LTC1643AL-1CGN#PBF [Linear]
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| 型号： | LTC1643AL-1CGN#PBF |
| 厂家： | 
Linear |
| 描述： | 暂无描述 光电二极管 |
| 文件： | 总16页 (文件大小：236K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1643AL
LTC1643AL-1/LTC1643AH
PCI-Bus Hot Swap
Controller
U
FEATURES
DESCRIPTIO
TheLTC®1643AisaHotSwapTM controllerthatallowsaboard
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. Allsupplyvoltagescanberampedupataprogram-
mable rate. An electronic circuit breaker protects all four
suppliesagainstovercurrentfaults.Thefoldbackcurrentlimit
feature limits current spikes and power dissipation when
shortsoccurandallowsboardswithlargecapacitancestobe
poweredupwithouttrippingthecircuitbreaker. ThePWRGD
output indicates when all of the supply voltages are within
tolerance and the FAULT output indicates an overcurrent
condition. The ON(LTC1643AH)/ON (LTC1643AL/
LTC1643AL-1) pin is used to cycle the board power or reset
the circuit breaker. The LTC1643AL-1 has the ±12V power
good comparators disabled.
■
Allows Safe Board Insertion and Removal from a
Live PCI Slot
■
Works on either a Motherboard (LTC1643AH) or
CompactPCITM Card (LTC1643AL/LTC1643AL-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-Channel MOSFETs
■
–12V and 12V On-Chip Switches
Fault and Power-Good Outputs
■
■
Available in a Narrow 16-Lead SSOP Package
U
APPLICATIO S
■
PCI-Based Servers
CompactPCICompliant Boards
■
TheLTC1643Aisavailableina16-pinnarrowSSOPpackage.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Hot Swap is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
U
TYPICAL APPLICATION
Hot Swappable PCI Supply
R1
0.007Ω
Q1
IRF7413
5V
5A
R6
10Ω
R2
0.005Ω
Q2
IRF7413
3.3V
7.6A
GND
SYSTEM
POWER
SUPPLY
R5
10Ω
R7
100Ω
C1
0.047µF
9
10
11
3
13
12
14
3V
IN
3V
GATE 3V
5V
IN
5V
5V
OUT
SENSE
OUT
SENSE
8
GND
1
2
12V
IN
V
EEIN
16
5
6
7
12V
12V
OUT
ON
500mA
LTC1643AH
R3
15
4
–12V
100mA
V
EEOUT
10k
PCI
FAULT
POWER
SYSTEM
CONTROLLER
TIMER
R4
10k
C2
0.1µF
PWRGD
LOGIC
RESET
RESET
1643A TA01
1643afb
1
LTC1643AL
LTC1643AL-1/LTC1643AH
W W U W
U
W U
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
ORDER PART NUMBER
Supply Voltages
TOP VIEW
12VIN ................................................................ 13.2V
LTC1643AHCGN
V
EEIN .............................................................. –13.2V
12V
1
2
3
4
5
6
7
8
16 12V
LTC1643ALCGN
LTC1643AL-1CGN
LTC1643AHIGN
LTC1643ALIGN
LTC1643AL-1IGN
IN
OUT
V
EEIN
15
14
13
12
11
10
9
V
Input Voltage (Pin 5) ................ –0.3V to (12VIN + 0.3V)
Output Voltages (Pins 6, 7) ...... –0.3V to (12VIN + 0.3V)
Analog Voltages
EEOUT
3V
OUT
5V
5V
5V
OUT
TIMER
ON/ON*
FAULT
PWRGD
GND
IN
SENSE
(Pins 3, 4, 9, 10 to 14) ........ –0.3V to (12VIN + 0.3V)
VEEOUT ............................................ –13.2V to + 0.3V
12VOUT .............................................. –0.3V to 13.2V
Operating Temperature Range
GATE
GN PART MARKING
3V
SENSE
IN
1643AH
1643AL
643AL1
643AHI
643ALI
43AL1I
3V
GN PACKAGE
16-LEAD NARROW PLASTIC SSOP
*ON FOR LTC1643AH,
ON FOR LTC1643AL/LTC1643AL-1
LTC1643ALC/LTC1643AL-1C/
LTC1643AHC ........................................... 0°C to 70°C
LTC1643ALI/LTC1643AL-1I/
TJMAX = 150°C, θJA = 135°C/ W
LTC1643AHI ...................................... –40°C to 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPB
Lead Free Part Marking: http://www.linear.com/leadfree/
ConsultLTCMarketingforpartsspecifiedwithwideroperatingtemperatureranges.
