19-0552; Rev 3; 6/08
Overvoltage-Protection Controllers with
Internal FET
General Description
The MAX4943–MAX4946/MAX4949 family of overvolt-
age-protection devices feature a low 80mΩ (typ) R
ON
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 Guide
for 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.
♦
Input Voltage Protection Up to +28V
♦
Integrated 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 Mode
♦
Short-Circuit Protection (Latchoff/Autoretry)
♦
Internal 15ms (typ) Startup Delay and Retry Times
♦
Input Voltage Power-Good Logic Output
♦
Thermal-Shutdown Protection
♦
Small, 8-Pin (2mm x 2mm) µDFN Package
Features
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Pin Configuration
TOP VIEW
+
IN 1
IN 2
GP 3
ACOK 4
MAX4943–
MAX4946/
MAX4944L/
MAX4945A/
MAX4945L/
MAX4949
8 OUT
7 OUT
6 OUT
5 GND
Applications
Cell Phones
Digital Still Cameras
PDAs and Palmtop Devices
MP3 Players
µDFN
2mm
×
2mm
Ordering Information/Selector Guide
PART
MAX4943ELA+T*
MAX4944ELA+T
MAX4944BELA+T*
MAX4944LELA+T
MAX4945ELA+T**
MAX4945AELA+T**
MAX4945BELA+T*
MAX4945LELA+T
MAX4946ELA+T
MAX4949ELA+T
PIN-PACKAGE
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
8 µDFN
TOP MARK
ABA
ABB
ABC
ABD
ABE
ADW
ABF
ABG
ABH
ADT
PKG CODE
L822-1
L822-1
L822-1
L822-1
L822-1
L822-1
L822-1
L822-1
L822-1
L822-1
UVLO (V)
4.15
4.15
4.15
2.45
4.15
4.15
4.15
2.45
2.45
2.45
OVLO (V)
7.40
6.35
6.35
6.35
5.80
5.80
5.80
5.80
4.56
8.90
OVERCURRENT MODE
Retry
Retry
Latchoff
Retry
Retry
Retry
Latchoff
Retry
Retry
Latchoff
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.
**The
OVLO is 6.10V (max) for the MAX4945ELA+T and .6.0V (max) for the MAX4945AELA+T.
________________________________________________________________
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.
Overvoltage-Protection Controllers with
Internal FET
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
ABSOLUTE MAXIMUM RATINGS
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 (T
A
= +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
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
(V
IN
= +5V (MAX4943/MAX4944_/MAX4945_/MAX4949), V
IN
= +3V (MAX4946), T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Input Voltage Range
Input Supply Current
UVLO Supply Current
SYMBOL
V
IN
I
IN
I
UVLO
V
IN
= 3V (MAX4946)
V
IN
= 5V, all remaining parts
V
IN
= 2.2V
MAX4943/MAX4944/
MAX4944B/MAX4945/
MAX4945A/ MAX4945B
MAX4944L/MAX4945L/
MAX4946/MAX4949
IN Undervoltage-Lockout
Hysteresis
MAX4943
MAX4944_
Overvoltage Trip Level
V
OVLO
(V
IN
rising)
MAX4945/MAX4945B/L
MAX4945A
MAX4946
MAX4949
IN Overvoltage Hysteresis
Switch On-Resistance
R
ON
V
IN
= 3V (MAX4946), I
OUT
= 1A
V
IN
= 5V, all remaining parts, I
OUT
= 1A
MAX4943–MAX4946
Overcurrent Protection Threshold
I
LIM
MAX4949
GP Clamp Voltage
GP Pulldown Resistor
I
GPD
R
GPD
(V
IN
- V
GP
), V
IN
= 28V
T
A
= +25°C
T
A
= T
MIN
to T
MAX
T
A
= +25°C
T
A
= T
MIN
to T
MAX
1.2
1.2
2.0
2.0
13
7.00
6.00
5.50
5.50
4.30
8.20
3.90
4.15
CONDITIONS
MIN
2.2
50
50
TYP
MAX
28.0
150
150
30
4.40
V
2.30
2.45
1
7.4
6.35
5.80
5.80
4.56
8.90
1
80
80
1.7
1.7
3.5
3.0
16
50
200
200
4.0
4.0
5.0
5.0
19
V
k
Ω
A
7.80
6.70
6.10
6.00
4.82
9.60
%
m
Ω
V
2.60
%
UNITS
V
µA
µA
IN Undervoltage Lockout
V
UVLO
(V
IN
falling)
2
_______________________________________________________________________________________
Overvoltage-Protection Controllers with
Internal FET
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +5V (MAX4943/MAX4944_/MAX4945_/MAX4949), V
IN
= +3V (MAX4946), T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
ACOK
Output-Low Voltage
ACOK
High-Leakage Current
