19-3649; Rev 5; 12/09
Overvoltage Protection Controllers with
Low Standby Current
General Description
The MAX4843–MAX4846 overvoltage protection con-
trollers protect low-voltage systems against high-voltage
faults of up to 28V. When the input voltage exceeds the
overvoltage threshold, these devices turn off a low-cost,
external n-channel FET(s) to prevent damage to the pro-
tected components. An internal charge pump eliminates
the need for external capacitors and drives the FET gate
for a simple, robust solution.
The overvoltage trip level is set to 7.4V (MAX4843),
6.35V (MAX4844), 5.8V (MAX4845), or 4.65V
(MAX4846). When the input voltage drops below the
undervoltage lockout (UVLO) threshold, the devices
enter a low standby current mode (10µA). The
MAX4843/MAX4844/MAX4845 have a UVLO threshold
of 4.15V, the MAX4845C/MAX4845D have a UVLO
threshold of 2.2V, and the MAX4846 has a UVLO
threshold of 2.5V. In addition to the single FET configu-
ration, the devices can be configured with back-to-
back external FETs to prevent currents from being
back-driven into the adapter.
An additional feature includes a ±15kV ESD-protected
input when bypassed with a 1µF capacitor to ground.
All devices are offered in small 6-pin µDFN (1.5mm x
1.0mm) and 6-pin ultra-thin LGA (MAX4845 and
MAX4846 only) (1.5mm x 1.0mm) packages and are
specified for operation over the -40°C to +85°C temper-
ature range.
♦
Overvoltage Protection Up to 28V
♦
Preset 7.4V, 6.35V, 5.8V, or 4.65V Overvoltage Trip
Level
♦
Low (10µA) Undervoltage Lockout Standby
Current
♦
Drives Low-Cost nMOSFET
♦
Internal 50ms Startup Delay
♦
Internal Charge Pump
♦
Overvoltage Fault FLAG Indicator
♦
6-Pin (1.5mm x 1.0mm) µDFN Package
Features
MAX4843–MAX4846
Ordering Information
PART
MAX4843ELT
MAX4844ELT
MAX4845ELT
MAX4845EYT+T
MAX4845CEYT+T
MAX4845DEYT+T
MAX4846ELT
MAX4846EYT+T
PIN-
PACKAGE
6 μDFN
6 μDFN
6 μDFN
6 UTLGA
6 UTLGA
6 UTLGA
6 μDFN
6 UTLGA
UVLO
(V)
4.15
4.15
4.15
4.15
2.20
2.20
2.50
2.50
OVLO
(V)
7.40
6.35
5.80
5.80†
5.80†
5.80
4.65
4.65
TOP
MARK
BE
BF
BG
AC
AP
AQ
BH
AD
Applications
Cell Phones
Digital Still Cameras
PDAs and Palmtop Devices
MP3 Players
Note:
All devices are specified over the -40°C to +85°C tem-
perature range.
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
†OVLO maximum is 6.0V for the MAX4845C and 5.9V for the
MAX4845D.
Typical Operating Circuit
INPUT
+1.2V TO +28V
Pin Configurations
TOP VIEW
N.C.
6
N.C.
5
GATE
4
N.C.
6
N.C.
