EVALUATION KIT AVAILABLE
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
General Description
Benefits and Features
The MAX4373/MAX4374/MAX4375 low-cost, micropower, high-side current-sense supervisors contain a highside 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-detection 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 integration, resulting in a simple and compact currentsense solution.
The MAX4373/MAX4374/MAX4375 operate from a single +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.
• Integrated Current-Sensing Solution Simplifies High-
Applications
Notebook Computers
•
•
•
•
Side Current Monitoring
• Current-Sense Amplifier plus Internal Comparator
and Bandgap Reference with Improved Accuracy
• 1mV (max) Input Offset Voltage
• 2% (max) Full-Scale Accuracy
• Internal Bandgap Reference (±1.6% Accuracy)
High Accuracy +2V to +28V Common-Mode Range,
Functional Down to 0V, Independent of Supply
Voltage Ensures Current Monitoring Even In Deep
Discharge of Battery Pack
Low Power Consumption Extends Battery Life
• 50µA Supply Current
• Single +2.7V to +28V Operating Supply
Latching Comparator Output Eliminates Oscillation
Three Gain Versions (+20V/V, +50V/V,
+100V/V) Support Different Size Battery Packs
Ordering Information
PART
TEMP RANGE
PINPACKAGE
MAX4373TEUA+
-40°C to +85°C
8 µMAX
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
Typical Operating Circuit
VIN = 0 TO 28V
RSENSE
Power-Management Systems
Precision Current Sources
ILOAD
+ VSENSE -
Cell Phones
General-System/Board-Level Current Monitoring
+20
MAX4373HESA+ -40°C to +85°C 8 SO
+100
+Denotes a lead(Pb)-free/RoHS-compliant package.
Ordering Information continued at end of data sheet.
Portable/Battery-Powered Systems
Smart Battery Packs/Chargers
RS+
VCC = 2.7V TO 28V
LOAD/
BATTERY
RS-
VCC
C1
0.1µF
MAX4373
OUT
VPULL-UP
(UP TO 5V)
R1
R3
CIN
COUT
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.
19-1630; Rev 5; 5/15
GAIN
(V/V)
R2
RESET
GND
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Absolute Maximum Ratings
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
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
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
(Note 2)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VCC
2.7
28
V
Common-Mode Input Range
(Note 3)
VCMR
0
28
V
Common-Mode Rejection
CMR
Supply Current
Leakage Current
ICC
IRS+
IRS-
Input Offset Voltage
Total OUT Voltage Error
(Note 5)
85
VRS+ > 2V, VSENSE = 5mV
50
100
µA
±0.015
±0.5
µA
IRS+, IRS- VCC = 0V, VRS+ = 28V
Input Bias Current
Full-Scale Sense Voltage
(Note 4)
VRS+ > 2V
VSENSE
VOS
VOUT
VRS+ > 2V
0
2.5
VRS+ ≤ 2V
-25
2.0
VRS+ > 2V
0
4
VRS+ ≤ 2V
-50
Gain = +20V/V, +50V/V, VRS+ = 12V
150
170
Gain = +100V/V, VRS+ = 12V
100
120
VCC = VRS+ = 12V
(Note 11)
VSENSE =
100mV
(Note 6)
TA = +25°C
VCC = 12V,
VRS+ = 12V
TA = +25°C
VCC = 28V,
VRS+ = 28V
TA = +25°C
0.1
±2
±0.35
±2
±3
±5.0
IOUT = 100µA
8.5
OUT Voltage High
VCC VOH
VCC = 2.7V, IOUT = -500µA, VRS+ = 12V
%
±5.0
2.5
VCC = 2.7V,
VRS+ = 12V
mV
±3
IOUT = 10µA
VOUT
1
±0.30
