General Description
The MAX4373/MAX4374/MAX4375 low-cost, micropow-
er, high-side current-sense supervisors contain a high-
side current-sense amplifier, bandgap reference, and
comparator with latching output. They feature a voltage
output that eliminates the need for gain-setting resistors,
making them ideal for today’s notebook computers, cell
phones, and other systems where battery/DC current
monitoring is critical. High-side current monitoring is
especially useful in battery-powered systems since it
does not interfere with the ground path of the battery
charger. The 0 to +28V input common-mode range is
independent of the supply voltage, which ensures that
the current-sense feedback remains viable even when
connected to a battery pack in deep discharge.
The comparator output of the MAX4373/MAX4374/
MAX4375 is latched to provide a turn-off flag that
doesn’t oscillate. In addition, the MAX4374/MAX4375
contain a second comparator for use in window-detec-
tion functions. The MAX4373/MAX4374/MAX4375 are
available in three different gain versions (T = +20V/V,
F = +50V/V, H = +100V/V) and use an external sense
resistor to set the sensitivity of the input voltage to the
load current. These features offer a high level of inte-
gration, resulting in a simple and compact current-
sense solution.
The MAX4373/MAX4374/MAX4375 operate from a sin-
gle +2.7V to +28V supply and consume 50µA. They are
specified for the extended operating temperature range
(-40°C to +85°C) and are available in 8-pin and 10-pin
µMAX® packages.
Applications
Notebook Computers
Portable/Battery-Powered Systems
Smart Battery Packs/Chargers
Cell Phones
Power-Management Systems
General-System/Board-Level Current Monitoring
Precision Current Sources
Features
♦Current-Sense Amplifier plus Internal Comparator
and Bandgap Reference with Improved Accuracy
♦50µA Supply Current
♦Single +2.7V to +28V Operating Supply
♦1mV (max) Input Offset Voltage
♦2% (max) Full-Scale Accuracy
♦Internal Bandgap Reference (±1.6% Accuracy)
♦Latching Comparator Output
♦Three Gain Versions Available (+20V/V, +50V/V,
+100V/V)
♦High Accuracy +2V to +28V Common-Mode
Range, Functional Down to 0V, Independent of
Supply Voltage
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
________________________________________________________________
Maxim Integrated Products
1
MAX4373
RS-RS+
OUT
CIN
LOAD/
BATTERY
VCC = 2.7V TO 28V
VIN = 0 TO 28V
GND
VCC
RSENSE
+ VSENSE -ILOAD
VPULL-UP
(UP TO 5V)
R3
COUT
C1
0.1µF
R2
R1
RESET
Typical Operating Circuit
19-1630; Rev 4; 1/11
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.
Pin Configurations appear at end of data sheet.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Ordering Information
PART TEMP RANGE PIN-
PACKAGE
GAIN
(V/V)
MAX4373TEUA+ -40°C to +85°C 8 µMAX +20
MAX4373TESA+ -40°C to +85°C 8 SO +20
MAX4373FEUA+ -40°C to +85°C 8 µMAX +50
MAX4373FESA+ -40°C to +85°C 8 SO +50
MAX4373HEUA+ -40°C to +85°C 8 µMAX +100
MAX4373HESA+ -40°C to +85°C 8 SO +100
µMAX is a registered trademark of Maxim Integrated Products, Inc.
EVALUATION KIT
AVAILABLE
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, VRESET = 0V, RLOAD= 1MΩ, TA= TMIN to TMAX, unless otherwise noted.
Typical values are at TA= +25°C.) (Note 1)
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.
