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1
LTC4221
4221f
Dual Hot Swap Controller/
Power Sequencer with Dual Speed,
Dual Level Fault Protection
Allows Safe Board Insertion and Removal from a
Live Backplane
Configurable Power Supply Sequencing
Soft-Start with Current Foldback Limits Inrush
Current
No External Gate Capacitor Required
Adjustable Dual Level Circuit Breaker Protection
Controls Supply Voltages from 1V to 13.5V
Independent N-Channel MOSFET High Side Drivers
FB
Pin Monitors V
OUT
for Overvoltage Protection
Latch Off or Automatic Retry on Current Fault
FAULT and PWRGD Outputs
Narrow 16-Pin SSOP Package
Electronic Circuit Breaker
Power Supply Sequencing
Live Board Insertion and Removal
Industrial High Side Switch/Circuit Breaker
The LTC
4221 is a 2-channel Hot Swap
TM
controller that
allows a board to be safely inserted and removed from a
live backplane. Using two independent high side gate
drivers to control two external N-channel pass transistors,
the output voltages can be ramped up with current foldback
to limit the inrush current during the start-up period. No
external compensation capacitors are required at the
GATE pins. The two channels can be configured to ramp up
and down separately or simultaneously for supply volt-
ages ranging from 2.7V to 13.5V and 1V to 13.5V for
channels 1 and 2 respectively.
Each channel has two current limit comparators that
provide dual level and dual speed overcurrent circuit
breaker protection after the start-up period. If any current
sense voltage exceeds 100mV for 1s or 25mV for the
timeout delay (set by the C
FILTER
at the FILTER pin), then
the FAULT latch is set and both GATE pins are pulled low.
The FB pins monitor the respective channel output volt-
ages and provide the inputs for the PWRGD comparators
as well as overvoltage protection.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
2-Channel Hot Swap Controller
ON2
FAULT
GND
LTC4221
FB2
PWRGD2
PWRGD1
PWRGD2
V
OUT1
3.3V/5A
V
OUT2
2.5V/5A
PWRGD1
FB1
LONG
LONG
SHORT
GND
FAULT
LONG
*SMAJ10 (OPTIONAL)
SHORT
TIMER
FILTER
ON1
V
CC1
SENSE1 GATE1 V
CC2
SENSE2 GATE2
SHORT
V
CC1
3.3V
V
CC2
2.5V
BACKPLANE
CONNECTOR
(FEMALE)
PCB EDGE
CONNECTOR
(MALE)
10
21k
13.3k
10k
10k
10
14.3k
IRF7413
5.11k
10k
10k
20k
5.11k
4221 TA01
100nF
*
*
1nF
470nF
100nF
IRF7413
0.004
0.004
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LTC4221
4221f
ORDER PART
NUMBER
(Note 1)
Supply Voltage (V
CC
n
) ............................................ 17V
SENSE
n Pins ............................ 0.3V to (V
CC
n
+ 0.3V)
FB, ON Pins .............................. 0.3V to (V
CC1
+ 0.3V)
TIMER Pin .................................................. 0.3V to 2V
GATE Pins (Note 3) ................................... 0.3V to 21V
PWRGD, FAULT, FILTER Pins ................... 0.3V to 17V
Operating Temperature Range
LTC4221C ............................................... 0C to 70C
LTC4221I ............................................ 40C to 85C
Storage Temperature Range ................. 65C to 150C
Lead Temperature (Soldering, 10 sec).................. 300C
LTC4221CGN
LTC4221IGN
T
JMAX
= 125C,
JA
= 130C/W
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC1
Supply Voltage Channel 1
2.7
13.5
V
V
CC2
Supply Voltage Channel 2
V
CC2
V
CC1
1
13.5
V
I
CC1
V
CC1
Supply Current
ON1, ON2 = 2V
2.2
3
mA
I
CC2
V
CC2
Supply Current
ON1, ON2 = 2V
0.05
0.15
mA
V
CC1(UVL)
Undervoltage Lockout for Channel 1
V
CC1
Rising
2.1
2.5
2.675
V
V
CC1(HYST)
