FEATURES
■
■
■
■
■
■
■
■
■
■
LTC4253/LTC4253A
– 48V Hot Swap Controllers
with Sequencer
DESCRIPTIO
The LTC
®
4253/LTC4253A negative voltage Hot Swap
TM
controllers allow 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. The
LTC4253/LTC4253A latch off after a circuit fault.
Adjustable undervoltage and overvoltage detectors discon-
nect the load whenever the input supply exceeds the desired
operating range. The LTC4253/LTC4253A’s supply input
is shunt-regulated, allowing safe operation with very high
supply voltages. A multifunction timer delays initial start-
up and controls the circuit breaker’s response time. The cir-
cuit breaker’s response time can be accelerated by sensing
excessive MOSFET drain voltage, keeping the MOSFET
within its safe operating area (SOA). An adjustable soft-start
circuit controls MOSFET inrush current at start-up.
Three power good outputs are sequenced by an adjustable
timer and two ENABLE inputs to enable external power
modules at start-up or disable them if the circuit breaker
trips. The LTC4253A features tight
±1%
undervoltage/
overvoltage threshold accuracy. The LTC4253/LTC4253A
are available in a 16-pin SSOP.
Allows Safe Board Insertion and Removal from a
Live – 48V Backplane
Floating Topology Permits Very High Voltage
Operation
Adjustable Analog Current Limit with Breaker Timer
Ideal for Two Battery Feeds
Fast Response Time Limits Peak Fault Current
Adjustable Undervoltage/Overvoltage Protection
with
±1%
Threshold Accuracy (LTC4253A)
Three Sequenced Power Good Outputs
Adjustable Soft-Start Current Limit
Adjustable Timer with Drain Voltage Accelerated
Response
Latchoff After Fault
Available in a 16-Pin SSOP Package
APPLICATIO S
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■
■
■
■
– 48V Distributed Power Systems
Negative Power Supply Control
Central Office Switching
High Availability Servers
Disk Arrays
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
– 48V RTN
1µF
– 48V RTN
402k
1%
– 48V/2.5A Hot Swap Controller
2.5k
15k(1/4W)/6
5.6k
10nF
EN2 EN3 V
IN
LTC4253
RESET
UV
OV
32.4k
1%
68nF
0.1µF
– 48V A
B3100*
0.33µF
SS
SQTIMER
GATE
TIMER
V
EE
– 48V B
B3100*
SENSE
10Ω
18nF
0.02Ω
PWRGD1
PWRGD2
PWRGD3
DRAIN
1M
IRF530S
†
MOC207
†
†
†
V
IN
5.6k
+
100µF
5.6k
LOAD1
LOAD2
EN
EN
EN
LOAD3
4253 TA01
*DIODES, INC.
U
U
U
Start-Up Behavior
GATE
10V
SS
1V
SENSE
50mV
V
OUT
50V
1ms/DIV
4253 TA01b
425353afc
1
LTC4253/LTC4253A
ABSOLUTE
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
EN2
PWRGD2
PWRGD1
V
IN
RESET
SS
SENSE
V
EE
1
2
3
4
5
6
7
8
16 PWRGD3
15 EN3
14 SQTIMER
13 TIMER
12 UV
11 OV
10 DRAIN
9
GATE
(Note 1), All voltages referred to V
EE
Current into V
IN
(100µs Pulse) ........................... 100mA
Current into DRAIN (100µs Pulse) ........................ 20mA
V
IN
, DRAIN Minimum Voltage............................... – 0.3V
Input/Output (Except SENSE
and DRAIN) Voltage ...................................– 0.3V to 16V
SENSE Voltage ..........................................– 0.6V to 16V
Current Out of SENSE (20µs Pulse) .................. – 200mA
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range
LTC4253C/LTC4253AC ............................ 0°C to 70°C
LTC4253I/LTC4253AI ......................... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC4253CGN
LTC4253IGN
LTC4253ACGN
LTC4253AIGN
GN PART
MARKING
4253
4253I
4253A
4253AI
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
SYMBOL
V
Z
R
Z
I
IN
V
LKO
V
LKH
V
IH
V
IL
V
HYST
I
RESET
