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MAX4944ELA+MAXIMN/a100avaiOvervoltage-Protection Controllers with Internal FET
MAX4944ELA+TMAXIMN/a510avaiOvervoltage-Protection Controllers with Internal FET
MAX4944LELA+MAXIMN/a270avaiOvervoltage-Protection Controllers with Internal FET
MAX4945AELA+MAXIMN/a2700avaiOvervoltage-Protection Controllers with Internal FET
MAX4945LELA+TMAXIMN/a19avaiOvervoltage-Protection Controllers with Internal FET
MAX4946ELA+MAXIMN/a500avaiOvervoltage-Protection Controllers with Internal FET


MAX4945AELA+ ,Overvoltage-Protection Controllers with Internal FETFeaturesThe MAX4943–MAX4946/MAX4949 family of overvolt- ♦ Input Voltage Protection Up to +28Vage-pr ..
MAX4945LELA+T ,Overvoltage-Protection Controllers with Internal FETFeaturesThe MAX4943–MAX4946/MAX4949 family of overvolt- ♦ Input Voltage Protection Up to +28Vage-pr ..
MAX4946ELA+ ,Overvoltage-Protection Controllers with Internal FETELECTRICAL CHARACTERISTICS(V = +5V (MAX4943/MAX4944_/MAX4945_/MAX4949), V = +3V (MAX4946), T = -40° ..
MAX4947ETG+ ,Hex SPDT Data SwitchApplications♦ Wide Supply Capability1.8V to 5.5V Supply Voltage RangeUSB Signal Switching Cell Phon ..
MAX494CSD ,Single/Dual/Quad, Micropower, Single-Supply Rail-to-Rail Op AmpsGeneral Description ________
MAX494CSD+ ,Single/Dual/Quad, Micropower, Single-Supply, Rail-to-Rail Op AmpsGeneral Description ________
MAX9117EXK-T ,SC70, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without ReferenceApplications2-Cell Battery Monitoring/ManagementOrdering InformationUltra-Low-Power SystemsTEMP PIN ..
MAX9118EXK+ ,SC70, 1.6V, Nanopower, Beyond-the-Rails Comparators With/Without Referencefeatures make the MAX9117–MAX9120 family of♦ Guaranteed to Operate Down to +1.6Vcomparators ideal f ..
MAX9118EXK+T ,SC70, 1.6V, Nanopower, Beyond-the-Rails Comparators With/Without ReferenceFeaturesThe MAX9117–MAX9120 nanopower comparators in ♦ Space-Saving SC70 Package (Half the Size ofs ..
MAX9118EXK-T ,SC70 / 1.8V / Nanopower / Beyond-the-Rails Comparators With/Without ReferenceFeaturesThe MAX9117–MAX9120 nanopower comparators in Space-Saving SC70 Package (Half the Size ofsp ..
MAX9119EXK+T ,SC70, 1.6V, Nanopower, Beyond-the-Rails Comparators With/Without ReferenceELECTRICAL CHARACTERISTICS—MAX9117/MAX9118 (with REF)(V = +5V, V = 0V, V = V , T = -40°C to +85°C, ..
MAX9119EXK-T ,SC70 / 1.8V / Nanopower / Beyond-the-Rails Comparators With/Without ReferenceELECTRICAL CHARACTERISTICS—MAX9117/MAX9118(V = +5V, V = 0V, V = V , T = -40°C to +85°C, unless othe ..