The
12VIN
●
denotes specifications which apply over the full operating
DCELECTRICALCHARACTERISTICS
temperature range, otherwise specifications are T = 25°C. V
= 12V, V
= –12V, V
= 3.3V, V
= 5V (Note 2)
EEIN
3VIN
5VIN
A
SYMBOL PARAMETER
Supply Current
CONDITIONS
MIN
TYP
MAX
UNITS
I
V
ON = GND, ON = 3V
●
3.5
8
mA
DD
12VIN
V
Undervoltage Lockout
12V
IN
IN
●
●
●
7
2.25
2.25
9.5
2.5
2.5
10.8
2.75
2.75
V
V
V
LKO
IN
3V
5V
V
Foldback Current Limit Voltage
V
V
V
V
= (V
– V
– V
– V
– V
), V
), V
), V
), V
= 0V
> 4V
= 0V
> 2V
●
●
●
●
4
40
4
7.5
53
7.5
53
12
65
12
65
mV
mV
mV
mV
FB
FB
FB
FB
FB
5VIN
5VIN
3VIN
3VIN
5VSENSE
5VSENSE
3VSENSE
3VSENSE
5VOUT
5VOUT
3VOUT
3VOUT
= (V
= (V
= (V
40
t
I
Circuit Breaker Trip Filter Time
GATE Pin Output Current
14.6
µs
CB
CP
Charge Pump On, V
Charge Pump Off, V
Charge Pump Off, V
= GND, FAULT = High
= 5V, FAULT = High
= 2V, FAULT = Low
●
●
–20
3
–62
200
17.5
–100
µA
µA
mA
GATE
GATE
GATE
∆V
External Gate Voltage
(V
(V
– V
)
GATE
100
200
mV
GATE
12VIN
V
Internal Switch Voltage Drop
– V
),
0°C ≤ T ≤ 70°C
●
●
225
225
600
750
DROP
12VIN
12VOUT
A
I
= 500mA
–40°C ≤ T ≤ 85°C
mV
mV
12VOUT
A
(V
EEOUT
– V
), I = 100mA
EEIN VEEIN
●
125
250
I
Current Foldback
12V = 12V, 12V
= 0V
●
●
●
●
50
525
50
250
850
160
450
600
1500
500
mA
mA
mA
mA
CL
IN
OUT
OUT
12V = 12V, 12V
= 10V
IN
EEIN
EEIN
V
V
= –12V, V
= –12V, V
= 0V (LTC1643AL/LTC1643AH Only)
= –10V
EEOUT
EEOUT
225
800
T
Thermal Shutdown Temperature
Power-Good Threshold Voltage
150
°C
TS
V
V
0°C ≤ T ≤ 70°C
●
●
10.8
10.4
11.1
11.1
11.4
11.4
V
V
TH
12VOUT
A
LTC1643AH/LTC1643AL Only
–40°C ≤ T ≤ 85°C
A
V
0°C ≤ T ≤ 70°C
●
●
–10.2
–10.0
–10.5
–10.5
–10.8
–10.8
V
V
EEOUT
A
LTC1643AH/LTC1643AL Only
–40°C ≤ T ≤ 85°C
A
1643afb
2
LTC1643AL
LTC1643AL-1/LTC1643AH
DC ELECTRICAL CHARACTERISTICS
The
12VIN
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25°C.
A
V
= 12V, V
= –12V, V
= 3.3V, V
= 5V (Note 2)
EEIN
3VIN
5VIN
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Power-Good Threshold Voltage
V
V
0°C ≤ T ≤ 70°C
●
●
2.8
2.75
2.9
2.9
3.0
3.0
V
V
TH
3VOUT
5VOUT
A
–40°C ≤ T ≤ 85°C
A
0°C ≤ T ≤ 70°C
●
●
4.5
4.4
4.65
4.65
4.75
4.75
V
V
A
–40°C ≤ T ≤ 85°C
A
V
Input Low Voltage
ON/ON, FAULT
●
●
●
0.8
V
V
V
IL
V
V
I
Input High Voltage
Output Low Voltage
ON/ON Pin Input Current
ON/ON, FAULT
2
IH
FAULT, PWRGD, I = 3mA
ON/ON = GND
0.4
OL
IN
●
●
± 0.08
± 0.08
±10
±10
µA
µA
ON/ON= 12V
IN
5V
3V
Input Current
Input Current
5V
3V
= 5V
●
●
●
●
●
●
50
50
100
100
700
600
500
500
µA
µA
µA
µA
µA
µA
SENSE
SENSE
SENSE
= 3V
SENSE
5V Input Current
IN
5V = 5V
IN
460
320
240
220
3V Input Current
IN
3V = 3V
IN
5V
OUT
3V
OUT
Input Current
Input Current
5V
OUT
3V
OUT
= 5V, ON = 3V, ON = GND
= 3.3V, ON = 3V, ON = GND
R
DIS
5V
3V
12V
Discharge Impedance
Discharge Impedance
ON = GND or ON = 3V
ON = GND or ON = 3V
ON = GND or ON = 3V
ON = GND or ON = 3V
100
70
450
1600
Ω
Ω
Ω
Ω
OUT
OUT
Discharge Impedance
Discharge Impedance
OUT
V
EEOUT
I
TIMER Pin Current
Timer On, V
Timer Off, V
= GND
= 5V
●
●
–15
0.5
–22
45
–27
1.3
µA
TIMER
TIMER
TIMER
mA
V
TIMER Threshold Voltage
(V
12VIN
– V )
TIMER
0.9
V
TIMER
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
U W
TYPICAL PERFORMANCE CHARACTERISTICS
3.3V and 5V Current
Foldback Profile
12V Current Foldback Profile
–12V Current Foldback Profile
11
10
9
1.0
0.5
0
1.0
0.5
0
3V
OUT
8
7
5V
OUT
6
5
4
3
2
1
R
3
= 0.005Ω
SENSE
0
0
2
4
6
8
10
12
0
–2
–4
–6
–8
–10
–12
0
1
2
4
5
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1643A G02
1643A G03
1643A G01
1643afb
3
LTC1643AL
LTC1643AL-1/LTC1643AH
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Timer Current vs Temperature
Gate I
vs Temperature
Gate Current vs Temperature
SINK
90
80
70
60
50
40
23.5
23.0
22.5
22.0
21.5
21.0
20.5
20.0
19.5
25.0
22.5
20.0
17.5
15.0
12.5
10.0
FAULT = LOW
–50 –25
0
25
50
75 100 125
–25
0
25
50
75
125
50
TEMPERATURE (°C)
100 125
–50
100
–50
25
75
–25
0
TEMPERATURE (°C)
TEMPERATURE (°C)
1643A G06
1643A G04
1643A G05
Power Good Threshold Voltage vs
Power Good Threshold Voltage vs
Power Good Threshold Voltage vs
Temperature (3V
Temperature (5V
)
)
OUT
Temperature (12V
)
OUT
OUT
11.14
11.12
11.10
11.08