I
EN
V
CB
V
ACL
V
ACL
V
CB
V
FCL
V
SS
I
SS
PARAMETER
V
IN
– V
EE
Zener Voltage
V
IN
– V
EE
Zener Dynamic Impedance
V
IN
Supply Current
V
IN
Undervoltage Lockout
V
IN
Undervoltage Lockout Hysteresis
TTL Input High Voltage
TTL Input Low Voltage
TTL Input Buffer Hysteresis
RESET Input Current
EN2, EN3 Input Current
Circuit Breaker Current Limit Voltage
Analog Current Limit Voltage
Analog Current Limit Voltage
Circuit Breaker Current Limit Voltage
Fast Current Limit Voltage
SS Voltage
SS Pin Current
V
EE
≤
V
RESET
≤
V
IN
V
EN
= 4V
V
EN
= 0V
V
CB
= (V
SENSE
– V
EE
)
●
●
●
●
ELECTRICAL CHARACTERISTICS
I
IN
= 2mA
CONDITIONS
●
●
●
●
●
●
LTC4253
MIN TYP MAX
11.5
13
5
0.8
9.2
0.5
2
0.8
600
±0.1
60
40
80
120
±0.1
50
100
±10
180
±10
60
120
1
2
11.5
1.5
14.5
LTC4253A
MIN TYP MAX
11.5
13
5
1.1
9
0.25
2
0.8
600
±0.1
60
45
1.05
120
±0.1
50
1.20
200
1.4
28
28
±10
180
±10
55
1.38
300
1.55
40
0.5
2
10
0.75
14.5
UNITS
V
Ω
mA
V
V
V
V
mV
µA
µA
µA
mV
mV
V/V
mV
V
µA
mA
425353afc
I
IN
= (2mA to 30mA)
UV = OV = 4V, V
IN
= (V
Z
– 0.3V)
Coming Out of UVLO (Rising V
IN
)
V
ACL
= (V
SENSE
– V
EE
), SS = Open or 2.2V
●
V
ACL
= (V
SENSE
– V
EE
), SS = Open or 1.4V
●
V
FCL
= (V
SENSE
– V
EE
)
After End of SS Timing Cycle
UV = OV = 4V, V
SENSE
= V
EE,
V
SS
= 0V (Sourcing)
UV = OV = 0V, V
SENSE
= V
EE,
V
SS
= 1V (Sinking)
●
●
●
150
2
12
200
2.2
22
28
300
2.4
32
150
1.25
16
2
U
W
U
U
W W
W
LTC4253/LTC4253A
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
SYMBOL
R
SS
V
OS
V
ACL
+ V
OS
V
SS
I
GATE
PARAMETER
SS Output Impedance
Analog Current Limit Offset Voltage
Ratio (V
ACL
+ V
OS
) to SS Voltage
GATE Pin Output Current
UV = OV = 4V, V
SENSE
= V
EE
,
V
GATE
= 0V (Sourcing)
UV = OV = 4V, V
SENSE
– V
EE
= 0.15V,
V
GATE
= 3V (Sinking)
UV = OV = 4V, V
SENSE
– V
EE
= 0.3V,
V
GATE
= 1V (Sinking)
V
GATE
V
GATEL
V
GATEH
V
UVHI
V
UVLO
V
UV
V
UVHST
V
OVHI
V
OVLO
V
OV
V
OVHST
I
SENSE
I
INP
V
TMRH
V
TMRL
I
TMR
External MOSFET Gate Drive
Gate Low Threshold
Gate High Threshold
UV Pin Threshold HIGH
UV Pin Threshold LOW
UV Pin Threshold
UV Pin Hysteresis
●
●
ELECTRICAL CHARACTERISTICS
CONDITIONS
LTC4253
MIN TYP MAX
100
10
0.05
30
50
17
190
●
LTC4253A
MIN TYP MAX
50
10
0.05
UNITS
kΩ
mV
V/V
70
30
50
17
190
70
µA
mA
mA
V
GATE
– V
EE,
I
IN
= 2mA
Before Gate Ramp Up
V
GATEH
= V
IN
– V
GATE
, for PWRGD1,
PWRGD2, PWRGD3 Status
UV Low to High
UV High to Low
UV Low to High
10
12
0.5
2.8
V
Z
10
12
0.5
2.8
V
Z
V
V
V
V
V
●
●
●
3.075 3.225 3.375
2.775 2.925 3.075
3.05
230
300
350
292
5.85 6.15
5.55 5.85
230
300
15
±0.1
3.5
0.8
3
4
1
5
28
6.45
6.15
5.04
350
82
30
±1
4.5
1.2
7
3.5
0.8
3
102
15
±0.1
4
1
5
28
280
120
200
600
7
9
4.5
3
7
3.5
5
8
4
0.33
7
9
4.5
280
122
30
±1
4.5
1.2
7
5.09
5.14
324
356
3.08
3.11
V
mV
mV
V
V
V
mV
mV
µA
µA
V
V
µA
mA
µA
µA
µA
µA/µA
V
V
OV Pin Threshold HIGH
OV Pin Threshold LOW
OV Pin Threshold
OV Pin Hysteresis
OV Low to High
OV High to Low
OV Low to High
●
●
●
●
SENSE Pin Input Current
UV, OV Pin Input Current
TIMER Pin Voltage High Threshold
TIMER Pin Voltage Low Threshold
TIMER Pin Current
UV = 0V = 4V, V
SENSE
= 50mV
(Sourcing)
UV = OV = 4V
●
●
●
●
Timer On (Initial Cycle/Latchoff,
Sourcing), V
TMR
= 2V
Timer Off (Initial Cycle, Sinking),
V
TMR
= 2V
Timer On (Circuit Breaker, Sourcing,
I
DRN
= 0µA), V
TMR
= 2V
Timer On (Circuit Breaker, Sourcing,
I
DRN
= 50µA), V
TMR
= 2V
Timer Off (Circuit Breaker, Sinking),
V
TMR
= 2V
●
●
120
200
600
●
●
●
3
7
3.5
5
8
4
0.33
∆I
TMRACC
∆I
DRN
V
SQTMRH
V
SQTMRL
I
TMR
at I
DRN
= 50µA – I
