Typical Operating Circuit
N
M1
MAX4271
MAX4272
V
OUT
C
BOARD
CTIM
CSPD
C
TIM
ON
ON
GND
STAT
V
CC
R
SENSE
STAT
REMOVABLE CARD
2.7V TO 13.2V
BACKPLANE
IN
SENSE
GATE
GND
General Description
The MAX4271/MAX4272/MAX4273 comprise a com-
plete family of integrated 3V to 12V hot-swap con-
trollers. They allow the safe insertion and removal of
circuit cards into live backplanes.
The discharged filter capacitors of the circuit card pro-
vide a low impedance to the live backplane. High in-
rush currents from the backplane to the circuit card can
burn up connectors and components, or momentarily
collapse the backplane power supply leading to a sys-
tem reset. This family of hot-swap controllers prevents
such problems by regulating the current to a preset
limit when the board is plugged in, allowing the system
to stabilize safely. After the startup cycle is completed,
two on-chip comparators provide DualSpeed/BiLevelTM
protection against short circuits, load glitches, and
overcurrent conditions. In the event of a fault condition,
the load is disconnected. Fault recovery is handled by
unlatching (MAX4271), autoretry (MAX4272), or pro-
grammed (MAX4273) methods.
The MAX4271 family includes many integrated features
that reduce component count and design time. An on-
board charge pump provides the gate drive for a low-
cost, external N-FET. Integrated features like startup
current regulation and current glitch protection eliminate
external timing resistors and capacitors. Also featured
are an open-drain status output to indicate a fault condi-
tion, and an adjustable overcurrent response time.
The MAX4271 (latched fault protection) and MAX4272
(autoretry fault protection) come in 8-pin SO packages.
The MAX4273 (full function) comes in the space-saving
16-pin QSOP package and 16-pin SO package. All
parts are specified across the extended temperature
range, and have an absolute maximum rating of 15V to
provide extra protection against inductive kickback dur-
ing board removal.
Features
o Provide Safe Hot Swap for +3V to +12V Power
Supplies with Few External Components
o Unique Current Regulation Architecture
Minimizes N-FET Linear Mode Duration
o Autoretry Feature (MAX4272/MAX4273)
o DualSpeed/BiLevel Current Limit Protects Against
Current Glitches and Short Circuits
o Power-On RESET (MAX4273)
o 15V Absolute Maximum Rating Protects Against
Inductive Kickbacks During Board Removal
o Internal Charge Pump Generates Gate Drive for
External N-MOSFET
o Status Output Pin Indicates Fault/Safe Condition
o Space-Saving 8-Pin SO, 16-Pin QSOP Packages
________________________Applications
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
________________________________________________________________ Maxim Integrated Products
1
19-1694; Rev 1a; 4/01
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
EVALUATION KIT
AVAILABLE
DualSpeed/BiLevel is a trademark of Maxim Integrated
Products.
Pin Configurations appear at end of data sheet.
Base Stations
RAID
Remote-Access Servers
Network Routers and
Switches
ISDN
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
M A X 4 2 7 1ESA
-40
C to +85C
8 SO
M A X 4 2 7 2ESA
-40
C to +85C
8 SO
M A X 4 2 7 3EEE
-40
C to +85C
16 QSOP
MAX4273ESE
-40
C to +85C
16 SO
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= +2.7V to +13.2V, T
A
= -40C to +85C, unless otherwise noted. Typical values are at V
IN
= +5V and T
A
= +25C.) (Note 3)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note 1: GATE can be pulled below LLMON, but current must be limited to 2mA.
Note 2: INC and ON can be pulled below ground. Limiting the current to 2mA ensures that these pins are never lower than about -0.8V.
