-1 | |
| Descripción | Negative Low Voltage Hot Swap Controllers | |
| Fabricantes | Linear Technology | |
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FEATURES
s Allows Safe Board Insertion and Removal from a
Live Backplane
s Controls Supplies from 0V to –16V
s Adjustable Analog Current Limit With Circuit
Breaker Timer
s Fast Response Time Limits Peak Fault Current
s Adjustable Soft-Start Current Limit
s Adjustable Timer with Drain Voltage Accelerated
Response
s Adjustable Undervoltage/Overvoltage Protection
s LTC4214-1: Latch Off After Fault
s LTC4214-2: Automatic Retry After Fault
s Available in the 10-Pin MSOP Package
U
APPLICATIO S
s Hot Board Insertion
s Electronic Circuit Breaker
s Negative Power Supply Control
s Central Office Switching
s High Availability Servers
s Disk Arrays
s Optical Networking/Switching
s ECL
LTC4214-1/LTC4214-2
Negative Low Voltage
Hot Swap Controllers
DESCRIPTIO
The LTC®4214 negative voltage Hot SwapTM controller
allows a board to be safely inserted and removed from a
live backplane. Output current is controlled by three stages
of current limiting: a timed circuit breaker, active current
limiting and a fast feedforward path that limits peak
current under worst-case catastrophic fault conditions.
Adjustable undervoltage and overvoltage detectors dis-
connect the load whenever the input supply exceeds the
desired operating range. The LTC4214 controls negative
supplies ranging from near zero to –16V. A multifunction
timer delays initial start-up and controls the circuit breaker’s
response time. This response time is accelerated by
sensing excessive MOSFET drain voltage, keeping the
MOSFET within its safe operating area (SOA). An adjust-
able soft-start circuit controls MOSFET inrush current at
start-up. A power good status output can enable a power
module at start-up or disable it if the circuit breaker trips.
The LTC4214-1 latches off after a circuit breaker fault times
out. The LTC4214-2 provides automatic retry after a fault.
The LTC4214 is available in the 10-pin MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
3.3V
GND
10Ω
100nF
GND
(SHORT PIN)
34k
1%
32.4k
1%
–5.2V
– 5.2V/5A ECL Supply Hot Swap Controller
2k
SMAJ7A
5.6nF
1nF PUSH
RESET
470Ω
1
VIN
LTC4214-1 2
PWRGD
9, 8 UV/OV
7
DRAIN
10 6
TIMER GATE
3
SS
4
SENSE
VEE
5
3.3nF
0.1µF
22Ω
EN
BSS138
CLOAD +
100µF
GND
–5.2V
ECL
75k
IRF7413
10Ω
10nF
0.01Ω
4214 TA01
GATE
5V/DIV
SENSE
20mV/DIV
VOUT
5V/DIV
PWRGD
5V/DIV
Start-Up Behavior
4214 TA02
421412f
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LTC4214-1/LTC4214-2
TYPICAL PERFOR A CE CHARACTERISTICS All voltages are referenced to VEE Unless
otherwise specified.
IGATE (Sourcing) vs Temperature
60
VIN = 12V
58 UV/OV = 2.5V
TIMER = 0V
56 VSENSE = VEE
54 VGATE = 0V
52
50
48
46
44
42
40
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G13
IGATE (ACL, Sinking)
vs Temperature
30
VIN = 12V
UV/OV = 2.5V
25 TIMER = 0V
VSENSE – VEE = 0.15V
20 VGATE = 3V
15
10
5
0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G14
IGATE (FCL, Sinking)
vs Temperature
400 VIN = 12V
350
UV/OV = 2.5V
TIMER = 0V
300
VSENSE – VEE = 0.3V
VGATE = 1V
250
200
150
100
50
0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G15
VGATE vs Temperature
12.0
VIN = 12V
11.8 UV/OV = 2.5V
TIMER = 0V
11.6 VSENSE = VEE
11.4
11.2
11.0
10.8
10.6
10.4
10.2
10.0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G16
VGATEH vs Temperature
3.6 VIN = 12V
3.4
UV/OV = 2.5V
VGATEH = VIN – VGATE
3.2
3.0
2.8
2.6
2.4
2.2
2.0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G17
VGATEL vs Temperature
0.8 VIN = 12V
0.7
UV/OV = 2.5V
TIMER = 0V
0.6
GATE THRESHOLD
BEFORE RAMP-UP
0.5
0.4
0.3
0.2
0.1
0
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G18
VUVHI vs Temperature
2.40
VIN = 12V
2.35
2.30
2.25
2.20
2.15
2.10
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G19
VUVHST vs Temperature
0.28
VIN = 12V
0.27
0.26
0.25
0.24
0.23
0.22
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G20
VOVHI vs Temperature
3.15
VIN = 12V
3.10
3.05
3.00
2.95
2.90
2.85
–55 –35 –15 5 25 45 65 85 105 125
TEMPERATURE (°C)
4214 G21
421412f
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OPERATIO
Hot Circuit Insertion
When circuit boards are inserted into a live backplane, the
supply bypass capacitors can draw huge transient cur-
rents from the power bus as they charge. The flow of
current damages the connector pins and glitches the
power bus, causing other boards in the system to reset.