TMR
at I
DRN
= 0µA
50µA
SQTIMER Pin Voltage High Threshold
SQTIMER Pin Voltage Low Threshold
Timer On (Circuit Breaker with
I
DRN
= 50µA)
425353afc
3
LTC4253/LTC4253A
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
SYMBOL PARAMETER
I
SQTMR
SQTIMER Pin Current
CONDITIONS
SQTIMER On (Power Good
Sequence, Sourcing), V
SQTMR
= 2V
SQTIMER Off (Power Good
Sequence, Sinking), V
SQTMR
= 2V
V
DRNL
I
DRNL
V
DRNCL
V
PGL
I
PGH
t
SQ
t
SS
t
PLLUG
t
PHLOG
DRAIN Pin Voltage Low Threshold
DRAIN Leakage Current
DRAIN Pin Clamp Voltage
PWRGD1, PWRGD2, PWRGD3
Output Low Voltage
PWRGD1, PWRGD2, PWRGD3
Output High Current
SQTIMER Default Ramp Period
SS Default Ramp Period
UV Low to GATE Low
OV High to GATE Low
For PWRGD1, PWRGD2, PWRGD3 Status
V
DRAIN
= 5V
V
DRAIN
= 4V
I
DRN
= 50µA
I
PG
= 1.6mA
I
PG
= 5mA
V
PG
= 0V (Sourcing)
SQTIMER Pin Floating,
V
SQTMR
Ramps from 0.5V to 3.5V
SS Pin Floating, V
SS
Ramps from 0.2V to 2V
SS Pin Floating, V
SS
Ramps from 0.2V to 1.25V
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
LTC4253
MIN TYP MAX
3
5
28
2
2.39
±0.1
6
7
0.25
30
50
250
250
3
±1
8.5
0.4
1.2
70
7
LTC4253A
MIN TYP MAX
3
5
28
2
2.39
±0.1
5
6
0.25
30
50
250
3
±1
7.5
0.4
1.2
70
7
UNITS
µA
mA
V
µA
µA
V
V
V
µA
µs
µs
µs
140
0.4
0.4
5
5
0.4
0.4
5
5
µs
µs
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 V
EE
unless otherwise
specified.
TYPICAL PERFOR A CE CHARACTERISTICS
V
Z
vs Temperature
14.5
I
IN
= 2mA
1000
14.0
100
T
A
= –40°C
I
IN
(mA)
I
IN
(µA)
13.5
V
Z
(V)
13.0
12.5
12.0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G01
4
U W
I
IN
vs V
IN
1000
950
900
T
A
= 85°C
T
A
= 125°C
850
800
750
700
650
1
600
550
0.1
0
5
10
V
IN
(V)
15
20
4253 G02
I
IN
vs Temperature
V
IN
= V
Z
– 0.3V
T
A
= 25°C
10
500
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G03
425353afc
LTC4253/LTC4253A
TYPICAL PERFOR A CE CHARACTERISTICS
I
EN
vs V
EN
180
I
IN
= 2mA
160 T
A
= 25°C
140
120
100
80
60
40
20
0
0
2
4
6
8
10
V
EN
(V)
12
14
16
55
54
53
52
V
ACL
(mV)
V
CB
(mV)
I
EN
(µA)
Fast Current Limit Voltage V
FCL
vs
Temperature
300
280
260
240
I
GATE
(µA)
200
180
160
140
120
100
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G07
50
48
46
44
42
40
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G08
I
GATE
(mA)
V
FCL
(mV)
220
I
GATE
(FCL, Sink) vs Temperature
400
350
300
I
GATE
(mA)
250
200
150
100
50
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G10
UV/OV = 4V
TIMER = 0V
V
SENSE
– V
EE
= 0.3V
V
GATE
= 1V
12.5
12.0
11.5
11.0
10.5
10.0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G11
V
GATEL
(V)
V
GATE
(V)
U W
4253 G04
Circuit Breaker Current Limit
Voltage V
CB
vs Temperature
150
140
130
120
110
100
90
80
70
60
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G05
Analog Current Limit Voltage V
ACL
vs Temperature
51
50
49
48
47
46
45
–55 –35 –15
50
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G06
I
GATE
(Source) vs Temperature
60
58
56
54
52
UV/OV = 4V
TIMER = 0V
V
SENSE
= V
EE
V
GATE
= 0V
30
25
20
15
10
5
I
GATE
(ACL, Sink) vs Temperature
UV/OV = 4V
TIMER = 0V
V
SENSE
– V
EE
= 0.15V
V
GATE
= 3V
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G09
V
GATE
vs Temperature
14.5
14.0
13.5
13.0
UV/OV = 4V
TIMER = 0V
V
SENSE
= V
EE
I
IN
= 2mA
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
V
GATEL
vs Temperature
UV/OV = 4V
TIMER = 0V
GATE THRESHOLD
BEFORE RAMP UP
0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G12
425353afc
5
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