VCC, RS+, RS- to GND ...........................................-0.3V to +30V
OUT to GND ................................................-0.3V to the lesser of
(VCC + 0.3V) or +15V
CIN1, CIN2, RESET to GND ........................-0.3V to the lesser of
(VCC + 0.3V) or +12V
Differential Input Voltage (VRS+ - VRS-)..............................±0.3V
COUT1, COUT2 to GND........................................-0.3V to +6.0V
Current into Any Pin..........................................................±10mA
Continuous Power Dissipation (TA= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
14-Pin SO (derate 8.3mW/°C above +70°C)................667mW
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
Soldering Temperature (reflow) .......................................+260°C
mV
PARAMETER SYMBOL MIN TYP MAX UNITS
-25 2.0
Input Bias Current
IRS+
0 2.5
µA
Leakage Current IRS+, IRS- ±0.015 ±0.5 µA
Supply Current ICC 50 100 µA
IRS-
04
-50 4
Full-Scale Sense Voltage
(Note 4) VSENSE
150 170 mV
100 120
Common-Mode Input Range
(Note 3)
Operating Voltage Range
(Note 2) VCC 2.7 28 V
VCMR 028V
Common-Mode Rejection CMR 85 dB
OUT Voltage High VCC -
VOH 0.25 V
CONDITIONS
VRS+ ≤2V
VRS+ > 2V
VCC = 0V, VRS+ = 28V
VRS+ > 2V, VSENSE = 5mV
VRS+ > 2V
VRS+ ≤2V
VCC = 2.7V, IOUT = -500µA, VRS+ = 12V
Gain = +20V/V, +50V/V, VRS+ = 12V
Gain = +100V/V, VRS+ = 12V
VRS+ > 2V
Input Offset Voltage VOS
0.1 1
VCC = VRS+ = 12V
(Note 11)
TA= +25°C
TA= TMIN to TMAX 2
8.5 65IOUT = 100µA
IOUT = 10µA
OUT Voltage Low VOUT
2.5 mV
VCC = 2.7V,
VRS+ = 12V
±0.30 ±2TA= +25°C
VSENSE =
100mV
(Note 6)
±3
VCC = 12V,
VRS+ = 12V TA= TMIN to TMAX
±0.35 ±2
VCC = 28V,
VRS+ = 28V
TA= +25°C
±3TA= TMIN to TMAX
±5.0VCC = 12V, VRS+ = 0.1V
VSENSE = 6.25mV, VCC = 12V,
VRS+ = 12V (Note 7)
Total OUT Voltage Error
(Note 5) VOUT
±5.0
%
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, VRESET = 0V, RLOAD= 1MΩ, TA= TMIN to TMAX, unless otherwise noted.
Typical values are at TA= +25°C.) (Note 1)
±0.3 ±1.7
±2.7TA= -40°C to +85°C
TA= +25°C
VSENSE =
20mV to 100mV,
VCC = 12V, VRS+ =
12V, Gain = 100
Output Low Voltage VOL 0.6 VISINK = 1mA
Propagation Delay 4µs
CL= 10pF, RL= 10kΩpull-up to 5V,
5mV of overdrive
Input Bias Current IB±2.2 ±15 nA
Comparator Hysteresis -9 mV
0.1 ms
Saturation Recovery Time
(Note 8) VCC = 12V, VRS+ = 12V, CLOAD = 10pF
dB
ms
Power-Supply Rejection
Power-Up Time to 1% of Final
Value
PSR
20
VSENSE = 100mV to
6.25mV
VSENSE = 6.25mV to
100mV
±2.7TA= -40°C to +85°C
TA= +25°C
+50
+100
MAX437_F
MAX437_H
VSENSE = 6.25mV
VSENSE = 100mV,
Gain = +100V/V
VSENSE = 100mV,
Gain = +50V/V
VSENSE = 100mV,
Gain = +20V/V
50
110
120
PARAMETER SYMBOL MIN TYP MAX UNITS
72 87
OUT Output Resistance ROUT 1.5 Ω
Capacitive Load Stability 1000 pF
OUT Settling Time to 1% of
Final Value
20
µs
0.5
Comparator Threshold VTH
590 600 610 mV
Gain
-3dB Bandwidth BW
200
kHz
AV
+20
V/V
Gain Accuracy ∆AV
±0.3 ±1.7
%
CONDITIONS
VOUT = 2V, VRS+ > 2V
VSENSE = 100mV
No sustained oscillations
Gain = +20V/V,
VCC = 12V,
VRS+ = 12V,
CLOAD = 10pF
VSENSE = 100mV, CLOAD = 10pF,
VCC = 12V, VRS+ = 12V
TA= +25°C
VRS+ = 12V,
VCC = 12V,
CLOAD = 10pF
MAX437_T
VSENSE =
20mV to 150mV;
VCC = 12V; VRS+ =
12V; Gain = 20, 50
586 614TA= TMIN to TMAX
COMPARATOR (Note 9)
0
20
10
40
30
50
60
010155 202530
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4373 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
MAX4373
MAX4374/MAX4375
VSENSE = 5mV
44
45
46
47
48
49
50
51
52
0105 15202530
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
MAX4373 toc02
COMMON-MODE VOLTAGE (V)
SUPPLY CURRENT (µA)
MAX4374/MAX4375
MAX4373
VSENSE = 5mV
-2.0
-0.5
-1.0
-1.5
0
0.5
1.5
1.0
2.0
2684 10121416182022242628
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
MAX4373 toc03
SUPPLY VOLTAGE (V)
OUTPUT ERROR (%)
AV = +100V/V
AV = +20V/V
AV = +50V/V
VSENSE = 100mV
Typical Operating Characteristics
(VRS+ = +12V, VCC = +12V, RLOAD = 1MΩ, VRESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA= +25°C, unless
otherwise noted.)