MAX4944ELA+-MAX4944ELA+T-MAX4944LELA+-MAX4945AELA+-MAX4945LELA+T-MAX4946ELA+
Overvoltage-Protection Controllers with Internal FET
General Description
The MAX4943–MAX4946/MAX4949 family of overvolt-
age-protection devices feature a low 80mΩ(typ) RON
internal FET and protect low-voltage systems against
voltage faults up to +28V. These devices also drive an
optional external pFET to protect down to -28V when
connected to a load with reverse current protection.
When the input voltage exceeds the overvoltage thresh-
old, the internal FET is turned off to prevent damage to
the protected components.
All switches feature a minimum 1.2A current-limit pro-
tection. During a short-circuit occurrence, the
MAX4944B and MAX4945B place the switch in a
latchoff state where the switch turns off and remains off.
For the autoretry devices, the switch turns off and con-
tinuously checks after a 15ms (typ) retry time.
The overvoltage thresholds (OVLO) are preset to 7.4V,
6.35V, 5.8V, 4.56V, or 8.9V. The undervoltage-lockout
(UVLO) thresholds are preset to 2.45V and 4.15V.
When the input voltage drops below the undervoltage-
lockout (UVLO) threshold, the devices enter a low-
current standby mode. (See the Ordering Information/
Selector Guidefor more details on UVLO/OVLO).
All devices are offered in a small, 8-pin µDFN (2mm x
2mm) package and are specified for operation over the
-40°C to +85°C temperature range.
Applications
Features
Input Voltage Protection Up to +28VIntegrated nFET Switch Preset Overvoltage Protection Trip Level
7.40V (MAX4943)
6.35V (MAX4944_)
5.80V (MAX4945_)
4.56V (MAX4946)
8.90V (MAX4949)
Low-Current Undervoltage-Lockout ModeShort-Circuit Protection (Latchoff/Autoretry) Internal 15ms (typ) Startup Delay and Retry TimesInput Voltage Power-Good Logic OutputThermal-Shutdown ProtectionSmall, 8-Pin (2mm x 2mm) µDFN Package
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Overvoltage-Protection Controllers with
Internal FET

19-0552; Rev 3; 6/08
Ordering Information/Selector Guide
PARTPIN-PACKAGETOP MARKPKG CODEUVLO (V)OVLO (V)OVERCURRENT MODE
MAX4943ELA+T*
8 µDFNABAL822-14.157.40Retry
MAX4944ELA+T
8 µDFNABBL822-14.156.35Retry
MAX4944BELA+T*8 µDFNABCL822-14.156.35Latchoff
MAX4944LELA+T
8 µDFNABDL822-12.456.35Retry
MAX4945ELA+T**
8 µDFNABEL822-14.155.80Retry
MAX4945AELA+T**
8 µDFNADWL822-14.155.80Retry
MAX4945BELA+T*8 µDFNABFL822-14.155.80Latchoff
MAX4945LELA+T
8 µDFNABGL822-12.455.80Retry
MAX4946ELA+T
8 µDFNABHL822-12.454.56Retry
MAX4949ELA+T
8 µDFNADTL822-12.458.90Latchoff
Note: All devices are specified over the -40°C to +85°C operating temperature range.

+Denotes a lead-free/RoHS-compliant package.
T= Tape-and-reel package.
*Future product—contact factory for availability.
TOP VIEW
OUT
GNDACOK
OUT
OUTINMAX4943–
MAX4946/
MAX4944L/
MAX4945A/
MAX4945L/
MAX4949
µDFN
2mm × 2mm
Pin Configuration

Cell Phones
Digital Still Cameras
PDAs and Palmtop Devices
MP3 Players
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Overvoltage-Protection Controllers with
Internal FET
ABSOLUTE MAXIMUM RATINGS

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.
IN............................................................................-0.3V to +30V
OUT...............................................................-0.3V to (IN + 0.3V)
GP...........................................................................-0.3V to +12V
IN to GP..................................................................-0.3V to +22V
ACOK.......................................................................-0.3V to +6V
Continuous Power Dissipation (TA= +70°C)
8-Pin µDFN (derate 4.8mW/°C above +70°C)..............381mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS

(VIN= +5V (MAX4943/MAX4944_/MAX4945_/MAX4949), VIN= +3V (MAX4946), TA= -40°C to +85°C, unless otherwise noted.
Typical values are at TA= +25°C.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS

Input Voltage RangeVIN2.228.0V
VIN = 3V (MAX4946)50150Input Supply CurrentIINVIN = 5V, all remaining parts50150µA
UVLO Supply CurrentIUVLOVIN = 2.2V30µA
MAX4943/MAX4944/
MAX4944B/MAX4945/
MAX4945A/ MAX4945B
IN Undervoltage LockoutVUVLO(VIN falling)
MAX4944L/MAX4945L/
MAX4946/MAX49492.302.452.60
IN Undervoltage-Lockout
Hysteresis1%
MAX49437.007.47.80
MAX4944_6.006.356.70
MAX4945/MAX4945B/L5.505.806.10
MAX4945A5.505.806.00
MAX49464.304.564.82
Overvoltage Trip LevelVOVLO(VIN rising)
MAX49498.208.909.60
IN Overvoltage Hysteresis1%
VIN = 3V (MAX4946), IOUT = 1A80200Switch On-ResistanceRONVIN = 5V, all remaining parts, IOUT = 1A80200mΩ
TA = +25°C1.21.74.0MAX4943–MAX4946TA = TMIN to TMAX1.21.74.0
TA = +25°C2.03.55.0Overcurrent Protection ThresholdILIM
MAX4949TA = TMIN to TMAX2.03.05.0
GP Clamp VoltageIGPD(VIN - VGP), VIN = 28V131619V
GP Pulldown ResistorRGPD50kΩ
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Overvoltage-Protection Controllers with
Internal FET
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS

ACOK Output-Low VoltageVOLISINK = 1mA0.4V
ACOK High-Leakage CurrentV ACOK = 5.5V1µA
Thermal Shutdown+175°C
Thermal-Shutdown Hysteresis40°C
Load Capacitor300µF
TIMING CHARACTERISTICS (Figure 2)

Debounce TimetINDBCTime from VUVLO < VIN < VOVLO to charge-
pump enable15ms
Switch Turn-On TimetON
VUVLO < VIN < VOVLO, RLOAD = 100Ω,
CLOAD = 300µF, VOUT = from 10% of VOUT
to 80% of VOUT
6ms
ACOK Assertion Timet ACOKVUVLO < VIN < VOVLO, to ACOK low30ms
VIN < VUVLO or VIN > VOVLO, to internal
switch off220µsSwitch Turn-Off TimetOFF
Overcurrent fault to internal switch turn-off10µs
Autoretry TimetRETRYFrom overcurrent fault to internal switch
turn-on15ms
ELECTRICAL CHARACTERISTICS (continued)

(VIN= +5V (MAX4943/MAX4944_/MAX4945_/MAX4949), VIN= +3V (MAX4946), TA= -40°C to +85°C, unless otherwise noted.
Typical values are at TA= +25°C.) (Note 1)
Note 1:
All specifications are 100% production tested at TA= +25°C, unless otherwise noted. Specifications are over -40°C to +85°C
and are guaranteed by design.
Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4943 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (nA)
MAX4944
RON
vs. TEMPERATURE
MAX4943 toc02
TEMPERATURE (°C)
(m
NORMALIZED UVLO THRESHOLD
vs. TEMPERATURE
MAX4943 toc03
TEMPERATURE (°C)
NORMALIZED UVLO THRESHOLD
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Overvoltage-Protection Controllers with
Internal FET
Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)
NORMALIZED OVLO THRESHOLD
vs. TEMPERATURE
MAX4943 toc04
TEMPERATURE (°C)
NORMALIZED OVLO THRESHOLD
ACOK ASSERTION TIME
vs. TEMPERATURE

MAX4943 toc05
TEMPERATURE (°C)
ACOK ASSERTION TIME (ms)3510-15
DEBOUNCE TIME
vs. TEMPERATURE
MAX4943 toc06
TEMPERATURE (°C)
DEBOUNCE TIME (ms)
10ms/div
POWER-UP RESPONSE

ADAPTER
5V/div
MAX4943 toc07
VIN
5V/div
VOUT
5V/div
VACOK
5V/div
IOUT
2A/div
4μs/div
UNDERVOLTAGE FAULT RESPONSE

ADAPTER
2V/div
MAX4943 toc08
VIN
2V/div
VOUT
5V/div
VACOK
5V/div
IOUT
1A/div
1μs/div
SHORT-CIRCUIT FAULT RESPONSE

ADAPTER
2V/div
MAX4943 toc09
VIN
5V/div
VOUT
5V/div
VACOK
5V/div
IOUT
10A/divCIN = 1000μF
10μs/div
OVERCURRENT DURATION TIME
(DURING AUTORETRY)