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
SYMBOL
V
OL
I
SINK
= 1mA
V
ACOK
= 5.5V
CONDITIONS
MIN
TYP
MAX
0.4
1
UNITS
V
µA
°C
°C
Thermal Shutdown
Thermal-Shutdown Hysteresis
Load Capacitor
TIMING CHARACTERISTICS (Figure 2)
Debounce Time
t
INDBC
Time from V
UVLO
< V
IN
< V
OVLO
to charge-
pump enable
V
UVLO
< V
IN
< V
OVLO
, R
LOAD
= 100
Ω
,
C
LOAD
= 300µF, V
OUT
= from 10% of V
OUT
to 80% of V
OUT
V
UVLO
< V
IN
< V
OVLO
, to
ACOK
low
V
IN
< V
UVLO
or VIN > V
OVLO
, to internal
switch off
Overcurrent fault to internal switch turn-off
Autoretry Time
t
RETRY
From overcurrent fault to internal switch
turn-on
+175
40
300
µF
15
ms
Switch Turn-On Time
ACOK
Assertion Time
t
ON
t
ACOK
t
OFF
6
30
2
10
15
20
ms
ms
µs
µs
ms
Switch Turn-Off Time
Note 1:
All specifications are 100% production tested at T
A
= +25°C, unless otherwise noted. Specifications are over -40°C to +85°C
and are guaranteed by design.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4943 toc01
R
ON
vs. TEMPERATURE
MAX4943 toc02
NORMALIZED UVLO THRESHOLD
vs. TEMPERATURE
1.008
NORMALIZED UVLO THRESHOLD
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
0.990
MAX4943 toc03
300
270
240
SUPPLY CURRENT (nA)
210
MAX4944
140
120
100
R
ON
(mΩ)
80
60
40
20
0
1.010
180
150
120
90
60
30
0
2
6
10
14
18
22
26
SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
Overvoltage-Protection Controllers with
Internal FET
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
NORMALIZED OVLO THRESHOLD
vs. TEMPERATURE
1.008
NORMALIZED OVLO THRESHOLD
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992
0.990
-40
-15
10
35
60
85
TEMPERATURE (°C)
30
-40
-15
10
35
60
85
TEMPERATURE (°C)
15
-40
-15
10
35
60
85
TEMPERATURE (°C)
MAX4943 toc04
ACOK ASSERTION TIME
vs. TEMPERATURE
MAX4943 toc05
DEBOUNCE TIME
vs. TEMPERATURE
MAX4943 toc06
MAX4943 toc08
1.010
40
25
23
DEBOUNCE TIME (ms)
ACOK ASSERTION TIME (ms)
38
36
21
34
19
32
17
POWER-UP RESPONSE
MAX4943 toc07
UNDERVOLTAGE FAULT RESPONSE
5V
ADAPTER
5V/div
V
IN
5V/div
V
OUT
5V/div
V
ACOK
5V/div
I
OUT
2A/div
0
4μs/div
3V ADAPTER
2V/div
5V
V
IN
3V
2V/div
V
OUT
0
5V/div
V
ACOK
5V/div
I
OUT
0 1A/div
10ms/div
SHORT-CIRCUIT FAULT RESPONSE
MAX4943 toc09
OVERCURRENT DURATION TIME
(DURING AUTORETRY)
MAX4943 toc10
ADAPTER
2V/div
V
IN
5V/div
V
OUT
5V/div
V
ACOK
5V/div
I
OUT
10A/div
R
LOAD
= 1Ω
C
OUT
= 0.1μF
V
OUT
1V/div
I
OUT
1A/div
C
IN
= 1000μF
1μs/div
10μs/div
4
_______________________________________________________________________________________
Overvoltage-Protection Controllers with
Internal FET
Pin Description
PIN
NAME
FUNCTION
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.
pFET Gate-Drive Output. GP pulls the external pFET gate down when the input is above ground.
Active-Low Open-Drain Adapter-Voltage Indicator Output.
ACOK
is driven low after the adapter
voltage is stable between V
UVLO
and V
OVLO
for 30ms (typ). Connect a pullup resistor from
ACOK
to
the logic I/O voltage of the host system.
Ground
Output Voltage. Output of internal switch. Short all pins together for proper operation.
MAX4943–MAX4946/MAX4944L/MAX4945A/MAX4945L/MAX4949
1, 2
IN
3
4
5
6, 7, 8
GP
ACOK
GND
OUT
IN
OUT
CHARGE
PUMP
GP
CHARGE-PUMP
ENABLED
15ms (typ)
DEBOUNCE
TIMER AND
RETRY TIME
OVERCURRENT
OR
THERMAL
FAULTS
GND
V
OVLO
RESET
+
-
OSCILLATOR
V
UVLO
+
-
RESET
30ms (typ)
TIMER
ACOK
MAX4943–MAX4946/MAX4944L/
MAX4945L/MAX4949
Figure 1. Functional Diagram
Detailed Description
The MAX4943–MAX4946/MAX4949 overvoltage-protec-
tion devices feature a low R
ON
internal 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
power-up has occurred.
5
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