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
4 _______________________________________________________________________________________
Note 1: All devices are 100% production tested at TA= +25°C. All temperature limits are guaranteed by design.
Note 2: Guaranteed by PSR test.
Note 3: Guaranteed by OUT Voltage Error test.
Note 4: Guaranteed by Gain Accuracy test. Output voltage is internally clamped not to exceed 12V.
Note 5: Total OUT Voltage Error and Full-Scale Accuracy are the sum of gain and offset voltage errors.
Note 6: Measured at IOUT = -500µA (RLOAD = 4kΩfor gain of +20V/V, RLOAD = 10kΩfor gain of +50V/V, RLOAD = 20kΩfor gain of
+100V/V).
Note 7: +6.25mV = 1/16 of +100mV full-scale voltage.
Note 8: The device will not experience phase reversal when overdriven.
Note 9: All comparator tests are done with VRS+ = +12V.
Note 10: VPULL-UP is defined as an externally applied voltage through a resistor to pull up the comparator output.
Note 11: VOS is extrapolated from the gain accuracy test.
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, VRESET = 0V, RLOAD= 1MΩ, TA= TMIN to TMAX, unless otherwise noted.
Typical values are at TA= +25°C.) (Note 1)
VCC = 28V, VPULL-UP = 5V (Note 10)
CONDITIONS
µA1Output High Leakage Current
UNITSMIN TYP MAXSYMBOLPARAMETER
V2.0VIH
RESET Input High Voltage
V0.8VIL
RESET Input Low Voltage
VIL = 0, VIH = 5.5V, VCC = 28V µA-0.5 0.5IIL, IIH
Logic Input Current
µs3tRPD
RESET Propagation Delay
µs1.5tRPW
Minimum RESET Pulse Width
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
_______________________________________________________________________________________
5
5
4
3
2
1
0
-1
-2
-3
-4
-5
2684 10121416182022242628
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
MAX4373 toc04
SUPPLY VOLTAGE (V)
OUTPUT ERROR (%)
AV = +50V/V
AV = +20V/V
AV = +100V/V
VSENSE = 6.25mV
-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
05025 75 100 125 150
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
MAX4373 toc05
VSENSE (mV)
OUTPUT ERROR (%)
AV = +50V/V
AV = +20V/V
AV = +100V/V
VCC = +5.5V
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
05025 75 100 125 150
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
MAX4373 toc06
VSENSE (mV)
OUTPUT ERROR (%)
AV = +50V/V
AV = +100V/V AV = +20V/V
0
1.0
0.5
2.0
1.5
2.5
3.0
0507525 100 125 150
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
MAX4373 toc07
VSENSE (mV)
OUTPUT ERROR (%)
AV = +50V/V
AV = +20V/V
AV = +100V/V
VCC = +28V
12
10
8
6
4
2
-2
0
2684 10121416182022242628
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
MAX4373 toc08
COMMON-MODE VOLTAGE (V)
OUTPUT ERROR (%)
AV = +50V/V
AV = +100V/V
AV = +20V/V
INPUT
OUTPUT
20µs/div
200mV
600mV
30mV
10mV
SMALL-SIGNAL PULSE RESPONSE
(AV = +20V/V)
MAX4373 toc09
INPUT
OUTPUT
20µs/div
500mV
1.5V
30mV
10mV
SMALL-SIGNAL PULSE RESPONSE
(AV = +50V/V)
MAX4373 toc10
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, RLOAD = 1MΩ, VRESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA= +25°C, unless
otherwise noted.)
