NOT RECOMMENDED FOR NEW DESIGNS
Please See LTC4253B for Drop-In Replacement
LTC4253/LTC4253A
–48V Hot Swap Controllers
with Sequencer
DESCRIPTION
The LTC
®
4253/LTC4253A negative voltage Hot Swap™
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 condi-
tions. The LTC4253/LTC4253A latch off after a circuit fault.
Adjustable undervoltage and overvoltage detectors dis-
connect 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 circuit 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
.
FEATURES
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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
APPLICATIONS
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–48V Distributed Power Systems
Negative Power Supply Control
Central Office Switching
High Availability Servers
Disk Arrays
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot
Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of
their respective owners.
TYPICAL APPLICATION
– 48V/2.5A Hot Swap Controller
– 48V RTN
1μF
– 48V RTN
402k
1%
5.6k
10nF
EN2 EN3 V
IN
D
IN††
LTC4253
DDZ13B*
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
*DIODES, INC.
†
MOC207
††
RECOMMENDED FOR HARSH ENVIRONMENTS.
V
OUT
50V
1ms/DIV
4253 TA01b
2.5k
15k(1/4W)/6
Start-Up Behavior
V
IN
5.6k
+
100μF
5.6k
LOAD1
LOAD2
EN
EN
EN
SS
1V
LOAD3
GATE
10V
†
†
†
4253 TA01
SENSE
50mV
425353afe
1
LTC4253/LTC4253A
ABSOLUTE MAXIMUM RATINGS
(Note 1), All voltages referred to V
EE
PIN CONFIGURATION
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
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 ................................................ 0°C to 70°C
LTC4253I .............................................–40°C to 85°C
LTC4253AC
(OBSOLETE)
......................... 0°C to 70°C
LTC4253AI
(OBSOLETE)
......................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC4253CGN#PBF
LTC4253IGN#PBF
LTC4253ACGN#PBF
LTC4253AIGN#PBF
TAPE AND REEL
LTC4253CGN#TRPBF
LTC4253IGN#TRPBF
LTC4253ACGN#TRPBF
LTC4253AIGN#TRPBF
PART MARKING
4253
4253I
4253A
4253AI
PACKAGE DESCRIPTION
16-Lead Plastic SSOP
16-Lead Plastic SSOP
OBSOLETE PACKAGE
16-Lead Plastic SSOP
16-Lead Plastic SSOP
0°C to 70°C
–40°C to 85°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
425353afe
2
LTC4253/LTC4253A
ELECTRICAL CHARACTERISTICS
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
)
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)
R
SS
V
OS
SS Output Impedance
Analog Current Limit Offset Voltage
●
●
●
●
●
●
●
●
●
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
LTC4253
CONDITIONS
I
IN
= 2mA
I
IN
= (2mA to 30mA)
UV = OV = 4V, V
IN
= (V
Z
– 0.3V)
Coming Out of UVLO (Rising V
IN
)
●
●
●
●
●
●
LTC4253A
MAX
14.5
2
11.5
1.5
0.8
0.25
2
0.8
600
±10
180
±10
60
120
1.05
1.20
200
1.4
28
28
50
10
0.05
70
30
50
17
190
V
Z
10
12
0.5
2.8
V
Z
70
1.38
300
1.55
40
60
45
±0.1
120
±0.1
50
±10
180
±10
55
MIN
11.5
TYP
13
5
1.1
9
0.5
2
10
0.75
MAX UNITS
14.5
V
Ω
mA
V
V
V
V
mV
μA
μA
μA
mV
mV
V/V
mV
V
μA
mA
kΩ
mV
V/V
μA
mA
mA
V
V
V
V
V
3.05
3.08
324
3.11
356
V
mV
mV
V
V
425353afe
MIN
11.5
TYP
13
5
0.8
9.2
0.5
2
1
600
±0.1
60
40
80
120
±0.1
50