Undervoltage Lockout Hysteresis
110
mV
V
CC2(UVL)
Undervoltage Lockout for Channel 2
V
CC2
Rising
0.65
0.8
0.975
V
V
CC2(HYST)
Undervoltage Lockout Hysteresis
25
mV
I
SENSE1(IN)
SENSE1 Pin Input Current
0V V
SENSE1
V
CC1
0.03
5
A
I
SENSE2(IN)
SENSE2 Pin Input Current
V
SENSE2
= V
CC2
0.2
5
A
V
SENSE2
= 0V
1000
A
V
SENSE(FC)
SENSE
n Threshold Voltage
Channel
n Fast Comparator Threshold
85
100
115
mV
V
SENSE(SC)
SENSE
n Threshold Voltage
Channel
n Slow Comparator Threshold
22.5
25
27.5
mV
20.5
25
29.5
mV
V
SENSE(ACL)
SENSE
n Voltage at Active
V
FB
n
= 0
9
mV
Current Limit
V
FB
n
= 0.65V
25
mV
I
GATE(UP)
GATE
n Output Current
V
ON1
= V
ON2
= 2V, V
GATE
n
= 0V
7
9.5
12
A
I
GATE(DN)
GATE
n Output Current
V
ON1
= V
ON2
= 0.6V, V
GATE
n
= 3.3V
75
100
125
A
I
GATE(FSTDN)
GATE
n Output Current
UVLO with V
GATE
n
= 3.3V or FAULT
16
mA
Latched with V
GATE
n
= 3.3V
V
GATE
External N-Channel Gate Drive
V
GATE
n
V
CC1
for V
CC1
= 2.7V, V
CC2
= 1V
4.5
13
V
V
GATE
n
V
CC1
for V
CC1
= 3.3V, V
CC2
= 2.5V
5
16
V
V
GATE
n
V
CC1
for V
CC1
= 5V, V
CC2
= 3.3V
8
16
V
V
GATE
n
V
CC1
for V
CC1
= 12V, V
CC2
= 12V
7
18
V
V
GATE(OV)
GATE
n Overvoltage Lockout Threshold
0.4
0.5
V
I
ON(IN)
ON
n Pin Input Current
0V V
ON
n
V
CC1
0.01
1
A
V
ON(RESET)
ON1 Reset Threshold
V
ON1
Falling
0.375
0.4
0.425
V
V
ON(RESETHYST)
ON1 Reset Threshold Hysteresis
25
mV
The
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25C. V
CC1
= 5V, V
CC2
= 3.3V, unless otherwise noted.
GN PACKAGE
16-LEAD PLASTIC SSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
ON1
V
CC1
SENSE1
GATE1
FB1
PWRGD1
FAULT
FILTER
ON2
V
CC2
SENSE2
GATE2
FB2
PWRGD2
GND
TIMER
GN PART
MARKING
4221
4221I
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
3
LTC4221
4221f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
ON(OFF)
ON
n Off Threshold
High to Low, GATE
n Turns Off by 100A
0.796
0.821
0.846
V
Pull-Down
V
ON(OFFHYST)
ON
n Off Threshold Hysteresis
30
mV
I
FB(IN)
FB
n Input Current
0V V
FB
n
V
CC
n
0.01
1
A
V
FB(UV)
FB
n Undervoltage Threshold
FB
n Falling
0.605
0.617
0.629
V
V
FB(UVHYST)
FB
n Undervoltage Threshold Hysteresis
3
mV
V
FB(LREG)
FB
n Threshold Line Regulation
2.7V V
CC1
13.5V
2
mV
V
FB(OV)
FB
n Overvoltage Threshold
FB
n Rising
0.805
0.822
0.838
V
I
FILTER(UP)
FILTER Pull-Up Current
During Current Fault Condition
80
105
132
A
I
FILTER(DN)
FILTER Pull-Down Current
During Normal Cycle
1.15
1.8
2.45
A
V
FILTER(TH)
FILTER Threshold
Latched Off Threshold, FILTER Rising
1.18
1.24
1.30
V
V
FILTER(HYST)
FILTER Threshold Hysteresis
105
mV
I
TMR(UP1)
TIMER Pull-Up Current 1
Initial Timing Cycle
1.2
1.9
2.6
A
I
TMR(UP2)
TIMER Pull-Up Current 2
Start-Up Cycle
15
20
25
A
I
TMR(FSTDN)
TIMER Pull-Down Current
V
TIMER
= 1.5V, End of Initial Timing Cycle
9
mA
V
TMR(H)
TIMER High Threshold
TIMER Rising
1.172
1.234
1.27
V
V
TMR(L)
TIMER Low Threshold
TIMER Falling
0.1
0.4
0.5
V
I
FAULT(UP)
FAULT Pull-Up Current
2.5
3.8
5
A
V
FAULT(TH)
FAULT Threshold
FAULT Falling
0.791
0.816
0.841
V
V
FAULT(HYST)
FAULT Hysteresis
35
mV
V
FAULT(OL)
FAULT Output Low Voltage
I
FAULT
= 1.6mA, V
CC1
= 5V
0.14
0.4
V
I
PWRGD(LK)
PWRGD
n Leakage Current
V
PWRGD
n
= V
CC1
, V
FB
n
= 0.7V, Normal Cycle
0.01
10
A
V
PWRGD(OL)
PWRGD
n Output Low Voltage
I
PWRGD
n
= 1.6mA, V
CC1
= 5V, V
FB
n
= 0V,
0.14
0.4
V
Normal Cycle
t
P(FC-GATE)
Fast Comparator Trip to GATE
n
V
SENSE
n
= V
CC
n
to (V
CC
n
200mV) Step
1
1.5
s
Discharging
t
P(SC-FAULT)
Slow Comparator Trip to FILTER
V
SENSE
n
= V
CC
n
to (V
CC
n
50mV) Step.
