LTC4212
Hot Swap Controller with
Power-Up Timeout
FEATURES
s
s
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DESCRIPTIO
s
s
s
s
s
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Allows Safe Board Insertion and Removal
from a Live Backplane
Controls Supply Voltages from 2.5V to 16.5V
Adjustable Soft-Start with Inrush Current
Limiting
Fast Turn-Off Time
No External Gate Capacitor is Required
Power Good Input with Adjustable Timer and
Glitch Filter
Power-Up Timeout Circuit Interfaces with External
Supply Monitors
Dual Level Overcurrent Fault Protection
Automatic Retry or Latched Mode Operation
High Side Drive for an External N-Channel FET
MS10 Package
The LTC
®
4212 is a Hot Swap
TM
controller that allows a
board to be safely inserted and removed from a live
backplane. An internal high side switch driver controls the
gate of an external N-channel MOSFET for supply voltages
ranging from 2.5V to 16.5V. The LTC4212 provides soft-
start and inrush current limiting during the start-up
period. It features a power-up timeout circuit that discon-
nects the system supply when the onboard supplies do not
enter into regulation within an adjustable timeout period.
The controller interfaces with external supply monitor ICs
or directly with the PGOOD pin of a DC/DC converter. After
normal power-up, a programmable power good glitch
filter can be enabled to filter out short term dips in the
supplies.
Two current limit comparators provide dual level
overcurrent circuit breaker protection. The slow com-
parator trips at V
CC
– 50mV and activates in 18µs. The fast
comparator trips at V
CC
– 150mV and typically responds
in 500ns.
The LTC4212 can be configured for both latchoff and
autoretry applications and is available in a 10-pin MSOP
package.
APPLICATIO S
s
s
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Electronic Circuit Breaker
Hot Board Insertion and Removal
Self-Isolating Hot Swap Boards
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
EDGE
BACKPLANE
CONNECTOR CONNECTOR
(MALE)
(FEMALE)
V
CC
5V
Z1
10Ω
100nF
10k
ON
10k
FAULT
20k
Hot Swap Controller with Power Good Function
0.007Ω
Si4410DY
+
10µF
5V
+
LT1963-2.5
10µF
+
10µF
2.5V
1.5A
V
CC
SENSE
GATE
10k
+
10k
LT1963-3.3
10µF
+
10µF
3.3V
1.5A
LTC4212
FAULT
GND
TIMER
PGI
PGT
PGF
2.1k
0.01µF
GND
Z1 = SMAJ10A (TVS)
4.7nF
270pF
V
CC3
V
CCA
LTC1727-2.5
COMP2.5 V
CC25
COMP3
COMP A GND
4212 TA01a
U
Power-Up Waveforms
ON
5V/DIV
TIMER
1V/DIV
PGT
1V/DIV
PGI
5V/DIV
U
U
5ms/DIV
4212f
1
LTC4212
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
ON
TIMER
PGT
PGF
GND
1
2
3
4
5
10
9
8
7
6
FAULT
V
CC
SENSE
GATE
PGI
Supply Voltage (V
CC
) ............................................... 17V
Input Voltages
ON, PGI ................................................ – 0.3V to 17V
SENSE .................................... – 0.3V to (V
CC
+ 0.3V)
TIMER, PGT, PGF ....................................– 0.3V to 2V
Output Voltages
GATE ............................... Internally Limited (Note 3)
FAULT .................................................. – 0.3V to 17V
Operating Temperature Range
LTC4212C .............................................. 0°C to 70°C
LTC4212I ........................................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC4212CMS
LTC4212IMS
MS PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/ W
MS PART
MARKING
LTC5
LTC6
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CC
I
CC
V
LKO
V
LKOHST
I
INON
I
LEAK
I
INPGI
I
INSENSE
V
CB(FAST)
V
CB(SLOW)
I
GATEUP
PARAMETER
V
CC
Supply Voltage Range
V
CC
Supply Current
Internal V
CC
Undervoltage Lockout
V
CC
Undervoltage Lockout Hysteresis
ON Input Current
FAULT Leakage Current
PGI Pin Input Current