5
GATE
4
N
OUTPUT
1
1μF
IN
GATE
4
V
IO
MAX4843–
MAX4846
1
2
GND
3
FLAG
1
IN
MAX4845
MAX4846
2
GND
3
FLAG
MAX4843–
MAX4846
2
GND
FLAG
3
IN
μDFN
ULTRA-THIN LGA
________________________________________________________________
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
Low Standby Current
MAX4843–MAX4846
ABSOLUTE MAXIMUM RATINGS
IN to GND ..............................................................-0.3V to +30V
GATE to GND ........................................................-0.3V to +12V
FLAG to GND ..........................................................-0.3V to +6V
Continuous Power Dissipation (T
A
= +70°C)
6-Pin µDFN (derate 2.1mW/°C above +70°C) .........167.7mW
6-Pin Ultra-Thin LGA (derate 2.1mW/°C
above +70°C) ...........................................................170.2mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature .................................................... +150°C
Storage Temperature Range ............................-65°C to +150°C
Soldering Temperature (reflow)
6-Pin µDFN...................................................................+240°C
6-Pin Ultra-Thin LGA ....................................................+260°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 for MAX4843/MAX4844/MAX4845, V
IN
= +4V for MAX4846, C
GATE
= 500pF, T
A
= -40°C to +85°C, unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Input Voltage Range
Undervoltage Lockout Threshold
Undervoltage Lockout
Hysteresis
SYMBOL
V
IN
MAX4843/MAX4844/MAX4845
UVLO
V
IN
falling
MAX4845C/MAX4845D
MAX4846
MAX4843/MAX4844/MAX4845
MAX4846
MAX4843
MAX4844
Overvoltage Trip Level
OVLO
V
IN
rising
MAX4845
MAX4845C
MAX4845D
MAX4846
MAX4843
Overvoltage Lockout Hysteresis
MAX4844
MAX4845
MAX4846
IN Supply Current
UVLO Supply Current
Gate Voltage
GATE Pulldown Current
FLAG Output Low Voltage
FLAG Leakage Current
I
IN
I
UVLO
V
GATE
I
PD
V
OL
MAX4843/MAX4844/MAX4845
MAX4846
V
IN
= 3.8V MAX4843/MAX4844/MAX4845
V
IN
= 2.2V
1μA load
MAX4846
MAX4843/MAX4844/MAX4845
MAX4846
9
7.5
10
7.0
6.0
5.5
5.5
5.5
4.35
CONDITIONS
MIN
1.2
3.9
1.8
2.3
4.15
2.2
2.5
41
25
7.4
6.35
5.8
5.8
5.8
4.65
75
65
55
50
70
60
10
8
9.83
7.85
27
0.4
1
120
110
22
18
10
8.0
μA
μA
V
mA
V
μA
mV
7.8
6.7
6.1
6.0
5.9
4.95
V
TYP
MAX
28.0
4.4
2.5
2.7
mV
V
UNITS
V
V
IN
> OVLO, V
GATE
= 5.5V
I
SINK
= 1mA, FLAG deasserted
V
FLAG
= 5.5V, FLAG asserted
2
_______________________________________________________________________________________
Overvoltage Protection Controllers with
Low Standby Current
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +5V for MAX4843/MAX4844/MAX4845, V
IN
= +4V for MAX4846, C
GATE
= 500pF, T
A
= -40°C to +85°C, unless otherwise
noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
TIMING
Startup Delay
t
START
t
BLANK
V
IN
= UVLO rising to V
GATE
= 0.3V rising
(Figure 1)
V
GATE
= 0.3V rising to V
FLAG
= 0.3V falling
(Figure 1)
V
GATE
= 0.3V to 8V
(MAX4843/MAX4844/MAX4845),
V
GATE
= 0.3V to 7V (MAX4846) (Figure 1)
V
IN
rising at 1V/μs from 5V to 8V
(MAX4843/MAX4844/MAX4845)
or from 4V to 7V (MAX4846)
to V
GATE
= 0.3V (Figure 2)
V
IN
rising at 1V/μs from 5V to 8V
(MAX4843/MAX4844/MAX4845)
or from 4V to 7V (MAX4846), to V
FLAG
=
2.4V, R
FLAG
= 10k to 3V (Figure 2)
V
IN
rising at 1V/μs from 0V to 9V, time from
V
IN
= 5V to I
GATE
= 80% of I
PD
(Figure 3)
20
50
80
ms
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX4843–MAX4846
FLAG Blanking Time
20
50
80
ms
Gate Turn-On Time
t
GON
10
ms
Gate Turn-Off Time
t
GOFF
6
20
μs
FLAG Assertion Delay
t
FLAG
5.8
μs
Initial Overvoltage Fault Delay
t
OVP
1.5
μs
Note 1:
All devices are 100% tested at +25°C. Electrical limits across the full temperature range are guaranteed by design and correlation.