15
35
s
High and FAULT Latched
FILTER Open
t
P(FAULT-GATE)
FAULT Low to GATE
n Discharging
V
FAULT
= 3.3V to 0V
15
35
s
t
P(OV-GATE)
FB
n OV Comparator Trip to GATEn
V
FB
n
= 0V to 1V
18
35
s
Discharging
t
P(FILTER-GATE)
Filter Comparator Trip to GATE
n
V
FILTER
= 0V to 1.5V
15
35
s
Discharging
t
RESET
Circuit Breaker Reset Delay Time
V
ON1
< 0.4V to FAULT High
15
30
s
t
P(ON-GATE)
Turn Off Propagation Delay
V
ON
n
0.821V to GATEn Discharging
15
35
s
The
indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25C. V
CC1
= 5V, V
CC2
= 3.3V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: All current into device pins are positive. All voltages are referenced
to ground unless otherwise specified.
Note 3: An internal zener on each GATE pin clamps the charge pump
voltage to a typical maximum operating voltage of 26V. External overdrive
of either GATE pin beyond its internal zener voltage may damage the
device.
4
LTC4221
4221f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
I
CC1
vs Temperature
TEMPERATURE (C)
50
I
CC1
(mA)
4
5
6
25
75
4221 G01
3
2
25
0
50
100
125
1
0
V
CC2
= 1V
V
CC1
= 13.5V
V
CC1
= 12V
V
CC1
= 5V
V
CC1
= 2.7V
TEMPERATURE (C)
50
I
CC2
(mA)
0.175
25
4221 G02
0.100
0.050
25
0
50
0.025
0
0.200
0.150
0.125
0.075
75
100
125
V
CC1
= 13.5V
V
CC2
= 13.5V
V
CC2
= 12V
V
CC2
= 5V
V
CC2
= 3.3V
V
CC2
= 1V
TEMPERATURE (C)
50
V
CC1(UVL)
(V)
2.50
25
4221 G03
2.44
2.40
25
0
50
2.38
2.36
2.52
2.48
2.46
2.42
75
100
125
TIMER = 0.3V
RISING
FALLING
I
CC2
vs Temperature
V
CC1(UVL)
vs Temperature
V
CC2(UVL)
vs Temperature
|I
SENSE2(IN)
| vs V
SENSE2
V
SENSE(FC)
vs V
CC1
TEMPERATURE (C)
50
0.770
V
CC2(UVL)
(V)
0.775
0.785
0.790
0.795
50
0.815
4221 G04
0.780
0
25
75
100
25
125
0.800
0.805
0.810
TIMER = 0.3V
RISING
FALLING
V
SENSE2
(V)
0
|I
SENSE2(IN)
| (
A)
1000
6
4221 G05
1
0.01
2
4
8
0.001
0.0001
10000
100
10
0.1
10
12
V
CC1
= 2.7V, V
CC2
= 1V
V
CC1
= 5V, V
CC2
= 3.3V
V
CC1
= 13.5V, V
CC2
= 13.5V
V
CC1
(V)
0
V
SENSE(FC)
(mV)
101.0
101.5
102.0
6
10
16
4221 G06
100.5
100.0
99.5
2
4
8
12
14
V
CC2
= V
CC1
T
A
= 25C
V
SENSE(FC)
vs Temperature
V
SENSE(SC)
vs V
CC1
V
SENSE(SC)
vs Temperature