SENSE Input Current
SENSE Trip Voltage (V
CC
– V
SENSE
)
SENSE Trip Voltage (V
CC
– V
SENSE
)
GATE Pull-Up Current
Fast GATE Pull-Down Current
∆V
GATE
External N-Channel Gate Drive
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 2)
CONDITIONS
q
MIN
2.5
q
q
TYP
1
MAX
16.5
1.5
2.47
±10
±2.5
±10
±10
170
60
– 7.5
270
UNITS
V
mA
V
mV
µA
µA
µA
µA
mV
mV
µA
µA
mA
ON = High, TIMER = Low
V
CC
Low-to-High Transition
V
ON
= V
CC
or GND
V
FAULT
= 15V, Pull-Down Device Off
V
PGI
= V
CC
or GND
V
SENSE
= V
CC
or GND
Fast Comparator Trips
Slow Comparator Trips
Charge Pump On, V
GATE
≤
0.2V
ON Low
FAULT Latched and Circuit Breaker
Tripped or in UVLO, V
GATE
= 15V
V
GATE
– V
CC
(For V
CC
= 2.5V)
V
GATE
– V
CC
(For V
CC
= 2.7V)
V
GATE
– V
CC
(For V
CC
= 3.3V)
V
GATE
– V
CC
(For V
CC
= 5V)
V
GATE
– V
CC
(For V
CC
= 12V)
V
GATE
– V
CC
(For V
CC
= 15V), (Note 3)
2.13
2.34
110
±1
q
±0.1
±1
±1
q
q
q
q
130
40
– 12.5
130
150
50
– 10
200
50
I
GATEDOWN
Normal GATE Pull-Down Current
q
q
q
q
q
q
q
q
q
q
4.0
4.5
5.0
10
10
8
0.08
1.23
0.4
1.20
0.2
1.316
0.455
1.236
28
8
8
10
16
18
15
0.3
1.39
0.5
1.26
V
GATEOV
V
ONHI
V
ONLO
V
PGI
V
PGIHST
GATE Overvoltage Lockout Threshold
ON Threshold High
ON Threshold Low
Power Good Input Threshold
Power Good Input Hysterisis
2
U
V
V
V
V
V
V
V
V
V
V
mV
4212f
W
U
U
W W
W
LTC4212
ELECTRICAL CHARACTERISTICS
SYMBOL
V
PGFHI
V
PGFHST
V
PGTHI
V
PGTLO
V
PGT∆V
I
PGT
PARAMETER
Power Good Glitch Filter High Threshold
Power Good Glitch Filter Hysterisis
Power Good Timer High Threshold
Power Good Timer Low Threshold
Power Good Timer Delta Threshold
Power Good Timer Pin Current
(Note 4)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Note 2)
CONDITIONS
q
MIN
1.20
0.928
0.640
0.283
– 5.61
4.63
– 5.61
– 2.5
1.20
0.15
1.20
TYP
1.236
40
0.952
0.657
0.295
– 5.1
5.2
5
-5.1
5
–2
5
1.236
0.200
1.236
50
0.14
MAX
1.26
0.976
0.680
0.304
– 4.59
5.77
– 4.49
– 1.5
1.26
0.40
1.26
0.4
20
UNITS
V
mV
V
V
V
µA
µA
mA
µA
mA
µA
mA
V
V
V
mV
V
ms
µs
µs
q
q
q
Power Good Timer On, C
PGT
Charging, PGT = 0.65V
Power Good Timer On, C
PGT
Discharging, PGT = 0.95V
Power Good Timer Off, PGT = 1.5V
Power Good Glitch Filter On, C
PGF
Charging
Power Good Timer Off, PGF = 1.5V
Timer On, V
TIMER
= 1V
Timer Off, TIMER = 1.5V
TIMER Low to High
TIMER High to Low
Latched Off Threshold, FAULT High to Low
I
FAULT
= 1.6mA
C
PGT
=10nF, PGT = 0.1V to FAULT Low
End of 14th PGT Cycle
PGF > 1.26V
V
CB
= 0mV to 200mV Step
V
FAULT
= 5V to 0V
ON Low to FAULT High
ON Low to GATE Off
q
q
q
q
q
q
q
I
PGF
I
TMR
V
TMR
V
FAULT
V
FAULTHST
V
OLFAULT
t
TO
t
FAULTLO
t
FAULTVG
t
FAULTFC
t
FAULTSC
t
EXTFAULT
t
RESET
t
OFF
Power Good Glitch Filter Pin Current
TIMER Current
TIMER Threshold
FAULT Threshold
FAULT Threshold Hysteresis
Output Low Voltage
Power Good Time-Out
Power Good Input Low at Time-Out to
GATE Discharging
Valid Power Good Glitch to GATE
Discharging
FAST COMP Trip to GATE Discharging
FAULT Low to GATE Discharging
Circuit Breaker Reset Delay Time
Turn-Off Time
q
q
16.3
18.16
1
1.5
q
q
q
q
500
10
1
18
3
120
10
700
30
5
250
ns
µs
µs
µs
µs
SLOW COMP Trip to GATE Discharging V
CB
= 0mV to 100mV Step
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All current into device pins are positive; all current out of device
pins are negative; all voltages are referenced to ground unless otherwise
specified.
Note 3:
An internal clamp limits the GATE pin to a minimum of 10V above
V
CC
. Driving this pin to voltages beyond the clamp may damage the part. If
a lower GATE pin voltage is desired, use an external zener diode. The GATE
capacitance must be < 0.15µF at maximum V
CC
.
Note 4:
Guaranteed by design and not tested in production.
4212f
3
LTC4212
otherwise noted.