Typical Operating Characteristics
(V
IN
= +5V for MAX4843/MAX4844/MAX4845, V
IN
= +4V for MAX4846, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(MAX4843)
MAX4843-46 toc01
REVERSE CURRENT vs. OUTPUT VOLTAGE
(MAX4843)
100
REVERSE CURRENT (μA)
10
1
0.1
0.01
0.001
BACK-TO-BACK FET
SINGLE FET
MAX4843-46 toc02
GATE VOLTAGE vs. INPUT VOLTAGE
(MAX4843/MAX4844/MAX4845)
MAX4843-46 toc03
100
1000
15
MAX4844
MAX4843
80
SUPPLY CURRENT (μA)
12
GATE VOLTAGE (V)
MAX4845
9
60
40
6
20
0.0001
0.00001
3
0
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
0.000001
1
2
4
3
5
6
OUTPUT VOLTAGE (V)
7
0
3
4
5
6
7
8
INPUT VOLTAGE (V)
_______________________________________________________________________________________
3
Overvoltage Protection Controllers with
Low Standby Current
MAX4843–MAX4846
Typical Operating Characteristics (continued)
(V
IN
= +5V for MAX4843/MAX4844/MAX4845, V
IN
= +4V for MAX4846, T
A
= +25°C, unless otherwise noted.)
GATE VOLTAGE vs. INPUT VOLTAGE
(MAX4846)
MAX4843-46 toc04
GATE VOLTAGE vs. INPUT VOLTAGE
(MAX4843)
MAX4843-46 toc05
POWER-UP RESPONSE
MAX4843-46 toc06
10
10.50
8
GATE VOLTAGE (V)
10.25
GATE VOLTAGE (V)
GATE CURRENT = 0
V
IN
0
V
GATE
0
5V/DIV
6
10.00
5V/DIV
4
9.75
2
GATE
CURRENT = 1μA
V
FLAG
0
5V/DIV
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
9.50
3
4
5
6
7
8
20ms/DIV
INPUT VOLTAGE (V)
POWER-UP RESPONSE
MAX4843-46 toc07
OVERVOLTAGE RESPONSE
MAX4843-46 toc08
POWER-UP OVERVOLTAGE RESPONSE
MAX4843-46 toc09
8V
V
IN
0
V
OUT
0
I
IN
0
V
FLAG
0
20ms/DIV
4μs/DIV
5V/DIV
V
FLAG
0
20μs/DIV
1A/DIV
I
GATE
0
5V/DIV
5V/DIV
V
GATE
0
10mA/DIV
V
FLAG
0
5V/DIV
V
IN
0
10V/DIV
V
GATE
0
5V/DIV
5V/DIV
V
IN
0
2V/DIV
8V
5V/DIV
Pin Description
PIN
μDFN
1
2
3
ULTRA-
THIN LGA
1
2
3
NAME
FUNCTION
IN
GND
FLAG
Voltage Input. IN is both the power-supply input and the overvoltage sense input. Bypass IN
to GND with a 1μF capacitor or larger.
Ground
Fault Indication Output. FLAG is asserted high during undervoltage lockout and overvoltage
lockout conditions. FLAG is deasserted during normal operation. FLAG is an open-drain
output.
Gate-Drive Output. GATE is the output of an on-chip charge pump. When V
UVLO
< V
IN
< V
OVLO
,
GATE is driven high to turn on the external n-channel MOSFET(s).
No Connection. Not internally connected. Do not connect.
4
5, 6
4
5, 6
GATE
N.C.
4
_______________________________________________________________________________________
Overvoltage Protection Controllers with
Low Standby Current
Functional Diagram
MAX4843–MAX4846
IN
5.5V
REGULATOR
2x CHARGE
PUMP
GATE DRIVER
GATE
GND
UVLO AND
OVLO
DETECTOR
CONTROL
LOGIC AND
TIMER
MAX4843–
MAX4846
FLAG
5V
V
IN
V
UVLO
t
GON
8V
t
START
V
GATE
0.3V
V
GATE
0.3V
V
IN
5V
t
GOFF
V
OVLO
t
FLAG
V
FLAG
t
BLANK
0.3V
V
FLAG
2.4V
Figure 1. Startup Timing Diagram
Figure 2. Shutdown Timing Diagram
V
IN
0V
V
OVLO
t
OVP
80%
I
GATE
Figure 3. Power-Up Overvoltage Timing Diagram
_______________________________________________________________________________________
5
京公网安备 11010802033920号
EEWORLD
