19-3649; Rev 0; 4/05
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, and the MAX4846 has a UVLO threshold of
2.5V. In addition to the single FET configuration, 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 a small (1.5mm x 1.0mm) 6-pin
µDFN package and are specified for operation over the
-40°C to +85°C temperature range.
Features
o
Overvoltage Protection Up to 28V
o
Preset 7.4V, 6.35V, 5.8V, or 4.65V Overvoltage Trip
Level
o
Low (10µA) Undervoltage Lockout Standby
Current
o
Drives Low-Cost n MOSFET
o
o
o
o
Internal 50ms Startup Delay
Internal Charge Pump
Overvoltage Fault FLAG Indicator
6-Pin (1.5mm x 1.0mm) µDFN Package
MAX4843–MAX4846
Ordering Information
PART*
MAX4843ELT
MAX4844ELT
MAX4845ELT
MAX4846ELT
PIN-
PACKAGE
6 µDFN
6 µDFN
6 µDFN
6 µDFN
UVLO
(V)
4.15
4.15
4.15
2.50
OVLO
(V)
7.40
6.35
5.80
4.65
TOP
MARK
BE
BF
BG
BH
*All
devices are specified over the -40°C to +85°C temperature
range.
Applications
Cell Phones
Digital Still Cameras
PDAs and Palmtop Devices
MP3 Players
Typical Operating Circuit
Pin Configuration
INPUT
+1.2V TO +28V
TOP VIEW
N
OUTPUT
IN 1
1
IN
GATE
4
GND 2
V
IO
6
N.C.
1µF
MAX4843–
MAX4846
5
N.C.
MAX4843–
MAX4846
2
GND
FLAG
3
FLAG 3
4
GATE
µDFN
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas 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
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 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
UVLO
V
IN
falling
MAX4843/MAX4844/MAX4845
MAX4846
CONDITIONS
MIN
1.2
3.9
2.3
4.15
2.5
41
25
MAX4843
Overvoltage Trip Level
OVLO
V
IN
rising
MAX4844
MAX4845
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
V
IN
= 2.2V
1µA load
MAX4843/MAX4844/MAX4845
MAX4846
MAX4843/MAX4844/MAX4845
MAX4846
9
7.5
10
7.0
6.0
5.5
4.35
7.4
6.35
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
4.95
V
TYP
MAX
28.0
4.4
2.7
UNITS
V
V
mV
MAX4843/MAX4844/MAX4845
MAX4846
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
= 10kΩ 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
5V/DIV
6
10.00
0
9.75
GATE
CURRENT = 1µA
V
FLAG
0
5V/DIV
4
2
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
5V/DIV
V
IN
0
10V/DIV
V
GATE
10mA/DIV
V
FLAG
0
0
5V/DIV
5V/DIV
V
IN
0
2V/DIV
8V
5V/DIV
Pin Description
PIN
1
2
3
4
5, 6
NAME
IN
GND
FLAG
GATE
N.C.
FUNCTION
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.
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
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