INPUT
OUTPUT
20µs/div
1V
3V
30mV
10mV
SMALL-SIGNAL PULSE RESPONSE
(AV = +100V/V)
MAX4373 toc11
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, RLOAD = 1MΩ, VRESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA= +25°C, unless
otherwise noted.)
INPUT
OUTPUT
20µs/div
1V
3V
150mV
50mV
LARGE-SIGNAL PULSE RESPONSE
(AV = +20V/V)
MAX4373 toc12
INPUT
OUTPUT
20µs/div
2.5V
7.5V
150mV
50mV
LARGE-SIGNAL PULSE RESPONSE
(AV = +50V/V)
MAX4373 toc13
INPUT
OUTPUT
20µs/div
500mV
9.5V
95mV
5mV
LARGE-SIGNAL PULSE RESPONSE
(AV = +100V/V)
MAX4373 toc14
0
-10
-100
10 100 1k 10k 100k
COMMON-MODE REJECTION
vs. FREQUENCY
-50
-60
-70
-80
-90
MAX4373 toc15
FREQUENCY (Hz)
CMR (dB)
-40
-30
-20
0
-10
-100
10 100 1k 10k 100k
POWER-SUPPLY REJECTION
vs. FREQUENCY
-50
-60
-70
-80
-90
MAX4373 toc16
FREQUENCY (Hz)
PSR (dB)
-40
-30
-20
-5
-2
-3
-4
-1
0
1
2
3
4
5
1k 100k10k 1000k
SMALL-SIGNAL GAIN
vs. FREQUENCY
MAX4373 toc17
FREQUENCY (Hz)
GAIN (dB)
AV = +50V/V
AV = +100V/V
AV = +20V/V
5
4
-5
1k 10k 100k
LARGE-SIGNAL GAIN
vs. FREQUENCY
-3
-4
MAX4373 toc18
FREQUENCY (Hz)
GAIN (dB)
0
-1
-2
3
2
1
VIN = 100mVP-P (20, 50)
VIN = 50mVP-P (100)
AV = +50V/V
AV = +20V/V
AV = +100V/V
MAX4373/MAX4374/MAX4375
VCC
OUTPUT
100µs/div
0
2V
6V
0
POWER-UP DELAY
MAX4373 toc19
AV = +20V/V
OUTPUT
VCC
5V
5V
0
0
COMPARATOR POWER-UP DELAY
MAX4373 toc20
VCC = VPULL-UP
10µs/div
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
_______________________________________________________________________________________
7
590
593
592
591
594
595
596
597
598
599
600
0105 15202530
COMPARATOR TRIP POINT vs.
SUPPLY VOLTAGE
MAX4373 toc21
SUPPLY VOLTAGE (V)
TRIP POINT (mV)
INPUT
125mV/div
OUTPUT
2.5V/div
2µs/div
COMPARATOR PROPAGATION DELAY
MAX4373 toc22
VOD = 5mV
2
2.4
2.2
2.8
3.0
2.6
3.4
3.6
3.2
3.8
08040 120 16020 10060 140 180 200
COMPARATOR PROPAGATION DELAY
vs. OVERDRIVE VOLTAGE
MAX4373 toc24
OVERDRIVE VOLTAGE (mV)
PROGAGATION DELAY (µs)
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, RLOAD = 1MΩ, VRESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA= +25°C, unless
otherwise noted.)
0
2
1
4
3
6
5
7
-50 -10 10-30 30507090
COMPARATOR PROPAGATION DELAY
vs. TEMPERATURE
MAX4373 toc26
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
VOD = 5mV
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, RLOAD = 1MΩ, VRESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA= +25°C, unless
otherwise noted.)