11.06
11.04
4.68
4.67
4.66
4.65
4.64
4.63
4.62
2.904
2.903
2.902
2.901
2.900
2.899
2.898
2.897
2.896
–50
0
25
50
75 100 125
–25
50
100 125
–25
0
25
50
75
125
–50 –25
0
25
75
–50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1643A G07
1643A G08
1643A G09
Power Good Threshold Voltage
vs Temperature (V
12V Internal Switch Voltage Drop
vs Temperature
V
Internal Switch Voltage Drop
EE
)
vs Temperature
EEOUT
180
160
140
120
100
80
–10.58
–10.56
–10.54
–10.52
–10.50
–10.48
–10.46
–10.44
–10.42
325
300
275
250
225
200
175
150
I
= 100mA
I
= 500mA
VEEIN
12VOUT
60
50
0
TEMPERATURE (°C)
100 125
–25
0
25
50
75
125
–50 –25
25
75
–50
100
50
0
TEMPERATURE (°C)
100 125
–50 –25
25
75
TEMPERATURE (°C)
1643A G12
1643A G10
LT1643A G11
1643afb
4
LTC1643AL
LTC1643AL-1/LTC1643AH
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Timer Threshold Voltage
vs Temperature
Circuit Breaker Trip Filter Time
vs Temperature
12V Supply Current
IN
vs Temperature
3.72
3.70
3.68
3.66
3.64
3.62
15.50
15.25
15.00
14.75
14.50
14.25
14.00
1.0
0.9
0.8
0.7
V
– V
TIMER
12VIN
–50
–25
0
25
50
75 100 125
50
TEMPERATURE (°C)
100 125
–50
25
TEMPERATURE (°C)
50
75
100 125
–50 –25
0
25
75
–25
0
TEMPERATURE (°C)
1643A G15
1643A G13
1643A G14
5V Supply Current
V
Supply Current
3V Supply Current
IN
EEIN
IN
vs Temperature
vs Temperature
vs Temperature
270
268
266
264
262
260
258
256
0.90
0.89
0.88
0.87
0.86
0.85
0.84
275.0
272.5
270.0
267.5
265.0
262.5
260.0
50
TEMPERATURE (°C)
100 125
50
TEMPERATURE (°C)
100 125
50
100 125
–50 –25
0
25
75
–50 –25
0
25
75
–50 –25
0
25
75
TEMPERATURE (°C)
LT1643A G17
1643A G16
1643A G18
12V Undervoltage Lockout
5V Undervoltage Lockout
IN
IN
V
OL
vs Temperature
vs Temperature
vs Temperature
350
300
250
200
150
100
50
9.515
9.510
9.505
9.500
9.495
9.490
9.485
2.454
2.452
2.450
2.448
2.446
2.444
2.442
I = 3mA
FAULT
PWRGD
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
50
TEMPERATURE (°C)
100 125
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–50 –25
0
25
75
1643A G19
1643A G20
1643A G21
1643afb
5
LTC1643AL
LTC1643AL-1/LTC1643AH
U W
TYPICAL PERFORMANCE CHARACTERISTICS
3V Foldback Current Limit
3V Undervoltage Lockout
5V Foldback Current Limit
IN
IN
IN
Voltage vs Temperature
vs Temperature
Voltage vs Temperature
70
60
50
40
30
20
10
0
2.454
2.452
2.450
2.448
2.446
2.444
2.442
70
60
50
40
30
20
10
0
3V
OUT
= 3.3V
5V
= 5V
OUT
5V
= 0V
3V
OUT
= 0V
OUT
50
100 125
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
–50 –25
0
25
75
50
100 125
–50 –25
0
25
75
TEMPERATURE (°C)
TEMPERATURE (°C)
1643A G23
1643A G21
1643A G24
V
Current Foldback
12V Current Foldback
vs Temperature
EE
vs Temperature
V
OL
vs I
(25°C)
SINK
600
500
400
300
200
100
0
1200
1000
800
600
400
200
0
800
700
600
500
400
300
200
100
0
12V
OUT
= 12V
FAULT
V
= –12V
EEOUT
PWRGD
V
= 0V
50
EEOUT
25
12V
= 0V
OUT
2
4
I
8
0
10
100
50
100
6
–50 –25
0
75
–50 –25
0
25
75
(mA)
TEMPERATURE (°C)
TEMPERATURE (°C)
SINK
1643A G27
1643A G25
1643A G26
U
U
U
PIN FUNCTIONS
12VIN (Pin 1): 12V Supply Input. It powers all the chip’s
internal circuitry. A 0.5Ω switch is connected between
12VIN and 12VOUT with a foldback current limit. An under-
voltage lockout circuit prevents the switches from turning
on while the 12VIN pin voltage is less than 9.5V typically.
TIMER (Pin 4): Analog Current Fault Inhibit Timing Input.
Connect a capacitor from TIMER to GND. With the chip
turned off (ON = GND or ON = High) or the internal circuit
breakertripped(FAULT=GND),theTIMERpinisinternally
held at GND. When the chip is turned on, a 22µA pull-up
current source is connected to TIMER. Current limit faults
will be ignored until the voltage at the TIMER pin rises to
within 0.9V of 12VIN.
VEEIN (Pin 2): –12V Supply Input. A 1.2Ω switch is
connected between VEEIN and VEEOUT with a foldback
current limit.
ON/ON(Pin5):DigitalInput.TheLTC1643AL/LTC1643AL-1
have an active low enable, ON, and the LTC1643AH has an
active high enable, ON. When the ON pin is pulled high or
1643afb
3VOUT (Pin 3): Analog Input. Used to monitor the 3.3V
output supply voltage. The PWRGD signal cannot go low
until the 3VOUT pin exceeds 2.9V typically.