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are T
A
= 25°C. V
CC
= 5V, unless
Supply Current vs Supply Voltage
4.0
3.5
SUPPLY CURRENT (mA)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2
4
6 8 10 12 14 16 18 20
SUPPLY VOLTAGE (V)
4212 G01
UNDERVOLTAGE LOCKOUT THRESHOLD (V)
SUPPLY CURRENT (mA)
3.0
2.5
2.0
1.5
1.0
0.5
0
GATE Voltage vs Supply Voltage
30
25
GATE VOLTAGE (V)
GATE VOLTAGE (V)
V
GATE
– V
CC
(V)
20
15
10
5
0
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
V
GATE
– V
CC
vs Temperature
18
GATE OUTPUT SOURCE CURRENT (µA)
16
14
V
CC
= 12V
12
11
10
9
8
7
GATE OUTPUT SOURCE CURRENT (µA)
V
GATE
– V
CC
(V)
12
10
8
6
4
2
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
V
CC
= 3.3V
V
CC
= 15V
V
CC
= 5V
4
U W
4212 G06
Supply Current vs Temperature
4.0
2.5
Undervoltage Lockout
Threshold vs Temperature
2.4
RISING EDGE
2.3
FALLING EDGE
V
CC
= 16.5V
2.2
V
CC
= 5V
V
CC
= 2.5V
–25
75
0
25
50
TEMPERATURE (°C)
100
125
2.1
0
–50
2.0
–50
–25
0
50
75
25
TEMPERATURE (°C)
100
125
4212 G02
4212 G03
GATE Voltage vs Temperature
30
25
20
15
10
5
0
–50
V
CC
= 2.5V
V
CC
= 5V
V
CC
= 16.5V
18
16
14
12
10
8
6
4
2
0
V
GATE
– V
CC
vs Supply Voltage
–25
75
0
25
50
TEMPERATURE (°C)
100
125
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
4212 G07
4212 G08
GATE Output Source Current vs
Supply Voltage
13
13
12
11
GATE Output Source Current vs
Temperature
V
CC
= 16.5V
10
9
8
7
–50
V
CC
= 2.5V
V
CC
= 5V
0
2
4
6 8 10 12 14 16 18 20
SUPPLY VOLTAGE (V)
4212 G10
–25
0
50
75
25
TEMPERATURE (°C)
100
125
4212 G09
4212 G11
4212f
LTC4212
otherwise noted.
TYPICAL PERFOR A CE CHARACTERISTICS
Specifications are T
A
= 25°C. V
CC
= 5V, unless
Fast GATE Pull-Down Current vs
Supply Voltage
80
FAST GATE PULL-DOWN CURRENT (mA)
80
FAST GATE PULL-DOWN CURRENT (mA)
70
60
50
40
30
20
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
V
CB
(SLOW COMP) (mV)
V
CB
(FAST COMP) vs Supply
Voltage
170
165
26
24
V
CB
(FAST COMP) (mV)
160
155
150
145
140
135
130
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
SLOW COMP TRIPS TO GATE
DISCHARGING DELAY (µs)
22
20
18
16
14
12
10
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
SLOW COMP TRIPS TO GATE
DISCHARGING DELAY (µs)
FAST COMP Trips to GATE
Discharging Delay vs Supply
Voltage
600
V
CB
= 0mV TO 200mV STEP
500
700
600
FAST COMP TRIPS TO GATE
DISCHARGING DELAY (ns)
V
CC
= 3V
500
400
300
200
100
0
–50
V
CC
= 15V
V
CC
= 5V
V
CC
= 12V
V
CC
= 16.5V
400
300
200
100
0
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
POWER GOOD TIME-OUT (ms)
FAST COMP TRIPS TO GATE
DISCHARGING DELAY (ns)
U W
4212 G14
4212 G28
Fast GATE Pull-Down Current vs
Temperature
60
58
70
60
50
40
30
20
–50
56
54
52
50
48
46
44
42
40
–25
0
50
75
25
TEMPERATURE (°C)
100
125
V
CB
(SLOW COMP) vs Supply
Voltage
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
4212 G15
4212 G26
SLOW COMP Trips to GATE
Discharging Delay vs Supply
Voltage
26
24
22
20
18
16
14
12
SLOW COMP Trips to GATE
Discharging Delay vs Temperature
V
CC
= 12V
V
CC
= 15V
V
CC
= 16.5V
V
CC
= 5V
V
CC
= 3V
10
–50
–25
25
50
0
75
TEMPERATURE (°C)
100
125
4212 G30
4212 G31
FAST COMP Trips to GATE
Discharging Delay vs Temperature
V
CB
= 0mV TO 200mV STEP
21
20
19
18
17
16
15
Power Good Timeout vs Supply
Voltage
–25
25
50
0
75
TEMPERATURE (°C)
100
125
0
2
4
6
8 10 12 14
SUPPLY VOLTAGE (V)
16
18
4212 G32
4212 G33
4212 G40
4212f
5
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