0.8
1.2
1.0
1.6
1.4
1.8
2.0
010155 202530
COMPARATOR RESET VOLTAGE
vs. SUPPLY VOLTAGE
MAX4373 toc27
SUPPLY VOLTAGE (V)
RESET VOLTAGE (V)
0
20
10
50
40
30
80
70
60
90
0 0.6 0.80.2 0.4 1.0 1.2 1.4 1.6
COMPARATOR VOL vs. ISINK
MAX4373 toc28
ISINK (mA)
VOL (mV)
INPUT
OUTPUT
10µs/div
0
5V
750mV
250mV
COMPARATOR AC RESPONSE
MAX4373 toc31
0
0.2
0.6
0.4
0.8
1.0
-60 -20 0-40 20406080100
TOTAL OUTPUT ERROR
vs. TEMPERATURE
MAX4373 toc33
TEMPERATURE (°C)
TOTAL OUTPUT ERROR (%)
0
10
30
20
50
60
40
70
-60 -20 0-40 20406080100
SUPPLY CURRENT
vs. TEMPERATURE
MAX4373 toc32
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
MAX4374
MAX4375
MAX4373
VSENSE = 5mV
595
597
596
599
598
601
600
602
604
603
605
-60 -20 0-40 20406080100
COMPARATOR TRIP POINT
vs. TEMPERATURE
MAX4373 toc35
TEMPERATURE (°C)
COMPARATOR TRIP POINT (mV)
0
0.2
0.6
0.4
0.8
1.0
-60 -20 0-40 20406080100
GAIN ACCURACY
vs. TEMPERATURE
MAX4373 toc34
TEMPERATURE (°C)
GAIN ACCURACY (%)
AV = +20V/V, +50V/V
AV = +100V/V
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
_______________________________________________________________________________________ 9
FUNCTION
Detailed Description
The MAX4373 high-side current-sense supervisor fea-
tures a high-side current-sense amplifier, bandgap ref-
erence, and comparator with latching output to monitor
a supply for an overcurrent condition (Figure 1). The
latching output allows the comparator to shut down a
power supply without oscillations. The MAX4374/
MAX4375 offer an additional comparator to allow win-
dow detection of the current.
Current-Sense Amplifier
The internal current-sense amplifier features a 0V to
+28V input common-mode range that is independent of
the supply voltage. With this feature, the device can
monitor the output current of a battery in deep dis-
charge and also high-side current-sensing voltages
exceeding VCC.
The current-sense amplifier is also suitable for low-side
current sensing. However, the total output voltage error
will increase when VRS+ falls below 2V, as shown in
the
Electrical Characteristics
and
Typical Operating
Characteristics
.
Pin Description
RS-RS+
OUT
CIN2
GND
CIN1
LOAD
VIN = 0 TO 28V
VCC
RESET
0.6V
BANDGAP
REFERENCE
RSENSE
+ VSENSE -
VPULL-UP
(UP TO 5V) R2
R1 R4
R5
VPULL-UP
(UP TO 5V)
R6
MAX4374
(MAX4375)
R3 COUT1
COUT2
CURRENT-
SENSE
AMPLIFIER
+
-
+(-)
-(+)
Figure 1. Functional Diagram
FUNCTIONNAME
11 VCC
2 2 OUT
PIN
3 3 CIN1
— 4 CIN2
— 7 COUT2
6 8 COUT1
5 6 RESET
45GND
— — N.C.
810 RS+
7 9 RS-
Supply Voltage Input
1
2
4
5
10
11
8
7
3, 6, 9, 12
14
13
MAX4374/MAX4375
Voltage Output. VOUT is proportional to VSENSE (VRS+ - VRS-).
MAX4373
Comparator Input 1. Positive input of an internal comparator. The nega-
tive terminal is connected to a 0.6V internal reference.
Comparator Input 2. Terminal of a second internal comparator. The pos-
itive terminal for the MAX4374 and the negative terminal for the
MAX4375. The other terminal is connected to a 0.6V internal reference.
Open-Drain Comparator Output. Output of the second unlatched inter-
nal comparator.
Open-Drain Comparator Output. Latching output of the comparator con-
trolled by CIN1. Connect RESET to GND to disable the latch.
Reset Input. Resets the output latch of the comparator at CIN1.
µMAX
Ground
µMAX/SO SO
No Connection. Not internally connected.