6
LTC1643AL
LTC1643AL-1/LTC1643AH
U
U
U
PIN FUNCTIONS
the ON pin pulled low, the GATE pin is pulled high by a
62µA current source and the internal 12V and –12V
switches are turned on. When the ON pin is pulled low or
the ON pin pulled high, the GATE pin will be pulled to
ground by a 200µA current source and the 12V and –12V
switches turned off.
3VSENSE (Pin 10): The 3.3V Current Limit Set Pin. With a
sense resistor placed in the supply path between 3VIN and
3VSENSE, the GATE pin voltage will be adjusted to maintain
a constant voltage across the sense resistor and a con-
stantcurrentthroughtheswitch.Afoldbackfeaturemakes
the current limit decrease as the voltage at the 3VOUT pin
approaches GND. To disable the current limit, 3VSENSE
and 3VIN can be shorted together.
The ON/ON pin is also used to reset the electronic circuit
breaker. If the ON/ON pin is cycled following the trip of the
circuit breaker, the circuit breaker is reset and a normal
power-up sequence will occur.
GATE (Pin 11): High Side Gate Drive for the External
N-Channel Pass Transistors. Requires an external series
RC network for the current limit loop compensation and
setting the minimum ramp-up rate. During power-up, the
slope of the voltage rise at the GATE is set by the 62µA
current source connected to 12VIN and the external ca-
pacitorconnectedtoGNDorbythe3.3Vor5Vcurrentlimit
and the bulk capacitance on the 3VOUT or 5VOUT suppy
lines. During power-down, the slope of the falling voltage
is set by the 200µA current source connected to GND and
the external GATE capacitor.
FAULT(Pin6):Open-DrainDigitalI/O.FAULTispulledlow
when a current limit fault is detected. Current limit faults
are ignored while the voltage at the TIMER pin is less than
12VIN – 0.9V. Once the TIMER cycle is complete, FAULT
will pull low typically 14.6µs after any of the supplies go
into current limit. At the same time, the GATE and TIMER
pins are pulled to GND and the 12V and –12V switches are
turnedoff. Thechipwillremainlatchedintheoffstateuntil
the ON/ON pin is toggled or the power is cycled.
The voltage at the GATE pin will be modulated to maintain
a constant current when either the 3V or 5V supplies go
into current limit. When a current limit fault occurs after
the inhibit period set by the TIMER pin capacitance, the
undervoltage lockout circuit on 3.3V, 5V or 12V trips or
the FAULT pin is pulled low, the GATE pin is immediately
pulled to GND.
Forcing the FAULT pin low with an external pull-down will
immediately turn off the internal switches and force the
GATE and TIMER pins to GND independent of the state of
theON/ONpin. However, thechipisnotlatchedintotheoff
state, so when the FAULT pin is released, the state of the
chip will be determined by the ON pin.
PWRGD (Pin 7): Open-Drain Digital Power-Good Output.
PWRGD remains low while V12VOUT ≥ 11.4V, V3VOUT ≥ 3V,
V5VOUT ≥ 4.75V and VEEOUT ≤ –10.8V. The LTC1643AL-1
hasthepowergoodcomparatorsconnectedtothe12VOUT
and VEEOUT pins disabled, with only the 3VOUT and 5VOUT
outputs being monitored to generate PWRGD. When one
of the supplies falls below its power-good threshold
voltage, PWRGDwillgohighaftera15µsdeglitchingtime.
The switches will not be turned off when PWRGD goes
high.
5VSENSE (Pin 12): 5V Current Limit Set Pin. With a sense
resistor placed in the supply path between 5VIN and
5VSENSE, the GATE pin voltage will be adjusted to maintain
a constant voltage across the sense resistor and a con-
stantcurrentthroughtheswitch.Afoldbackfeaturemakes
the current limit decrease as the voltage at the 5VOUT pin
approaches GND. To disable the current limit, 5VSENSE
and 5VIN can be shorted together.
5VIN (Pin 13): Analog Input. Used to monitor the 5V input
supply voltage. An undervoltage lockout circuit prevents
the switches from turning on when the voltage at the 5VIN
pin is less than 2.5V typically.
GND (Pin 8): Chip Ground.
3VIN (Pin 9): 3.3V Supply Sense Input. An undervoltage
lockout circuit prevents the switches from turning on
when the voltage at the 3VIN pin is less than 2.5V typically.
If no 3.3V input supply is available, tie 3VIN to the 5VIN pin.
5VOUT (Pin 14): Analog Input. Used to monitor the 5V
output supply voltage. The PWRGD signal cannot go low
until the 5VOUT pin exceeds 4.65V typically.
1643afb
7
LTC1643AL
LTC1643AL-1/LTC1643AH
U
U
U
PIN FUNCTIONS
V
EEOUT (Pin 15): –12V Supply Output. A 1.2Ω switch is
12VOUT (Pin 16): 12V Supply Output. A 0.5Ω switch is
connected between 12VIN and 12VOUT. 12VOUT must
exceed11.4VbeforethePWRGDsignalcangohighonthe
LTC1643AH and LTC1643AL.
connected between VEEIN and VEEOUT. VEEOUT must
exceed –10.8V before the PWRGD signal can go high on
the LTC1643AH and LTC1643AL.
W
BLOCK DIAGRAM
5V
IN
5V
3V
3V
IN
3V
OUT
3
5V
OUT
14
SENSE
GATE
11
SENSE
13
12
10
9
12V
IN
–
+
–
+
5V
OUT
3V
OUT
62µA
+
–
+
Q8
Q7
–
Q5
200µA
2.5V
UVL
2.5V
UVL
C
C
P3
+
–
ON/ON
FAULT
5
6
Q3
REF
REF
LOGIC
P4
+
–
7
PWRGD
Q4
12V
IN
REF
9.5V
UVL
Q9
Q1
Q2
22µA
C
P7
C
P5
+
–
+
–
Q6
Q10
REF
1643A BD
LTC1643AH/LTC1643AL
ONLY
LTC1643AH/LTC1643AL
ONLY
1
16
12V
4
TIMER
2
15
8
GND
12V
IN
V
V
EEOUT
OUT
EEIN
U
W U U
APPLICATIONS INFORMATION
Hot Circuit Insertion
boardtobesafelyinsertedorremovedfromalivePCIslot
without glitching the system power supplies. The chip
also protects the PCI supplies from shorts and monitors
the supply voltages.