MAX4943 toc10
VOUT
1V/div
IOUT
1A/div
RLOAD = 1Ω
COUT = 0.1μF
Detailed Description
The MAX4943–MAX4946/MAX4949 overvoltage-protec-
tion devices feature a low RONinternal FET and protect
low-voltage systems against voltage faults up to +28V. If
the input voltage exceeds the overvoltage threshold, the
internal MOSFET is turned off to prevent damage to the
protected components. These devices also drive an
optional external pFET to protect down to -28V. If the
adapter voltage drops below ground, the pFET turns off
to prevent damage to the protected components due to
negative voltage exposure. The internal charge pump’s
15ms (typ) debounce time prevents false turn-on of the
internal switch during startup. An open-drain, active-low
logic output is available to signal that a successful
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Overvoltage-Protection Controllers with
Internal FET
Pin Description
PINNAMEFUNCTION

1, 2IN
Voltage Input. IN powers the charge pump required to turn on the internal switch. When the correct
adapter is plugged in, a 15ms (typ) debouncer prevents false turn-on of the internal switch. Bypass
IN to GND with a 1µF ceramic capacitor as close as possible to the device to enable ±15kV (HBM)
ESD protection on IN.GPpFET Gate-Drive Output. GP pulls the external pFET gate down when the input is above ground.ACOK
Active-Low Open-Drain Adapter-Voltage Indicator Output. ACOK is driven low after the adapter
voltage is stable between VUVLO and VOVLO for 30ms (typ). Connect a pullup resistor from ACOK to
the logic I/O voltage of the host system.GNDGround
6, 7, 8OUTOutput Voltage. Output of internal switch. Short all pins together for proper operation.
OUT
VOVLO
15ms (typ)
DEBOUNCE
TIMER AND
RETRY TIME
30ms (typ)
TIMER
OSCILLATOR
CHARGE
PUMP
OVERCURRENT
THERMAL
FAULTS
GND
CHARGE-PUMP
ENABLED
VUVLO
ACOK
MAX4943–MAX4946/MAX4944L/
MAX4945L/MAX4949
RESET
RESET
Figure 1. Functional Diagram
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Device Operation

The MAX4943–MAX4946/MAX4949 have an internal
oscillator and charge pump that control the turn-on
of the internal switch. The internal oscillator controls
the timers that enable the turn-on of the charge pump
and controls the state of the open-drain ACOK
output. If VIN< VUVLOor if VIN >VOVLO, the internal
oscillator remains off, thus disabling the charge pump.
If VUVLO< VIN < VOVLO, the internal charge pump is
enabled. The charge-pump startup, after a 15ms (typ)
internal delay, turns on the internal switch (see Figure 2).
ACOKis held high during startup until the ACOK30ms
(typ) blanking period expires. At this point, the device is
in its on state.
At any time, if VINdrops below VUVLOor rises above
VOVLO, ACOKis pulled high and the charge pump
is disabled.
Internal Switch

The MAX4943–MAX4946/MAX4949 incorporate an
internal nFET with a 80mΩ(typ) RON. The switch is
internally driven by a charge pump that generates a 5V
voltage above the input voltage. The internal switch is
equipped with 1.2A (min) current-limit protection that
turns off the switch within 10µs (typ) during an overcur-
rent fault condition.
Autoretry

The MAX4943–MAX4946 have an overcurrent autoretry
function that turns on the switch again after a 15ms (typ)
retry time (see Figure 3). If the faulty load condition is still
present after the blanking time, the switch turns off again
and the cycle is repeated. The fast turn-off time and
15ms retry time result in a very low duty cycle to keep
power consumption low. If the faulty load condition is not
present, the switch remains on.
Latch

The MAX4944B/MAX4945B/MAX4949 do not have the
autoretry function, and the switch latches off after an
overcurrent fault. The switch remains off until the over-
current fault has been removed. The switch turns back
on when the adapter voltage goes below VUVLOand
then returns to the valid operating range.
Overvoltage-Protection Controllers with
Internal FET

OVLO
UVLO
tINDBC
tON
OUT
ACOK
tINDBC
tOFF
tINDBC
80% VIN
tACOK
tOFF
tACOK
10% VIN
Figure 2. Timing Diagram
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