Power Connection to the External Sense Resistor
Load-Side Connection for the External Sense Resistor
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
10 ______________________________________________________________________________________
Internal Comparator(s)
The MAX4373/MAX4374/MAX4375 contain an open-
drain output comparator for current limiting. The com-
parator’s negative terminal is connected to the internal
600mV reference. The positive terminal is accessible at
CIN1. When RESET is high, the internal latch is active,
and once CIN1 rises above 600mV, the output latches
into the open state. Pulsing RESET low for 1.5µs resets
the latch, and holding RESET low makes the latch
transparent. See
RESET at Power-Up
section
The MAX4374/MAX4375 contain an additional open-
drain comparator. The negative terminal of the
MAX4374’s additional comparator and the positive ter-
minal of the MAX4375’s additional comparator are con-
nected to the internal 600mV reference as shown in
Figure 1. The positive terminal of the MAX4374’s addi-
tional comparator and the negative terminal of the
MAX4375’s additional comparator are accessible at
CIN2.
___________Applications Information
Recommended Component Values
Ideally, the maximum load current will develop the full-
scale sense voltage across the current-sense resistor.
Choose the gain version needed to yield the maximum
output voltage required for the application:
where VSENSE is the full-scale sense voltage, 150mV for
gains of +20V/V and +50V/V or 100mV for a gain of
+100V/V. AVis the gain of the device. The minimum
supply voltage is VOUT + 0.25V. Note that the output for
the gain of +100V/V is internally clamped at 12V.
Calculate the maximum value for RSENSE so that the
differential voltage across RS+ and RS- does not
exceed the full-scale sense voltage:
Choose the highest value resistance possible to maxi-
mize VSENSE and thus minimize total output error.
In applications monitoring high current, ensure that
RSENSE is able to dissipate its own I2R loss. If the resis-
tor’s power dissipation is exceeded, its value may drift
or it may fail altogether, causing a differential voltage
across the terminals in excess of the absolute maxi-
mum ratings. Use resistors specified for current-sens-
ing applications.
Overcurrent Protection Circuit
The overcurrent protection circuit, shown in Figure 2,
uses the MAX4373 to control an external P-channel
MOSFET. The MOSFET controlled by the MAX4373
opens the current path under overload conditions. The
latched output of the MAX4373’s comparator prevents
the circuit from oscillating, and the pushbutton resets
the current path after an overcurrent condition.
Window Detection Circuit
Figure 3 shows a simple circuit suitable for window
detection. Let IOVER be the minimum load current
(ILOAD) required to cause a low state at COUT2, and let
IUNDER be the maximum load current required to cause
a high state at COUT1:
where AVis the gain of the device and VREF is the inter-
nal reference voltage (0.6V typ).
Connect COUT1 and COUT2; the resulting comparator
output will be high when the current is inside the cur-
rent window and low when the current is outside the
window. The window is defined as load currents less
than IOVER and greater than IUNDER.
RS-RS+
OUT
CIN1
LOAD
MAX4373
GND
COUT1
RESET
PUSHBUTTON
VCC
2.7V TO 5.5V
R
C
Figure 2. MAX4373 Overcurrent Protection Circuit
VVA
OUT SENSE V
=×
RV
I
SENSE MAX
LOAD
SENSE MAX
()
()
=
IV
RA
RR
R
and
IV
RA
RR
R
UNDER REF
SENSE V
OVER REF
SENSE V
=+
⎛
⎝
⎜⎞
⎠
⎟
=+
⎛
⎝
⎜⎞
⎠
⎟
×
×
45
5
12
2
Power-Supply Bypassing
It is recommended that VCC be bypassed to GND with
at least a 0.1µF ceramic capacitor to isolate the IC from
supply voltage transients. It is possible that plugging
in/out a battery or AC adapter/charger could cause
large, fast line transients (>5V/µs) at VCC. The simplest
solution is to run VCC from a better regulated supply
(+5V for example), since VCC and RS+ (or RS-) do not
have to be connected together.
For high-speed VCC transients, another solution is to
add a resistor in series with the VCC pin and a 0.1µF
capacitor to create an RC time constant to slow the rise
time of the transient. Since these current-sense ampli-
fiers consume less than 100µA, even a 2.5kΩresistor
only drops an extra 250mV at VCC. For most applica-
tions with fast transients, 1kΩin conjunction with a
0.1µF bypass capacitor works well.