When a circuit board is inserted into a live PCI slot, the
supply bypass capacitors on the board can draw huge
transient currents from the PCI power bus as they charge
up. The transient currents can cause permanent damage
totheconnectorpinsandcauseglitchesonthepowerbus,
causing other boards in the system to reset.
The LTC1643AH is designed for motherboard applica-
tions, while the LTC1643AL/LTC1643AL-1 are designed
for CompactPCI applications where the chip resides on
the plug-in board.
The LTC1643A is designed to turn a board’s supply
voltages on and off in a controlled manner, allowing the
1643afb
8
LTC1643AL
LTC1643AL-1/LTC1643AH
U
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APPLICATIONS INFORMATION
LTC1643A FEATURE SUMMARY
Some ±12V supplies in CompactPCI applications are not
well regulated and can violate the tolerance specification.
For these applications, the LTC1643AL-1 should be used
because the PWRGD signal does not depend on ±12V
outputs.
1. Allows safe board insertion and removal from either a
motherboard (LTC1643AH) or CompactPCI board
(LTC1643AL/LTC1643AL-1).
2. Controls all four PCI supplies: –12V, 12V, 3.3V and 5V.
Power-Up Sequence
3. Programmable foldback current limit: a programmable
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.
The power supplies are controlled by placing external
N-channel pass transistors in the 3.3V and 5V power
paths, and internal pass transistors for the 12V and –12V
power paths (Figure 1).
4. Programmable circuit breaker: if a supply remains in
current limit too long, the circuit breaker will trip, the
supplieswillbeturnedoffandtheFAULTpinpulledlow.
Resistors R1 and R2 provide current fault detection and
R7 and C1 provide current control loop compensation.
Resistors R5 and R6 prevent high frequency oscillations
in Q1 and Q2.
5. Current limit power-up: the supplies are allowed to
power up in current limit. Allows the chip to power up
boards with widely varying capacitive loads without
tripping the circuit breaker. The maximum allowable
power-up time is programmable using the TIMER pin.
WhentheONpin(Pin5)ispulledhigh,thepasstransistors
are allowed to turn on and a 22µA current source is
connected to the TIMER pin (Pin 4) (Figure 2).
The current in each pass transistor increases until it
reaches the current limit for each supply. Each supply is
then allowed to power up at the rate dv/dt = 62µA/C1 or as
determined by the current limit and the load capacitance
whichever is slower. Current limit faults are ignored while
the TIMER pin (Pin 4) voltage is ramping up and is less
than 0.9V below 12VIN (Pin 1). Once all four supply
voltages are within tolerance, the PWRGD pin (Pin 7) will
pull low.
6. –12V and 12V power switches on chip.
7. Power good output: monitors the voltage status of the
four supply voltages, except the LTC1643AL-1 which
only monitors 3VOUT and 5VOUT
.
8. Space saving 16-pin SSOP package.
PCI Power Requirements
PCI systems usually require four power rails: 5V, 3.3V,
12V and –12V. Systems implementing the 3.3V signaling
environmentareusuallyrequiredtoprovideallfourrailsin
every system. Systems implementing the 5V signaling
environment may either ship the 3.3V supply with the
system or provide a means to add it afterward. The
tolerance of the supplies as measured at the components
on the plug-in card is summarized in Table 1.
Power-Down Sequence
When the ON pin (Pin 5) is pulled low, a power-down
sequence begins (Figure 3).
Internal switches are connected to each of the output
supply voltage pins to discharge the bypass capacitors to
ground. The TIMER pin (Pin 4) is immediately pulled low.
The GATE pin (Pin 11) is pulled down by a 200µA current
source to prevent the load currents on the 3.3V and 5V
supplies from going to zero instantaneously and glitching
the power supply voltages. When any of the output
voltages dip below its threshold, the PWRGD pin (Pin 7)
pulls high.
Table 1. PCI Power Supply Requirements
CAPACITIVE
SUPPLY
TOLERANCE
LOAD
5V
5V ±5%
<3000µF
<3000µF
<500µF
<120µF
3.3V
12V
3.3V ±0.3V
12V ±5%
–12V
–12V ±10%
1643afb
9
LTC1643AL
LTC1643AL-1/LTC1643AH
U
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APPLICATIONS INFORMATION
R1
0.007Ω
Q1
IRF7413
1
2
5V
5A
3
4
R6
10Ω
R2
0.005Ω
Q2
IRF7413
1
2
3.3V
7.6A
3
4
GND
SYSTEM
POWER
SUPPLY
R5
10Ω
R7
100Ω
C1
0.047µF
9
10
11
3
13
12
14
3V
IN
3V
GATE 3V
5V
IN
5V
SENSE
5V
SENSE
OUT
OUT
8
GND
1
2
12V
IN
V
EEIN
16
5
6
7
12V
12V
OUT
ON
500mA
LTC1643AH
R3
15
4
–12V
100mA
V
EEOUT
10k
PCI
FAULT
POWER
SYSTEM
CONTROLLER
TIMER
R4
10k
C2
0.1µF
PWRGD
LOGIC
RESET
RESET
1643A F01
Figure 1. Typical PCI Application
ON
10V/DIV
ON
10V/DIV
TIMER
10V/DIV
TIMER
10V/DIV
GATE
10V/DIV
GATE
10V/DIV
12V
OUT
5V/DIV
12V
OUT
5V
5V/DIV
OUT
5V/DIV
5V
5V/DIV
3V
5V/DIV
3V
5V/DIV
OUT
OUT
OUT
V
EEOUT
V
EEOUT
5V/DIV
5V/DIV
FAULT
10V/DIV
FAULT
10V/DIV
PWRGD
10V/DIV
PWRGD
10V/DIV
Figure 3. Normal Power-Down Sequence
Figure 2. Normal Power-Up Sequence
1643afb
10
LTC1643AL
LTC1643AL-1/LTC1643AH
U
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APPLICATIONS INFORMATION
Timer
turningon—fromcausingfalsetripsofthecircuitbreaker.
