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19-1694; Rev 2; 12/07
EVAALVUAAILTAIOBNLEKIT
3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
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/BiLevel™
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.
DualSpeed/BiLevel is a trademark of Maxim Integrated
Products.
Features
Provide Safe Hot Swap for +3V to +12V Power
Supplies with Few External Components
Unique Current Regulation Architecture
Minimizes n-FET Linear Mode Duration
Autoretry Feature (MAX4272/MAX4273)
DualSpeed/BiLevel Current Limit Protects Against
Current Glitches and Short Circuits
Power-On RESET (MAX4273)
15V Absolute Maximum Rating Protects Against
Inductive Kickbacks During Board Removal
Internal Charge Pump Generates Gate Drive for
External n-MOSFET
Status Output Pin Indicates Fault/Safe Condition
Space-Saving 8-Pin SO, 16-Pin QSOP Packages
________________________Applications
Base Stations
RAID
Remote-Access Servers
Network Routers and
Switches
ISDN
PART
MAX4271ESA
MAX4272ESA
MAX4273EEE
MAX4273ESE
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8 SO
8 SO
16 QSOP
16 SO
PKG
CODE
S8-1
S8-1
E16-1
E16-1
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
BACKPLANE
VCC
REMOVABLE CARD
2.7V TO 13.2V
RSENSE
M1
N
STAT
GND
ON
IN
STAT
ON
SENSE
GATE
MAX4271
MAX4272
GND
CSPD
CTIM
VOUT
CBOARD
CTIM
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

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3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
ABSOLUTE MAXIMUM RATINGS
IN to GND ............................................................................+15V
STAT, OUTC, LLMON, AUXVCC to GND ...............-0.3V to +14V
GATE to GND ..............................................-0.3V to (VIN + 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 (VIN + 0.3V)
CSPD, CTON,
REF to GND ...........-0.3V to the lower of (VIN + 0.3V) or +12V
VSENSE, RTH, CTIM to GND.......................-0.3V to (VIN + 0.3V)
Current into INC, ON (Note 2) ............................................±2mA
Current into Any Other Pin ...............................................±50mA
Continuous Power Dissipation (TA = +70°C)
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
16-Pin SO (derate 8.7mW/°C above +70°C)................696mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
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.
ELECTRICAL CHARACTERISTICS
(VIN = +2.7V to +13.2V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = +5V and TA = +25°C.) (Note 3)
PARAMETER
POWER SUPPLIES
Input Voltage Range
Supply Current
CURRENT CONTROL
Slow Comparator Threshold
Slow Comparator Response
Time
Fast Comparator Threshold
SYMBOL
CONDITIONS
MIN TYP MAX UNITS
VIN
IQ VON = VIN
2.7 13.2 V
0.6 1 mA
VSC,TH VIN - VSENSE
TA = +25°C
45 50 55
mV
TA = TMIN to TMAX
43.5
56
tCSPD
CSPD = floating
CSPD = 100nF to GND
10 20 40 μs
10 20 40 ms
5kΩ on TA = +25°C
45 50 55
RTH to
VIN
TA = TMIN to TMAX
43.5
56
VFC,TH
MAX4273
only 75kΩ
on RTH
TA = +25°C
675 750 825 mV
to VIN
TA = TMIN to TMAX
650
840
RTH = GND
MAX4271/MAX4272
180 200 220
Fast Comparator Response
Time
SENSE Input Bias Current
MOSFET DRIVER
Startup Period
(Notes 4, 5)
Gate Charge Current
tFCD
IB,SENSE
10mV overdrive, from overload condition to
gate discharging
VSENSE = VIN
350
0.2 10
ns
μA
tSTART
IGATE
MAX4271/MAX4272 CTIM = 100nF
MAX4273 CTON = 100nF
No capacitor
GATE = IN (Note 6)
21 31 41
ms
21 31 41
5.5 μs
100 μA
2 _______________________________________________________________________________________

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3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +2.7V to +13.2V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = +5V and TA = +25°C.) (Note 3)
PARAMETER
Slow Turn-Off Time
SYMBOL
tSLOW,OFF
CONDITIONS
Time from trigger to VGATE < 0.1V
(triggered by either the ON input or the
slow comparator), CGATE = 1000pF to
GND
MIN TYP MAX UNITS
60 µs
Fast Turn-Off Time
tFAST,OFF
Time from current overload to VGATE < 0.1V
(triggered by the fast comparator, during
normal operation), CGATE = 1000pF to GND
15
μs
Maximum Gate Protection
Voltage
Minimum Gate Drive Voltage
Voltage at which internal zener clamp
circuitry is triggered, measured with
respect to VIN (MAX4271/MAX4272),
measured with respect to VLLMON
(MAX4273)
Measured with
respect to VIN,
IGATE = 8.5µA
VIN 5V
VIN 2.7V
During fast discharge, due to a fast
comparator fault in normal operation
6.7 7.5
V
5
V
2.7
0.4 1 2.75 mA
Gate Discharge Current
IGATE,DIS
During startup (current regulation provided
by fast comparator)
During normal discharge, due to a slow
comparator fault in normal mode, or by ON
going low
25
75
70 195
200 550
μA
LLMON Overvoltage Threshold
Startup is initiated only after VLLMON is less
than this voltage (MAX4273)
0.1
V
GATE Overvoltage Threshold
Startup is initiated only after VGATE is less
than this voltage
LLMON Impedance
Impedance to GND, after a fault (MAX4273)
REFERENCE (MAX4273)
Output Voltage
Line Regulation
VREF No load, VIN = 5V
ΔVREF, LINE 2.7V VIN 13.2V, no load
Load Regulation
ΔVREF,
LOAD
ON AND RESET COMPARATORS
Threshold Voltage
Hysteresis
Power-Supply Rejection Ratio
VHYST
PSRR
IREF = 0 to 100μA, VIN = 5V
VIN = 5V, rising threshold at ON or INC
2.7V VIN 13.2V
Propagation Delay
tD,COMP
10mV overdrive, ON going positive or
negative, INC going negative
INC going positive
0.1 0.6 V
1 kΩ
1.164 1.2 1.236
V
1 8 mV
0.6 3 mV
0.575 0.6 0.625
V
3 mV
±1 mV/V
10 μs
100 150 200 ms
_______________________________________________________________________________________ 3