TEMPERATURE (C)
50
V
SENSE(FC)
(mV)
101.0
101.5
102.0
25
75
4221 G07
100.5
100.0
25
0
50
100
125
99.5
99.0
V
CC1
= 5V
V
CC2
= 3.3V
V
CC1
(V)
0
V
SENSE(SC)
(mV) 25.0
25.2
25.4
12
4221 G08
24.8
24.6
4
8
2
14
6
10
16
24.4
24.2
25.6
V
CC2
= V
CC1
T
A
= 25C
TEMPERATURE (C)
50
V
SENSE(SC)
(mV)
25.8
25
4221 G09
25.2
24.8
25
0
50
24.6
24.4
26.0
25.6
25.4
25.0
75
100
125
V
CC1
= 5V
V
CC2
= 3.3V
5
LTC4221
4221f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
V
SENSE(ACL)
vs V
FB
I
GATE(UP)
vs Temperature
I
GATE(DN)
vs Temperature
I
GATE(FSTDN)
vs Temperature
V
GATE
n
(V
GATE
n
V
CC1
) vs V
CC1
V
GATE(OV)
vs Temperature
V
ON(RESET)
vs V
CC1
V
FB
(V)
0
V
SENSE(ACL)
(mV)
20
25
30
0.3
0.5
4221 G10
15
10
0.1
0.2
0.4
0.6
0.7
5
0
V
CC1
= 5V
V
CC2
= 3.3V
T
A
= 25C
TEMPERATURE (C)
50
I
GATE(UP)
(
A)
8
7
6
25
75
4221 G11
9
10
25
0
50
100
125
11
12
V
CC1
= 2.7V
V
CC1
= 5V
V
CC1
= 13.5V
V
CC2
= 1V
V
GATE
= 0V
TEMPERATURE (C)
50
101
102
104
25
75
4221 G12
100
99
25
0
50
100
125
98
97
103
I
GATE(DN)
(
A)
V
CC1
= 2.7V
V
CC1
= 5V
V
CC1
= 13.5V
V
CC2
= 1V
V
GATE
= 3.3V
TEMPERATURE (C)
50
I
GATE(FSTDN)
(mA)
40
50
60
25
75
4221 G13
30
20
25
0
50
100
125
10
0
V
CC1
= 2.7V
V
CC1
= 5V
V
CC1
= 13.5V
V
CC2
= 1V
V
GATE
= 3.3V
V
CC1
(V)
0
6
V
GATE
n
(V)
7
9
10
11
8
15
4221 G14
8
4
2
10
12
6
14
12
13
14
V
CC2
= V
CC1
1.5V
T
A
= 25C
V
GATE1
V
GATE2
V
GATE1
(V
GATE1
V
CC1
)
vs Temperature
TEMPERATURE (C)
50
12
14
18
25
75
4221 G15
10
8
25
0
50
100
125
6
4
16
V
GATE1
(V)
V
CC1
= 2.7V, V
CC2
= 1V
V
CC1
= 5V, V
CC2
= 3.3V
V
CC1
= 13.5V, V
CC2
= 13.5V
V
GATE2
(V
GATE2
V
CC1
)
vs Temperature
TEMPERATURE (C)
50
V
GATE2
(V)
12
14
16
25
75
4221 G16
10
8
25
0
50
100
125
6
4
V
CC1
= 2.7V, V
CC2
= 1V
V
CC1
= 5V, V
CC2
= 3.3V
V
CC1
= 13.5V, V
CC2
= 13.5V
TEMPERATURE (C)
50
0.375
V
GATE(OV)
(V)
0.385
0.390
0.395
50
0.420
4221 G17
0.380
0
25
75
100
25
125
0.405
0.400
0.410
0.415
V
CC1
= 2.7V
V
CC1
= 5V
V
CC1
= 13.5V
V
CC2
= 1V
TIMER = 0.5V
V
CC1
(V)
0
V
ON(RESET)
(V)
0.415
0.420
0.425
12
4221 G18
0.410
0.405
4
8
2
14
6
10
16
0.400
0.395
0.430
V
CC2
= 1V, T
A
= 25C
FALLING
RISING
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