The chip will stay in the latched-off state until ON pin
(Pin 5) is cycled low then high, or the 12VIN pin (Pin 1)
power supply is cycled.
During a power-up sequence, a 22µA current source is
connected to the TIMER pin (Pin 4) and current limit faults
are ignored until the voltage ramps to within 0.9V of 12VIN
(Pin 1). This feature allows the chip to power up a PCI slot
that can accept boards with widely varying capacitive
loads on the supplies. The power-up time will be:
To prevent excessive power dissipation in the pass tran-
sistors and to prevent voltage spikes on the supplies
during short-circuit conditions, the current limit on each
supply is designed to be a function of the output voltage.
As the output voltage drops, the current limit decreases.
Unlike a traditional circuit breaker function where huge
currents can flow before the breaker trips, the current
foldback feature assures that the supply current will be
kept at a safe level and prevent voltage glitches when
powering up into a short.
CSUPPLY • VSUPPLY
tON ≅ 2
ILIMIT −ILOAD
For CSUPPLY = 2000µF, VSUPPLY = 5V, ILIMIT = 7A, ILOAD
= 5A, the turn-on time will be ~10ms. The timer period
should be set longer than the maximum supply turn-on
time but short enough to not exceed the maximum safe
operating area of the pass transistor during a short circuit.
The timer period will be:
The current limit for the 5V and 3.3V supplies is set by
placingasenseresistorbetween5VIN (Pin13)and5VSENSE
(Pin 12) and between 3VIN (Pin 9) and 3VSENSE (Pin 10).
The current limit will be set by:
1
•11. V
22µA
CTIMER
tTIMER
=
ILIMIT = 53mV/RSENSE
For CTIMER = 0.1µF, the timer period will be ~50ms. The
TIMER pin (Pin 4) is immediately pulled low when ON
(Pin 5) goes low.
For a 0.005Ω resistor, the current limit will be set at 10.6A
and fold back to 1.5A when the output is shorted. For a
0.007Ω resistor, the current limit will be set at 7.6A and
fold back to 1.1A when the output is shorted.
Thermal Shutdown
The current limit for the internal 12V switch is set at
850mA folding back to 250mA and the –12V switch at
450mA folding back to 160mA.
The internal switches for the 12V and –12V supplies are
protected by an internal current limit and thermal shut-
down circuit. When the temperature of chip reaches
150°C, all switches will be latched off and the FAULT pin
(Pin 6) will be pulled low.
In systems where it is possible to exceed the current limit
for a short amount of time, it might be necessary to
prevent the analog current loop from responding quickly
so the output voltage does not droop. This can be accom-
plished by adding an RC filter across the sense resistor as
shown in Figure 6. R4 should be 20Ω or less to prevent
offset errors. A 0.1µF capacitor gives a delay of about
1.5µs and a 1µF capacitor gives a delay of about 15µs.
Short-Circuit Protection
During a normal power-up sequence, if the TIMER (Pin 4)
is done ramping and a supply is still in current limit, all of
the pass transistors will be immediately turned off and the
FAULT pin (Pin 6) will be pulled low as shown in Figure 4.
If a short circuit occurs after the supplies are powered up,
the shorted supply’s current will drop immediately to the
limit value (Figure 5).
CompactPCI Application
TheLTC1643ALisdesignedforhotswappingCompactPCI
boards. The typical application is shown in Figure 7. The
3.3V, 5V, 12V and –12V inputs to the LTC1643AL come
fromthemediumlengthpowerpins.Thelong3.3V,5Vand
V(I/O) pins power up the pull-up resistors, bus precharge
Ifthesupplyremainsincurrentlimitformorethan14.6µs,
all of the supplies will be latched off. The 14.6µs delay
prevents quick current spikes—for example, from a fan
1643afb
11
LTC1643AL
LTC1643AL-1/LTC1643AH
U
W U U
APPLICATIONS INFORMATION
ON
10V/DIV
ON
10V/DIV
TIMER
10V/DIV
TIMER
10V/DIV
GATE
10V/DIV
GATE
10V/DIV
12V
OUT
5V/DIV
12V
OUT
5V/DIV
5V
OUT
5V/DIV
3V
OUT
5V/DIV
3V
OUT
5V/DIV
5V
OUT
5V/DIV
V