TA = TMIN to TMAX
OUT Voltage Low
mV
2
TA = TMIN to TMAX
VSENSE = 6.25mV, VCC = 12V,
VRS+ = 12V (Note 7)
µA
4
TA = TMIN to TMAX
VCC = 12V, VRS+ = 0.1V
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dB
65
0.25
mV
V
Maxim Integrated | 2
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Electrical Characteristics (continued)
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Note 1)
PARAMETER
-3dB Bandwidth
SYMBOL
BW
CONDITIONS
VRS+ = 12V,
VCC = 12V,
CLOAD = 10pF
MIN
VSENSE = 100mV,
Gain = +20V/V
200
VSENSE = 100mV,
Gain = +50V/V
120
VSENSE = 100mV,
Gain = +100V/V
110
VSENSE = 6.25mV
Gain Accuracy
AV
ΔAV
OUT Settling Time to 1% of
Final Value
Capacitive Load Stability
MAX
UNITS
kHz
50
MAX437_T
Gain
TYP
+20
MAX437_F
+50
MAX437_H
+100
VSENSE =
20mV to 150mV;
VCC = 12V; VRS+ =
12V; Gain = 20, 50
TA = +25°C
VSENSE =
20mV to 100mV,
VCC = 12V, VRS+ =
12V, Gain = 100
TA = +25°C
Gain = +20V/V,
VCC = 12V,
VRS+ = 12V,
CLOAD = 10pF
VSENSE = 6.25mV to
100mV
20
VSENSE = 100mV to
6.25mV
20
±0.3
TA = -40°C to +85°C
V/V
±1.7
±2.7
%
±0.3
TA = -40°C to +85°C
±2.7
µs
No sustained oscillations
OUT Output Resistance
ROUT
VSENSE = 100mV
Power-Supply Rejection
PSR
VOUT = 2V, VRS+ > 2V
±1.7
72
1000
pF
1.5
Ω
87
dB
Power-Up Time to 1% of Final
Value
VSENSE = 100mV, CLOAD = 10pF,
VCC = 12V, VRS+ = 12V
0.5
ms
Saturation Recovery Time
(Note 8)
VCC = 12V, VRS+ = 12V, CLOAD = 10pF
0.1
ms
COMPARATOR (Note 9)
Comparator Threshold
VTH
TA = +25°C
590
TA = TMIN to TMAX
586
Comparator Hysteresis
Input Bias Current
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610
614
-9
IB
±2.2
CL = 10pF, RL = 10kΩ pull-up to 5V,
5mV of overdrive
Propagation Delay
Output Low Voltage
600
VOL
ISINK = 1mA
mV
mV
±15
4
nA
µs
0.6
V
Maxim Integrated | 3
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Electrical Characteristics (continued)
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0V, V RESET = 0V, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Output High Leakage Current
MIN
CONDITIONS
TYP
MAX
UNITS
1
µA
VCC = 28V, VPULL-UP = 5V (Note 10)
RESET Input High Voltage
VIH
RESET Input Low Voltage
VIL
2.0
V
-0.5
V
0.5
µA
Logic Input Current
IIL, IIH
Minimum RESET Pulse Width
tRPW
1.5
µs
RESET Propagation Delay
tRPD
3
µs
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
VIL = 0, VIH = 5.5V, VCC = 28V
0.8
All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Guaranteed by PSR test.
Guaranteed by OUT Voltage Error test.
Guaranteed by Gain Accuracy test. Output voltage is internally clamped not to exceed 12V.
Total OUT Voltage Error and Full-Scale Accuracy are the sum of gain and offset voltage errors.
Measured at IOUT = -500µA (RLOAD = 4kΩ for gain of +20V/V, RLOAD = 10kΩ for gain of +50V/V, RLOAD = 20kΩ for gain of
+100V/V).
+6.25mV = 1/16 of +100mV full-scale voltage.
The device will not experience phase reversal when overdriven.
All comparator tests are done with VRS+ = +12V.
VPULL-UP is defined as an externally applied voltage through a resistor to pull up the comparator output.
VOS is extrapolated from the gain accuracy test.