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3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +2.7V to +13.2V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = +5V and TA = +25°C.) (Note 3)
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
IB,COMP
0.001
1
μA
ON Pulse Width Low (Note 7)
tRESTART
To unlatch a fault MAX4271, MAX4273 with
CTIM = IN
20
μs
DIGITAL OUTPUTS (STAT, OUTC)
Output Leakage Current
Output Voltage Low
VOL
RETRY TIMING (MAX4272, MAX4273)
VSTAT 13.2, VOUTC 13.2
ISINK = 1mA
1 μA
0.4 V
Retry Timeout Period
tRETRY 100nF capacitor on CTIM (Note 5)
0.5 1 2 s
Default Retry
Timeout Period
tRETRY
(default)
CTIM = no connection
176 µs
UNDERVOLTAGE LOCKOUT (UVLO)
Threshold
VUVLO
Startup is initiated when this threshold is
exceeded at IN
2.25
2.67 V
Hysteresis
VUVLO,HYST
100 mV
Delay
tD,UVLO
Time the input voltage must exceed
undervoltage lockout before startup is
initiated
100 150 200 ms
Note 3: All devices are 100% tested at TA = +25°C. 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 CTON = 10nF (MAX4273) and CTIM = 1nF.
Note 6: The current available at GATE is a function of VGATE (see Typical Operating Characteristics).
Note 7: Guaranteed by design.
4 _______________________________________________________________________________________

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3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
Typical Operating Characteristics
(VIN = 5V, RSENSE = 100mΩ, CBOARD = 47µF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
1.0
0.9
0.8 ON = VIN
0.7 IGATE = 10μA
0.6
0.5
0.4
0.3 ON = GND
0.2
0.1
0
0 2 4 6 8 10 12 14
VIN (V)
SUPPLY CURRENT vs. TEMPERATURE
1.0
ON = VIN
0.9
0.8 VIN = 12V
0.7 VIN = 5V
0.6
0.5
0.4
0.3 VIN = 3V
0.2
0.1
0
-40 -15 10 35 60
TEMPERATURE (°C)
85
SLOW COMPARATOR
RESPONSE TIME vs. INPUT VOLTAGE
MAX4271/3-03
240 24
230 23
CSPD = 110nF
TIME IN ms
220 22
210 21
200 20
CSPD = 0
TIME IN μs
190 19
180 18
0 2 4 6 8 10 12 14
VIN (V)
SLOW COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
51.0
50.8 TA = +25°C
50.6 TA = -40°C
50.4
50.2
50.0
49.8
49.6 TA = +85°C
49.4
49.2
49.0
0 2 4 6 8 10 12 14
VIN (V)
FAST COMPARATOR THRESHOLD
vs. INPUT VOLTAGE
210
208
206
204 TA = -40°C
202 TA = +25°C
200
198
196 TA = +85°C
194
192
190
0 2 4 6 8 10 12 14
VIN (V)
FAST COMPARATOR RESPONSE TIME
vs. OVERDRIVE VOLTAGE
450
400 VIN = 12V
350
300
VIN = 3V
250
VIN = 5V
200
1
10 100
OVERDRIVE VOLTAGE (mV)
1000
TIME TO FAST DISCHARGE GATE
vs. CGATE
100k
NO EXTERNAL MOSFET
10k DISCHARGE TO VGATE = 0.1V
1k
VIN = 12V
100
VIN = 5V
10
1 VIN = 3V
0.1
0.01
0.1
1 10
CGATE (nF)
100 1000
FAST COMPARATOR RESPONSE TIME
vs. TEMPERATURE
500
450
400 VIN = 12V
350
300 VIN = 5V
250 VIN = 3V
200
-40
-15 10 35 60
TEMPERATURE (°C)
85
STARTUP PERIOD
vs. INPUT VOLTAGE
350 35MAX4271/3-09
CTIM = 100nF
330 TIME IN ms 33
310 31
290
CTIM = 1nF
TIME IN μs
29
270 27
250 25
0 2 4 6 8 10 12 14
VIN (V)
_______________________________________________________________________________________ 5