IN to GND ............................................................................+15V
STAT, OUTC, LLMON, AUXVCC to GND ...............-0.3V to +14V
GATE to GND ..............................................-0.3V to (V
IN
+ 8.5V)
GATE to LLMON (Note 1).........................................-1V to +8.5V
INC, ON to GND (Note 2) .........................................-1V to +14V
CEXT to GND ...............................................-8.5V to (V
IN
+ 0.3V)
CSPD, CTON,
REF to GND ...........-0.3V to the lower of (V
IN
+ 0.3V) or +12V
VSENSE, RTH, CTIM to GND.......................-0.3V to (V
IN
+ 0.3V)
Current into INC, ON (Note 2) ............................................2mA
Current into Any Other Pin ...............................................50mA
Continuous Power Dissipation (T
A
= +70C)
8-Pin SO (derate 5.9mW/C above +70C)..................471mW
16-Pin QSOP (derate 8.3mW/C above +70C)...........667mW
16-Pin SO (derate 8.7mW/C above +70C)................696mW
Operating Temperature Range ...........................-40C to +85C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLIES
Input Voltage Range
V
IN
2.7
13.2
V
Supply Current
I
Q
V
ON
= V
IN
0.6
1
mA
CURRENT CONTROL
T
A
= +25
C
45
50
55
Slow Comparator Threshold
V
SC,TH
V
IN
- V
SENSE
T
A
= T
MIN
to T
MAX
43.5
56
mV
C
SPD
= floating
10
20
40
s
Slow Comparator Response
Time
t
CSPD
C
SPD
= 100nF to GND
10
20
40
ms
T
A
= +25
C
45
50
55
5k
on
RTH to
V
IN
T
A
= T
MIN
to T
MAX
43.5
56
T
A
= +25
C
675
750
825
75k
on RTH
to V
IN
T
A
= T
MIN
to T
MAX
650
840
MAX4273
only
RTH = GN D
Fast Comparator Threshold
V
FC,TH
MAX4271/MAX4272
180
200
220
mV
Fast Comparator Response
Time
t
FCD
10mV overdrive, from overload condition to
gate discharging
350
ns
SENSE Input Bias Current
I
B,SENSE
V
SENSE
= V
IN
0.2
10
A
MOSFET DRIVER
MAX4271/MAX4272 C
TIM
= 100nF
21
31
41
MAX4273 C
TON
= 100nF
21
31
41
ms
Startup Period
(Notes 4, 5)
t
START
No capacitor
5.5
s
Gate Charge Current
I
GATE
GATE = IN (Note 6)
100
A
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +2.7V to +13.2V, T
A
= -40C to +85C, unless otherwise noted. Typical values are at V
IN
= +5V and T
A
= +25C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Slow Turn-Off Time
t
SLOW,OFF
Time from trigger to V
GATE
< 0.1V
(triggered by either the ON input or the
slow comparator), C
GATE
= 1000pF to
GND
60
s
Fast Turn-Off Time
t
FAST,OFF
Time from current overload to V
GATE
< 0.1V
(triggered by the fast comparator, during
normal operation), C
GATE
= 1000pF to GND
15
s
Maximum Gate Protection
Voltage
Voltage at which internal zener clamp
circuitry is triggered, measured with
respect to V
IN
(MAX4271/MAX4272),
measured with respect to V
LLMON
(MAX4273)
6.7
7.5
V
V
IN
5V
5
Minimum Gate Drive Voltage
Measured with
respect to V
IN,
I
GATE
= 8.5A
V
IN
2.7V
2.7
V
During fast discharge, due to a fast
comparator fault in normal operation
0.4
1
2.75
mA
During startup (current regulation provided
by fast comparator)
25
70
195
Gate Discharge Current
I
GATE,DIS
During normal discharge, due to a slow
comparator fault in normal mode, or by ON
going low
75
200
550
A
LLMON Overvoltage Threshold
Startup is initiated only after V
LLMON
is less
than this voltage (MAX4273)
0.1
V
GATE Overvoltage Threshold
Startup is initiated only after V
GATE
is less
than this voltage
0.1
0.6
V
LLMON Impedance
Im p ed ance to GN D , after a faul t ( M AX 4273) 1
k
REFERENCE (MAX4273)
Output Voltage
V
REF
No load, V
IN
= 5V
1.164
1.2
1.236
V
Line Regulation
V
REF, LINE
2.7V
V
IN
13.2V, no load
1
8
mV
Load Regulation
V
REF,
LOAD
I
REF
= 0 to 100
A, V
IN
= 5V
0.6
3
mV
ON AND RESET COMPARATORS
Threshold Voltage
V
IN
= 5V, rising threshold at ON or INC
0.575
0.6
0.625
V
Hysteresis
V
HYST
3
mV
Power-Supply Rejection Ratio
PSRR
2.7V
V
IN
13.2V
1
mV/V
10mV overdrive, ON going positive or
negative, INC going negative
10
s
Propagation Delay
t
D,COMP
INC going positive
100
150
200
ms
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
4
_______________________________________________________________________________________
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range
Input can be driven to the absolute
maximum limit without false output
inversion
-0.1
13.2
V
Input Bias Current
I
B,COMP
0.001
1
A
ON Pulse Width Low (Note 7)
t
RESTART
To unlatch a fault MAX4271, MAX4273 with
C
TIM
= IN
20
s
DIGITAL OUTPUTS (STAT, OUTC)
Output Leakage Current
V
STAT
13.2, V
OUTC
13.2
1
A
Output Voltage Low
V
OL
I
SINK
= 1mA
0.4
V
RETRY TIMING (MAX4272, MAX4273)
Retry Timeout Period
t
RETRY
100nF capacitor on C
TIM
(Note 5)
0.5
1
2
s
Default Retry
Timeout Period
t
RETRY
(default)
C
TIM
= no connection
176
s
UNDERVOLTAGE LOCKOUT (UVLO)
Threshold
V
UVLO
Startup is initiated when this threshold is
exceeded at IN
2.25
2.67
V
Hysteresis
V
U V LO,H YS T
100
mV
Delay
t
D,UVLO
Time the input voltage must exceed
undervoltage lockout before startup is
initiated
100
150
200
ms
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +2.7V to +13.2V, T
A
= -40C to +85C, unless otherwise noted. Typical values are at V
IN
= +5V and T
A
= +25C.) (Note 3)
Note 3: All devices are 100% tested at T
A
= +25C. All temperature limits are guaranteed by design.