Typical Operating Characteristics
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
30
20
50
1.0
49
48
47
MAX4373
5
10
15
20
SUPPLY VOLTAGE (V)
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AV = +20V/V
-0.5
VSENSE = 100mV
-2.0
44
0
25
30
AV = +50V/V
0
VSENSE = 5mV
0
AV = +100V/V
-1.5
45
VSENSE = 5mV
0.5
-1.0
46
10
1.5
MAX4374/MAX4375
OUTPUT ERROR (%)
MAX4373
MAX4373 toc03
51
SUPPLY CURRENT (μA)
50
2.0
MAX4373 toc02
MAX4374/MAX4375
SUPPLY CURRENT (μA)
52
MAX4373 toc01
60
40
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
0
5
10
15
20
25
COMMON-MODE VOLTAGE (V)
30
2 4 6 8 10 12 14 16 18 20 22 24 26 28
SUPPLY VOLTAGE (V)
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Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
TOTAL OUTPUT ERROR
TOTAL OUTPUT ERROR
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
vs. SENSE VOLTAGE
vs. SENSE VOLTAGE
2
1
AV = +20V/V
-2
-3
AV = +20V/V
-0.5
-1.0
AV = +50V/V
-2.0
-1.5
-2.5
25
SUPPLY VOLTAGE (V)
50
75
100
125
150
10
AV = +100V/V
AV = +50V/V
1.5
AV = +20V/V
125
150
AV = +50V/V
2
-2
AV = +20V/V
2 4 6 8 10 12 14 16 18 20 22 24 26 28
VSENSE (mV)
COMMON-MODE VOLTAGE (V)
SMALL-SIGNAL PULSE RESPONSE
(AV = +20V/V)
SMALL-SIGNAL PULSE RESPONSE
(AV = +50V/V)
INPUT
30mV
30mV
10mV
10mV
600mV
1.5V
3V
OUTPUT
INPUT
OUTPUT
MAX4373 toc11
10mV
200mV
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SMALL-SIGNAL PULSE RESPONSE
(AV = +100V/V)
MAX4373 toc10
MAX4373 toc09
30mV
150
4
0
100
125
6
0
75
100
AV = +100V/V
8
0.5
50
75
MAX4373 toc08
MAX4373 toc07
12
2.0
20μs/div
50
VSENSE (mV)
OUTPUT ERROR (%)
OUTPUT ERROR (%)
2.5
25
25
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
VCC = +28V
0
0
VSENSE (mV)
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
1.0
AV = +50V/V
-2.0
0
3.0
AV = +20V/V
0
-0.5
-1.0
2 4 6 8 10 12 14 16 18 20 22 24 26 28
AV = +100V/V
0.5
-1.5
VSENSE = 6.25mV
-5
1.0
INPUT
-4
AV = +100V/V
500mV
20μs/div
OUTPUT
0
-1
1.5
0.5
0
MAX4373 toc06
1.0
OUTPUT ERROR (%)
AV = +50V/V
VCC = +5.5V
OUTPUT ERROR (%)
OUTPUT ERROR (%)
AV = +100V/V
2.0
MAX4373 toc05
4
3
1.5
MAX4373 toc04
5
1V
20μs/div
Maxim Integrated | 5
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
LARGE-SIGNAL PULSE RESPONSE
(AV = +100V/V)
LARGE-SIGNAL PULSE RESPONSE
(AV = +50V/V)
LARGE-SIGNAL PULSE RESPONSE
(AV = +20V/V)
50mV
5mV
3V
7.5V
9.5V
2.5V
20μs/div
POWER-SUPPLY REJECTION
vs. FREQUENCY
COMMON-MODE REJECTION
vs. FREQUENCY
-20
-20
-30
-30
-40
-40
-50
-50
-60
-60
-70
-70
-80
-80
-90
-90
-100
-100
100
1k
10k
100k
1k
10k
SMALL-SIGNAL GAIN
vs. FREQUENCY
LARGE-SIGNAL GAIN
vs. FREQUENCY
2
3
2
AV = +20V/V
0
AV = +100V/V
-1
-2
-3
-3
-4
-4
-5
-5
100k
FREQUENCY (Hz)
1000k
AV = +50V/V
0
-2
10k
AV = +20V/V
1
GAIN (dB)
AV = +50V/V
VIN = 100mVP-P (20, 50)
VIN = 50mVP-P (100)
4
100k
MAX4373 toc18
5
MAX4373 toc17
3
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100
FREQUENCY (Hz)
4
GAIN (dB)
10
FREQUENCY (Hz)
5
1k
MAX4373 toc16
-10
PSR (dB)
CMR (dB)
0
MAX4373 toc15
0
-10
-1
500mV
20μs/div
20μs/div
1
OUTPUT
50mV
1V
10
95mV
INPUT
INPUT
150mV
OUTPUT
INPUT
150mV
OUTPUT
MAX4373 toc14
MAX4373 toc13
MAX4373 toc12
AV = +100V/V
1k
10k
100k
FREQUENCY (Hz)
Maxim Integrated | 6
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
POWER-UP DELAY
COMPARATOR POWER-UP DELAY
MAX4373 toc20
MAX4373 toc19
VCC = VPULL-UP
AV = +20V/V
5V
6V
VCC
VCC
0
0
2V
5V
OUTPUT
OUTPUT
0
0
100μs/div
10µs/div
COMPARATOR TRIP POINT vs.