EEOUT
V
5V/DIV
EEOUT
5V/DIV
FAULT
10V/DIV
FAULT
10V/DIV
PWRGD
10V/DIV
PWRGD
10V/DIV
Figure 4. Power-Up into a Short on 3.3V Output
Figure 5. Short Circuit on 5V Followed by Circuit Breaker Reset
R1
0.007Ω
Q1
IRF7413
1
2
5V
5A
5V
3
4
R6
R2
0.005Ω
Q2
IRF7413
R4
20Ω 10Ω
1
2
3.3V
7.6A
3.3V
C3
1µF
3
4
C2
1µF
R3
20Ω
R5
10Ω
R7
100Ω
C1
0.047µF
9
10
11
GATE 3V
3
12
14
OUT
13
3V
3V
5V
5V
5V
IN
SENSE
OUT
IN
SENSE
LTC1643AL
1643A F06
Figure 6. Delay in the Current Limit Loop
1643afb
12
LTC1643AL
LTC1643AL-1/LTC1643AH
U
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APPLICATIONS INFORMATION
R2
0.007Ω
1%
Q1
IRF7413
2
1
5V
5A
MED 5V
R1
3
4
Q2
IRF7413
0.005Ω
1%
1
2
3.3V
7.6A
MED 3.3V
3
4
R4
10Ω
5%
R5
100Ω
5%
R3
10Ω
R11
10Ω
5%
5%
†
V(I/O)
C1
0.047µF
9
10
11
GATE 3V
3
13
IN
12
14
D3*
12V
R8
1.2k
5%
C6
0.1µF
3V
3V
5V
5V
5V
IN
SENSE
OUT
SENSE
OUT
1
2
5
16
15
12V
12V
12V
IN
12V
OUT
500mA
–12V
R12 3Ω 5%
LONG
3.3V
V
–12V
EEIN
V
EEOUT
100mA
R9 2k 5%
V(I/O)
R10 2k 5%
BD_SEL#
ON
LTC1643AL
PRECHARGE OUT
D1
1N4148
1V ±20%
V(I/O)
LT1117
IN
I
= ±40mA
6
7
OUT
R13
FAULT
OUT
ADJ
D2*
12V
2k
R6
130Ω
1%
R7
56.2Ω
1%
C3
0.01µF
5%
HEALTHY#
LONG GND
PWRGD
TIMER
4
R11
24Ω
5%
GND
C5
0.1µF
8
C4
1µF
C2
0.1µF
V(I/O)
R13
10k
5%
LONG LONG
LOCAL_PCI_RESET#
3.3V
5V
R14
10Ω, 5%
PCI_RST#
I/O
DATA LINE EXAMPLE
DATA BUS
I/O
5V
3.3V
RESET#
PCI
BRIDGE
(21154)
1643A F07
* BZX84C15 (SOT-23)
†
VALUE MAY VARY FOR BACKPLANES WITHOUT BYPASS CAPACITANCE
Figure 7. Typical CompactPCI Application
LTC1643AL-1
circuit, PCIbridgechipandtheLOCAL_PCI_RESET#logic
circuitry. The BD_SEL# signal is connected to the ON pin
while the PWRGD pin is connected to the HEALTHY#
signal. The HEATHLY# signal is combined with the
PCI_RESET# signal to generate the LOCAL_PCI_RESET#
signal. Capacitors C6 and C7 provide chip bypassing on
the 12V and –12V inputs. Diode D2 protects the part from
voltage surges below –13.2V on the –12V supply.
The LTC1643AL-1 is designed for CompactPCI designs
where the ±12V supplies are not being used on the board
or the supplies are not well regulated. The power good
comparators on the 12VOUT and VEEOUT pins are disabled.
The VEEIN pin can be connected to GND and the part will
still operate normally if a –12VOUT output is not needed.
However, 12V is still required at the 12VIN pin for the part
to function. Refer to Figure 10 for a typical LTC1643AL-1
application circuit.
The 1V precharge voltage for the data bus lines is gener-
atedbyanLT1117lowdropoutregulator.Theoutputofthe
LT1117 is set to 1.8V, then the voltage is dropped by a
1N4148 diode to generate 1V. The precharge circuit is
capable of sourcing and sinking 40mA.
1643afb
13
LTC1643AL
LTC1643AL-1/LTC1643AH
U
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APPLICATIONS INFORMATION
Increasing 12V and –12V Current Capability
for PCI Applications
be reached when the internal current reaches 1A and the
external current is 2A or 3A load current.
TheinternalswitchesoftheLTC1643Aaredesignedforup
to 500mA loads on 12V and 200mA on –12V. If more
currentisneeded, thenthecircuitsinFigure8canbeused.
For the –12V supply, N-channel transistor Q6 is used to
provide the extra load current. When the LTC1643AH is
turned on, the internal VEE switch is turned on and the
–12V output starts to pull down through D1 and turns on
Q5. WhenQ5turnson, thegateofQ6startstorise, turning
it on. When the LTC1643AH turns off, the VEEOUT pin is
pulled up to ground, diode D1 is reversed biased, and
transistor Q5 turns off, which allows resistor R10 to turn
off Q6.
For the 12V supply, P-channel transistor Q4 is placed in
parallel with the internal switch. When the LTC1643AH 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 LTC1643AH 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.
The internal –12V switch provides the current limit for the
supply, butbecausethehighRDS(ON) oftheinternalswitch
(1.2Ω) 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.