100
150
2
12
200
2.2
22
28
100
10
0.05
300
2.4
32
150
1.25
16
V
ACL
+ V
OS
Ratio (V
ACL
+ V
OS
) to SS Voltage
V
SS
I
GATE
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
External MOSFET Gate Drive
Gate Low Threshold
Gate High Threshold
UV Pin Threshold HIGH
UV Pin Threshold LOW
UV Pin Threshold
UV Pin Hysteresis
●
●
30
50
17
190
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
●
3.075 3.225 3.375
●
2.775 2.925 3.075
●
230
OV Low to High
OV High to Low
●
●
300
6.15
5.85
350
292
6.45
6.15
OV Pin Threshold HIGH
OV Pin Threshold LOW
5.85
5.55
3
LTC4253/LTC4253A
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OV
V
OVHST
I
SENSE
I
INP
V
TMRH
V
TMRL
I
TMR
PARAMETER
OV Pin Threshold
OV Pin Hysteresis
●
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
LTC4253
CONDITIONS
OV Low to High
●
LTC4253A
MAX
350
82
102
15
±0.1
3.5
0.8
3
4
1
5
28
280
120
200
600
7
9
4.5
7
3
7
3.5
3
5
8
4
0.33
5
28
3
±1
± 0.1
±1
7.5
0.4
1.2
70
8.5
0.4
1.2
70
30
5
6
0.25
50
250
2
2.39
3
7
7
9
4.5
280
122
30
±1
4.5
1.2
7
30
±1
4.5
1.2
7
MIN
5.04
TYP
5.09
MAX UNITS
5.14
V
mV
mV
μA
μA
V
V
μA
mA
μA
μA
μA
μA/μA
V
V
μA
mA
V
μA
μA
V
V
V
μA
μs
μs
μs
5
5
μs
μs
MIN
230
TYP
300
15
± 0.1
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
●
●
●
●
●
3.5
0.8
3
4
1
5
28
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
3
5
8
4
0.33
5
28
ΔI
TMRACC
ΔI
DRN
V
SQTMRH
V
SQTMRL
I
SQTMR
I
TMR
at I
DRN
= 50μA – I
TMR
at I
DRN
= 0μA Timer On (Circuit Breaker with
50μA
I
DRN
= 50μA)
SQTIMER Pin Voltage High Threshold
SQTIMER Pin Voltage Low Threshold
SQTIMER Pin Current
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
●
2
2.39
± 0.1
●
●
●
●
6
7
0.25
30
50
250
250
140
●
●
0.4
0.4
5
5
0.4
0.4
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.
425353afe
4
LTC4253/LTC4253A
TYPICAL PERFORMANCE CHARACTERISTICS
V
Z
vs Temperature
14.5
I
IN
= 2mA
1000
I
IN
vs V
IN
1000
950
I
IN
vs Temperature
V
IN
= V
Z
– 0.3V
14.0
100
T
A
= –40°C
I
IN
(mA)
13.5
V
Z
(V)
T
A
= 25°C
10
T
A
= 85°C
I
IN
(μA)
T
A
= 125°C
900
850
800
750
700
13.0
12.5
1
650
600
550
12.0
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G01
0.1
0
5
10
V
IN
(V)
15
20
4253 G02
500
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G03
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
V
CB
(mV)
I
EN
(μA)
55
54
53
52
Circuit Breaker Current Limit
Voltage V
CB
vs Temperature
150
140
130
120
V
ACL
(mV)
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
110
100
90
80
70
60
50
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G06
4253 G04
Fast Current Limit Voltage V
FCL
vs
Temperature
300
280
260
240
V
FCL
(mV)
I
GATE
(μA)
220
200
180
160
140
120
100
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G07
I
GATE
(Source) vs Temperature
60
58
56
54
I
GATE
(mA)
52
50
48
46
44
42
40
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G08
I
GATE
(ACL, Sink) vs Temperature
30
25
20
15
10
5
0
–55 –35 –15
UV/OV = 4V
TIMER = 0V
V
SENSE
– V
EE
= 0.15V
V
GATE
= 3V
UV/OV = 4V
TIMER = 0V
V
SENSE
= V
EE
V
GATE
= 0V
5 25 45 65 85 105 125
TEMPERATURE (°C)
4253 G09
425353afe
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