SUPPLY VOLTAGE
598
597
MAX4373 toc22
599
TRIP POINT (mV)
COMPARATOR PROPAGATION DELAY
MAX4373 toc21
600
VOD = 5mV
INPUT
125mV/div
596
595
594
593
OUTPUT
2.5V/div
592
591
590
0
5
10
15
20
25
30
2μs/div
SUPPLY VOLTAGE (V)
COMPARATOR PROPAGATION DELAY
vs. TEMPERATURE
COMPARATOR PROPAGATION DELAY
vs. OVERDRIVE VOLTAGE
VOD = 5mV
6
PROPAGATION DELAY (μs)
3.4
3.2
3.0
2.8
2.6
MAX4373 toc26
3.6
PROGAGATION DELAY (μs)
7
MAX4373 toc24
3.8
5
4
3
2
2.4
1
2.2
0
2
0
20 40 60 80 100 120 140 160 180 200
OVERDRIVE VOLTAGE (mV)
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-50
-30
-10
10
30
50
70
90
TEMPERATURE (°C)
Maxim Integrated | 7
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0V, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)otherwise noted.)
COMPARATOR RESET VOLTAGE
vs. SUPPLY VOLTAGE
MAX4373 toc28
1.8
80
70
60
1.6
VOL (mV)
RESET VOLTAGE (V)
COMPARATOR VOL vs. ISINK
90
MAX4373 toc27
2.0
1.4
50
40
1.2
30
20
1.0
10
0.8
0
5
10
15
20
25
30
0
0.2
0.4
0.6
SUPPLY VOLTAGE (V)
0.8
1.0
1.2
1.4
1.6
ISINK (mA)
TOTAL OUTPUT ERROR
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
MAX4373 toc31
750mV
250mV
5V
OUTPUT
60
SUPPLY CURRENT (μA)
INPUT
1.0
MAX4373 toc32
70
MAX4374
MAX4375
TOTAL OUTPUT ERROR (%)
COMPARATOR AC RESPONSE
50
40
MAX4373
30
20
MAX4373 toc33
0
0.8
0.6
0.4
0.2
10
0
VSENSE = 5mV
0
0
-60
10μs/div
-40
-20
0
20
40
60
80
-60
100
-40
-20
40
60
80
100
AV = +20V/V, +50V/V
AV = +100V/V
0.4
0.2
MAX4373 toc35
0.8
605
604
COMPARATOR TRIP POINT (mV)
MAX4373 toc34
1.0
GAIN ACCURACY (%)
20
COMPARATOR TRIP POINT
vs. TEMPERATURE
GAIN ACCURACY
vs. TEMPERATURE
0.6
0
TEMPERATURE (°C)
TEMPERATURE (°C)
603
602
601
600
599
598
597
596
595
0
-60
-40
-20
0
20
40
TEMPERATURE (°C)
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60
80
100
-60
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
Maxim Integrated | 8
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Pin Description
PIN
NAME
FUNCTION
MAX4373
MAX4374/MAX4375
µMAX/SO
µMAX
SO
1
1
1
VCC
Supply Voltage Input
2
2
2
OUT
Voltage Output. VOUT is proportional to VSENSE (VRS+ - VRS-).
3
3
4
CIN1
Comparator Input 1. Positive input of an internal comparator. The negative terminal is connected to a 0.6V internal reference.
—
4
5
CIN2
Comparator Input 2. Terminal of a second internal comparator. The positive terminal for the MAX4374 and the negative terminal for the
MAX4375. The other terminal is connected to a 0.6V internal reference.
4
5
7
GND
Ground
5
6
8
RESET
Reset Input. Resets the output latch of the comparator at CIN1.
6
8
11
COUT1
Open-Drain Comparator Output. Latching output of the comparator controlled by CIN1. Connect RESET to GND to disable the latch.
—
7
10
COUT2
Open-Drain Comparator Output. Output of the second unlatched internal comparator.
7
9
13
RS-
Load-Side Connection for the External Sense Resistor
8
10
14
RS+
Power Connection to the External Sense Resistor
—
—
3, 6, 9, 12
N.C.
No Connection. Not internally connected.