Because Q4 is in parallel with the internal 12V switch, the
loadcurrentwillbesharedinproportiontotheirrespective
RDS(ON) values. For example, if the RDS(ON) of the external
switch is 0.2Ω and the internal switch is 0.4Ω, then, at
1.5A load current, the external switch will provide 1A and
the internal switch 500mA. The circuit breaker current will
Q4
Si9400
12V
1.5A
Q3
TP0610T
10Ω
C3
0.1µF
R8
100k
Q1
IRF7413
1
2
5V
5A
R1
0.007Ω
3
4
R2
0.005Ω
Q2
IRF7413
SYSTEM
POWER
SUPPLY
1
2
3.3V
7.6A
3
4
R6
10Ω
GND
R5
10Ω
R7
100Ω
C1
0.047µF
1
16
9
10
11
3
13
12
12V 3V
IN
3V
GATE 3V
5V
IN
12V
V
5V
SENSE
IN
SENSE
OUT
OUT
8
GND
Q5
TP0610T
2
5
V
EEIN
15
4
ON
EEOUT
LTC1643AH
D1
1N4148
R3
R9
10k
200Ω
6
7
PCI
FAULT
PWRGD
POWER
TIMER
SYSTEM
CONTROLLER
R4
10k
C2
0.1µF
R10
200Ω
–12V
1.5A
Q6
Si9410DY
NOTE: INTENDED FOR PCI APPLICATIONS ONLY
1643A F08
Figure 8. Increasing 12V and –12V Current Capability for PCI Applications
1643afb
14
LTC1643AL
LTC1643AL-1/LTC1643AH
U
PACKAGE DESCRIPTION
GN Package
16-Lead Plastic SSOP (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1641)
.189 – .196*
(4.801 – 4.978)
.045 ±.005
.009
(0.229)
REF
16 15 14 13 12 11 10 9
.254 MIN
.150 – .165
.229 – .244
.150 – .157**
(5.817 – 6.198)
(3.810 – 3.988)
.0165 ± .0015
.0250 TYP
RECOMMENDED SOLDER PAD LAYOUT
1
2
3
4
5
6
7
8
.015 ± .004
(0.38 ± 0.10)
× 45°
.053 – .068
(1.351 – 1.727)
.004 – .0098
(0.102 – 0.249)
.007 – .0098
(0.178 – 0.249)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
.0250
(0.635)
BSC
.008 – .012
(0.203 – 0.305)
NOTE:
1. CONTROLLING DIMENSION: INCHES
INCHES
2. DIMENSIONS ARE IN
(MILLIMETERS)
GN16 (SSOP) 0502
3. DRAWING NOT TO SCALE
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
U
TYPICAL APPLICATIONS
R1
0.007Ω
Q1
IRF7413
1
2
5V
5A
3
4
GND
R6
10Ω
R7
100Ω
SYSTEM
POWER
SUPPLY
C1
0.047µF
9
13
10
12
11
GATE
3
14
3V
5V
3V
5V
3V
5V
IN
IN
SENSE
SENSE
OUT
OUT
8
GND
1
2
12V
IN
V
EEIN
16
15
4
5
6
7
12V
12V
OUT
ON
500mA
LTC1643AH
R3
–12V
100mA
PCI
V
EEOUT
10k
POWER
FAULT
SYSTEM
CONTROLLER
TIMER
R4
10k
C2
0.1µF
PWRGD
1643A G09
Figure 9. System Without 3.3V Supply
1643afb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC1643AL
LTC1643AL-1/LTC1643AH
U
TYPICAL APPLICATIONS
R2
0.007Ω
1%
Q1
IRF7413
1
2
5V
5A
MED 5V
R1
0.005Ω
1%
3
4
Q2
IRF7413
1
2
3.3V
7.6A
MED 3.3V
3
4
R4
10Ω
5%
R5
100Ω
5%
R3
V(I/O)
10Ω
5%
C1
9
10
11
GATE 3V
3
13
IN
12
14
R8
R9
2k
5%
D2*
12V
0.047µF
1.2k
5%
3V
3V
5V
5V
5V
IN
SENSE
OUT
SENSE
OUT
1
2
5
16
12V
12V
IN
12V
NC
NC
OUT
R12
2k
15
LONG
3.3V
V
EEIN
V
EEOUT
5%
BD_SEL#
ON
LTC1643AL-1
PRECHARGE OUT
D1
1V ±20%
V(I/O)
6
LT1117
IN
1N4148
FAULT
I
= ±40mA
OUT
R11
R10
†
OUT
ADJ
1Ω
5%
2k
R6
130Ω
1%
R7
56.2Ω
1%
C3
0.01µF
5%
7
HEALTHY#
LONG GND
PWRGD
TIMER
4
R15
24Ω
5%
GND
8
C4
1µF
C7
0.1µF
C2
0.1µF
V(I/O)
R13
10k
5%
LONG LONG
LOCAL_PCI_RESET#
3.3V
5V
R14
10Ω, 5%
PCI_RST#
I/O
DATA LINE EXAMPLE
DATA BUS
I/O
5V
3.3V
RESET#
PCI
BRIDGE
(21154)
1643A F10
* BZX84C15 (SOT-23)
†
VALUE MAY VARY FOR BACKPLANES WITHOUT BYPASS CAPACITANCE
Figure 10. CompactPCI Application without ±12V Outputs
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC1421
Hot Swap Controller
Multiple Supplies from 3V to 12V and –12V
LTC1422
Hot Swap Controller in SO-8
Single Supply form 3V to 12V, RESET Output
–10V to –80V Supplies
LT®1640A
LT1641-1/LT1641-2
LTC1642
–48V Hot Swap Controller in SO-8
Positive High Voltage Hot Swap Controller in SO-8
Fault Protected Hot Swap Controller
CompactPCI Hot Swap Controller
2-Channel Hot Swap Controller
Operates from 9V to 80V, Active Current Limiting
Operation Up to 15V, Handles Surges to 33V
3.3V, 5V, ±12V, Local Reset Logic, 1V Precharge
Operates from 1.2V to 12V, Power Sequencing
LTC1644
LTC1645
LTC1646
Dual CompactPCI Hot Swap Controller
Dual Hot Swap Controller
3.3V, 5V Supplies, 1V Precharge, Local Reset Logic
Dual ON Pins for Supplies from 3V to 15V
LTC1647
LTC4211
Hot Swap Controller with Multifunction Current Control
Triple Hot Swap Controller
2.5V to 16.5V Operation, MSOP
LTC4230
1.7V to 16.5V Operation, Multifunction Current Control
–20V to –80V Supplies, Active Current Limiting
–15V Minimum Floating Supply, Active Current Limiting
Floating Supply, Power Good, Active Current Limiting
LT4250
–48V Hot Swap Controller in SO-8
–48V Hot Swap Controller in SOT-23
–48V Hot Swap Controller in MSOP
LTC4251
LTC4252
1643afb
LT/LWI 1006 REV B • PRINTED IN USA
16 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2002
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