RESET
at Power-Up
The RESET pin is used to control the latch function of
comparator 1. Holding RESET low (<0.8V) makes the
latch transparent and COUT1 will respond to changes
at CIN1, above and below the internal 600mV reference
threshold voltage. When RESET is high (>2.0V), once
CIN1 rises above 600mV, COUT1 latches into the
open-drain OFF state and remains in this state even if
CIN1 drops below 600mV. Pulsing RESET low for at
least 1.5µs resets the latch.
There is no internal circuitry to control the reset function
during power-up. To prevent false latching, RESET
must be held low until the VCC power has risen above
the 2.7V minimum operating supply voltage. This is
easily accomplished when RESET is driven under µC or
logic gate control. However, if RESET is to be always
connected high, add an RC between VCC, RESET and
GND (see Figure 2). Note that RESET cannot exceed
VCC + 0.3V or +12V, whichever is less.
The following formula can be used to determine the
appropriate RC value.
where T is the maximum time for VCC to reach 2.7V and
0.8V is the maximum RESET logic low voltage. For
example, a 470kΩresistor and 0.22µF capacitor will
keep RESET low during a power-up time of up to 36ms.
A faster power-up time is also safe with the calculated
R and C since the capacitor will have even less time to
charge.
RC T
VV V
T
=−
()
=
ln . /( . . ) .2 7 2 7 0 8 0 3514
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
______________________________________________________________________________________ 11
RS-RS+
OUT
CIN1
CIN2
LOAD
VCC = 2.7V TO 28V
VIN = 0 TO 28V
MAX4375
GND
VCC
GND R5
R4
RSENSE
+ VSENSE -
R3
COUT1
R2
R1
COUT2
ILOAD
RESET
VPULL-UP
(UP TO 5V)
Figure 3. MAX4375 Window Detector
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
12 ______________________________________________________________________________________
___________________Chip Information
SUBSTRATE CONNECTED TO GND
Ordering Information (continued)
PART TEMP RANGE PIN-
PACKAGE
GAIN
(V/V)
MAX4374TEUB+ -40°C to +85°C 10 µMAX +20
MAX4374TESD+ -40°C to +85°C 14 SO +20
MAX4374FEUB+ -40°C to +85°C 10 µMAX +50
MAX4374FESD+ -40°C to +85°C 14 SO +50
MAX4374HEUB+ -40°C to +85°C 10 µMAX +100
MAX4374HESD+ -40°C to +85°C 14 SO +100
MAX4375TEUB+ -40°C to +85°C 10 µMAX +20
MAX4375TESD+ -40°C to +85°C 14 SO +20
MAX4375FEUB+ -40°C to +85°C 10 µMAX +50
MAX4375FESD+ -40°C to +85°C 14 SO +50
MAX4375HEUB+ -40°C to +85°C 10 µMAX +100
MAX4375HESD+ -40°C to +85°C 14 SO +100
1
2
3
4
5
10
9
8
7
6
14
13
12
11
10
9
8
1
2
3
4
5
6
7
1
2
8
7
3
4
6
5
µMAX SO
µMAX/SO
RS+
++
+
RS-
COUT1
COUT2
CIN2
CIN1
OUT
VCC
GND
RS+
RS-
N.C.
COUT1
CIN1
N.C.
OUT
VCC
COUT2
N.C.
GND
N.C.
CIN2
COUT1
GND
RS+
RS-
OUT
CIN1
VCC
TOP VIEW
MAX4374
MAX4375
MAX4374
MAX4375
MAX4373
RESET RESET RESET
Pin Configurations
+
Denotes a lead(Pb)-free/RoHS-compliant package.
Package Information
(For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a "+", "#", or "-"
in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
DOCUMENT
NO.
LAND
PATTERN NO.
8 SOIC S8+2 21-0041 90-0096
8 µMAX U8+1 21-0036 90-0092
10 µMAX U10+2 21-0061 90-0330
14 SOIC S14+1 21-0041 90-0096
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
13
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
3 6/10 Clarified 0V to 2V is not a high-accuracy range for the device, added lead-free
options and soldering temperature 1, 2, 12
41/11 Clarified VRS+ conditions in Electrical Characteristics table 2