FUNCTION
Detailed Description
+ VSENSE -
VIN = 0 TO 28V
RSENSE
RS+
LOAD
RS-
VCC
CURRENTSENSE
AMPLIFIER
VPULL-UP
(UP TO 5V)
R3
VPULL-UP
(UP TO 5V)
R6
COUT1
+
-
OUT
R1
+(-)
-(+)
0.6V
BANDGAP
REFERENCE
MAX4374
(MAX4375)
GND
Figure 1. Functional Diagram
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Current-Sense Amplifier
R2
RESET
COUT2
R4
CIN1
The MAX4373 high-side current-sense supervisor features a high-side current-sense amplifier, bandgap reference, 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 window detection of the current.
CIN2
R5
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 discharge 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.
Maxim Integrated | 9
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
Internal Comparator(s)
The MAX4373/MAX4374/MAX4375 contain an opendrain output comparator for current limiting. The comparator’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 opendrain comparator. The negative terminal of the
MAX4374’s additional comparator and the positive terminal of the MAX4375’s additional comparator are connected to the internal 600mV reference as shown in
Figure 1. The positive terminal of the MAX4374’s additional comparator and the negative terminal of the
MAX4375’s additional comparator are accessible at
CIN2.
Applications Information
LOAD
RS+
RS-
2.7V TO 5.5V
OUT
COUT1
VCC
MAX4373
R
CIN1
RESET
PUSHBUTTON
C
GND
Figure 2. MAX4373 Overcurrent Protection Circuit
Recommended Component Values
Ideally, the maximum load current will develop the fullscale sense voltage across the current-sense resistor.
VOUT = VSENSE × AV
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. AV is 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.
RSENSE(MAX) =
VSENSE(MAX)
ILOAD
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 maximize 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 resistor’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 maximum ratings. Use resistors specified for current-sensing applications.
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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 I OVER be the minimum load current
IUNDER =
⎛ R4 + R5 ⎞
VREF
⎜
⎟
RSENSE × AV ⎝
R5 ⎠
and
IOVER =
⎛ R1 + R2 ⎞
VREF
⎜
⎟
RSENSE × AV ⎝ R2 ⎠
(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 AV is the gain of the device and VREF is the internal reference voltage (0.6V typ).
Connect COUT1 and COUT2; the resulting comparator
output will be high when the current is inside the current window and low when the current is outside the
window. The window is defined as load currents less
than IOVER and greater than IUNDER.
Maxim Integrated | 10
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
RESET at Power-Up
ILOAD
+ VSENSE VIN = 0 TO 28V
RSENSE
LOAD
RS+
VCC = 2.7V TO 28V
RS-
VCC
OUT
VPULL-UP
(UP TO 5V)
R1
MAX4375
R3
CIN2
COUT1
R4
R2
CIN1
COUT2
GND
RESET
R5
GND
The RESET pin is used to control the latch function of
comparator 1. Holding RESET low (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.
Figure 3. MAX4375 Window Detector
RC =
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 amplifiers consume less than 100µA, even a 2.5kΩ resistor
only drops an extra 250mV at VCC. For most applications with fast transients, 1kΩ in conjunction with a
0.1µF bypass capacitor works well.
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T
T
=
ln(2.7V /(2.7V − 0.8V)) 0.3514
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 470kΩ resistor 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.
Maxim Integrated | 11
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Pin Configurations
TOP VIEW
+
+
+
VCC 1
OUT 2
CIN1
8
MAX4373
7
RS+
RS-
3
6
COUT1
GND 4
5
RESET
VCC 1
OUT 2
CIN1 3
CIN2 4
GND 5
14 RS+
OUT 2
13 RS-
10 RS+
N.C. 3
9
RS-
CIN1 4
8
COUT1
CIN2 5
10 COUT2
7
COUT2
N.C. 6
9
N.C.
RESET
GND 7
8
RESET
6
µMAX
µMAX/SO
Ordering Information (continued)
PART
TEMP RANGE
PINPACKAGE
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
+Denotes a lead(Pb)-free/RoHS-compliant package.
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MAX4374
MAX4375
VCC 1
GAIN
(V/V)
12 N.C.
MAX4374
MAX4375
11 COUT1
SO
Chip Information
SUBSTRATE CONNECTED TO GND
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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
CODE
OUTLINE
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
PACKAGE
TYPE
Maxim Integrated | 12
Low-Cost, Micropower, High-Side
Current-Sense Amplifier +
Comparator + Reference ICs
MAX4373/MAX4374/MAX4375
Revision History
REVISION
NUMBER
REVISION
DATE
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
4
1/11
Clarified VRS+ conditions in Electrical Characteristics table
2
5
5/15
Added the Benefits and Features section
1
DESCRIPTION
1, 2, 12
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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