The LTC4214 is designed to turn on a circuit board supply
in a controlled manner, allowing insertion or removal
without glitches or connector damage.
Initial Start-Up
The LTC4214 resides on a removable circuit board and
controls the path between the connector and the load with
an external MOSFET switch (see Figure 1). Both inrush
control and short-circuit protection are provided by the
MOSFET.
A detailed schematic is shown in Figure 2. – 12V and
GND receive power through the longest connector pins
and are the first to connect when the board is inserted. The
GATE pin holds the MOSFET off during this time. UV/OV
determines whether or not the MOSFET should be turned
on based upon internal high accuracy thresholds and an
external divider. UV/OV does double duty by also monitor-
ing whether or not the connector is seated. The top of the
divider detects GND by way of a short connector pin that
is the last to mate during the insertion sequence.
Interlock Conditions
A start-up sequence commences once these “interlock”
conditions are met.
1. The input voltage VIN exceeds 5.1V (UVLO).
2. The voltage at UV > 2.25V.
LONG
GND
LONG
–12V
BACKPLANE
PLUG-IN BOARD
LTC4214
+
CLOAD LOAD
4214 F01
Figure 1. Basic LTC4214 Hot Swap Topology
LTC4214-1/LTC4214-2
3. The voltage at OV < 2.85V.
4. The (SENSE – VEE) voltage is < 50mV (VCB).
5. The voltage at SS is < 0.2V (20 • VOS).
6. ThevoltageontheTIMERcapacitor(CT)is<1.7V(VTMRL).
7. The voltage at GATE is < 0.5V (VGATEL).
The first three conditions are continuously monitored and
the latter four are checked prior to initial timing or GATE
ramp-up. Upon exiting an OV condition, the TIMER pin
voltage requirement is inhibited. Details are described in
the Applications Information, Timing Waveforms section.
TIMER begins the start-up sequence by sourcing 5µA into
CT. If VIN, UV or OV falls out of range, the start-up cycle
stops and TIMER discharges CT to less than 1.7V, then
waits until the aforementioned conditions are once again
met. If CT successfully charges to 3V, TIMER pulls low
and both SS and GATE pins are released. GATE sources
50µA (IGATE), charging the MOSFET gate and associated
capacitance. The SS voltage ramp limits VSENSE to control
the inrush current. PWRGD pulls active low when GATE is
within 2.8V of VIN and DRAIN is lower than VDRNL.
Two modes of operation are possible during the time the
MOSFET is first turning on, depending on the values of
external components, MOSFET characteristics and nomi-
nal design current. One possibility is that the MOSFET will
LONG
GND
RX
10Ω
CX
100nF
SHORT R1
121k
1%
C1
1nF
R2
32.4k
LONG 1%
–12V
Z1: SMAJ15A
Z1
CIN
0.1µF
RIN
470Ω
R3
10k
8
OV
9 UV
1
VIN PWRGD 2
10 LTC4214-1
TIMER
3
SS
7
DRAIN
CLOAD +
100µF
TYP
R4
10k
VEE SENSE GATE
CSS
22nF
CT
47nF
54
6
CC
10nF
RC 10Ω
RD
475k
RS
0.025Ω
Q1
IRF7413
4214 F02
GND
EN
VOUT
Figure 2. –12V, 2A Hot Swap Controller
421412f
11
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| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC4214-1.PDF ] | |
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