Note 4: Startup period is the time during which the slow comparator is ignored and the fast comparator regulates the sense current.
It is measured from the time ON is brought high.
Note 5: Inferred from test with C
TIM
= 1nF.
Note 6: The current available at GATE is a function of V
GATE
(see Typical Operating Characteristics).
Note 7: Guaranteed by design.
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
_______________________________________________________________________________________
5
Typical Operating Characteristics
(V
IN
= 5V, R
SENSE
= 100m
, C
BOARD
= 47F, T
A
= +25C, unless otherwise noted.)
0
0.3
0.2
0.1
0.5
0.4
0.9
0.8
0.7
0.6
1.0
0
2
4
6
8
10
12
14
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX4271/3-01
V
IN
(V)
SUPPLY CURRENT (mA)
ON = V
IN
I
GATE
= 10
A
ON = GND
-40
-15
10
35
60
85
SUPPLY CURRENT vs. TEMPERATURE
MAX4271/3-02
TEMPERATURE (
C)
0
0.3
0.2
0.1
0.5
0.4
0.9
0.8
0.7
0.6
1.0
SUPPLY CURRENT (mA)
ON = V
IN
V
IN
= 12V
V
IN
= 5V
V
IN
= 3V
180
200
190
220
210
230
240
18
20
19
22
21
23
24
0
6
8
2
4
10
12
14
SLOW COMPARATOR
RESPONSE TIME vs. INPUT VOLTAGE
MAX4271/3-03
V
IN
(V)
t
CSPD
(
s)
t
CSPD
(ms)
CSPD = 110nF
TIME IN ms
CSPD = 0
TIME IN
s
49.0
49.6
49.4
49.2
50.0
49.8
50.8
50.6
50.4
50.2
51.0
0
2
4
6
8
10
12
14
SLOW COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
MAX4271/3-04
V
IN
(V)
V
SC,TH
(mV)
T
A
= -40
C
T
A
= +25
C
T
A
= +85
C
200
250
350
300
400
450
1
10
100
1000
FAST COMPARATOR RESPONSE TIME
vs. OVERDRIVE VOLTAGE
MAX4271/3-05
OVERDRIVE VOLTAGE (mV)
RESPONSE TIME (ns)
V
IN
= 12V
V
IN
= 5V
V
IN
= 3V
200
300
400
350
450
500
-40
10
-15
35
60
85
FAST COMPARATOR RESPONSE TIME
vs. TEMPERATURE
MAX4271/3-06
TEMPERATURE (
C)
RESPONSE TIME (ns)
V
IN
= 12V
V
IN
= 5V
V
IN
= 3V
250
190
196
194
192
200
198
208
206
204
202
210
FAST COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
MAX4271/3-07
V
FC,TH
(mV)
0
2
4
6
8
10
12
14
V
IN
(V)
T
A
= -40
C
T
A
= +25
C
T
A
= +85
C
0.1
1
1k
100
10
10k
100k
0.01
1
0.1
10
100
1000
TIME TO FAST DISCHARGE GATE
vs. C
GATE
MAX4271/3-08
C
GATE
(nF)
TIME TO DISCHARGE GATE (
s)
V
IN
= 12V
V
IN
= 5V
V
IN
= 3V
NO EXTERNAL MOSFET
DISCHARGE TO V
GATE
= 0.1V
250
270
310
290
330
350
0
4
2
6
8
10
12
14
STARTUP PERIOD
vs. INPUT VOLTAGE
MAX4271/3-09
V
IN
(V)
t
START
(
s)
25
27
31
29
33
35
t
START
(ms)
C
TIM
= 100nF
TIME IN ms
C
TIM
= 1nF
TIME IN
s
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