LE
AVAILAB
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
General Description
The MAX4173 low-cost, precision, high-side currentsense amplifier is available in a tiny SOT23-6 package.
It features a voltage output that eliminates the need for
gain-setting resistors and it is ideal for today’s notebook
computers, cell phones, and other systems where 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 input common-mode range of 0 to +28V is
independent of the supply voltage and ensures that the
current-sense feedback remains viable even when connected to a battery in deep discharge. The MAX4173’s
wide 1.7MHz bandwidth makes it suitable for use inside
battery charger control loops.
The combination of three gain versions and a userselectable external sense resistor sets the full-scale
current reading. This feature offers a high level of integration, resulting in a simple and compact currentsense solution.
The MAX4173 operates from a single +3V to +28V supply, typically draws only 420µA of supply current over
the extended operating temperature range (-40°C to
+85°C), and is offered in the space-saving SOT23
package.
Features
o Low-Cost, Compact Current-Sense Solution
o High Accuracy +2V to +28V Common-Mode
Range, Functional Down to 0V, Independent of
Supply Voltage
o Three Gain Versions Available
+20V/V (MAX4173T)
+50V/V (MAX4173F)
+100V/V (MAX4173H)
o ±0.5% Full-Scale Accuracy
o ±3mV Input Offset Voltage (MAX4173T)
o Wide 1.7MHz Bandwidth (MAX4173T)
o 420µA Supply Current
o Available in Space-Saving SOT23 Package
Typical Operating Circuit
RSENSE
Applications
Notebook Computers
Portable/Battery-Powered Systems
Smart Battery Packs/Chargers
Functional Diagrams
Cell Phones
Power-Management Systems
General System/Board-Level Current Monitoring
PA Bias Control
Precision Current Sources
ILOAD
VSENSE
0 TO +28V
RS+
VCC
+3V TO +28V
RS-
0.1µF
MAX4173T/F/H
A/D
CONVERTER
LOAD/
BATTERY
OUT
GND
Ordering Information
PART
GAIN (V/V)
TEMP RANGE
PIN-PACKAGE
MAX4173TEUT+T
20
-40°C to +85°C
6 SOT23
MAX4173TESA+
20
-40°C to +85°C
8 SO
MAX4173FEUT+T
50
-40°C to +85°C
6 SOT23
MAX4173FESA+
50
-40°C to +85°C
8 SO
MAX4173HEUT+T
100
-40°C to +85°C
6 SOT23
-40°C to +85°C
8 SO
MAX4173HESA+
100
Pin Configurations appear at end of data sheet.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Functional
Diagrams
continued at end of data sheet.
T = Tape and
reel.
UCSP
is
a
trademark
of
Maxim
Integrated
Pin Configurations appear
at end
of dataProducts,
sheet. Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
SOT TOP MARK
AABN
—
AABO
—
AABP
—
19-1434; Rev 5; 4/11
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
ABSOLUTE MAXIMUM RATINGS
VCC, RS+, RS- to GND .......................................... -0.3V to +30V
OUT to GND .............................................. -0.3V to (VCC + 0.3V)
Output Short-Circuit to VCC or GND ......................... Continuous
Differential Input Voltage (VRS+ - VRS-) ............................. ±0.3V
Current into Any Pin......................................................... ±20mA
Continuous Power Dissipation (TA = +70°C)
8-Pin SO (derate 5.88mW/°C above +70°C)............... 471mW
SOT23-6 (derate 8.7mW/°C above +70°C)................. 696mW
Operating Temperature Range .......................... -40°C to +85°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
(VRS+ = 0 to +28V, VCC = +3V to +28V, VSENSE = 0V, TA = TMIN to TMAX, RLOAD = ∞ unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
SYMBOL
VCC
MAX
UNITS
Guaranteed by PSR test
CONDITIONS
3
28
V
0
28
V
Common-Mode Input Range
VCMR
(Note 2)
Common-Mode Rejection
CMR
VRS+ > +2.0V
Supply Current
Leakage Current
ICC
IRS+, IRSIRS+
Input Bias Current
IRSFull-Scale Sense Voltage
VSENSE
Total OUT Voltage Error
(Note 3)
Out High Voltage (Note 5)
OUT Low Voltage
2
(VCC - VOH)
VOL
MIN
TYP
90
dB
VRS+ > +2.0V, VCC > 12V
0.42
1.0
mA
VCC = 0V, VRS+ = 28V
0.3
3
µA
VRS+ > +2.0V
0
50
VRS+ ≤ +2.0V
-350
50
VRS+ > +2.0V
0
100
VRS+ ≤ +2.0V
-700
100
VSENSE = VRS+ - VRS-
150
VSENSE = +100mV, VCC = +12V, VRS+ = +12V
±0.5
5.75
VSENSE = +100mV, VCC = +12V, VRS+ = +12V,
TA = +25°C
0.5
3.25
VSENSE = +100mV, VCC = +28V, VRS+ = +28V
0.5
5.75
VSENSE = +100mV, VCC = +12V, VRS+ = +0.1V
-9
±24
VCC = +12V, VRS+ = +12V, VSENSE = +6.25mV
(Note 4)
±7.5
mV
MAX4173T, VCC = +3.0V, VRS+ = 28V,
VSENSE = 250mV
0.8
1.2
MAX4173F, VCC = +7.5V, VRS+ = 28V,
VSENSE = 250mV
0.8
1.2
MAX4173H, VCC = +15V, VRS+ = 28V,
VSENSE = 250mV
0.8
1.2
1.2
5
MAX4173TEUT,
TA = +25°C
VCC = +5V, VRS+ = 0.89V,
TA = -40°C to +85°C
VSENSE = 0mV
µA
%
V
mV
40
Maxim Integrated
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(VRS+ = 0 to +28V, VCC = +3V to +28V, VSENSE = 0V, TA = TMIN to TMAX, RLOAD = ∞ unless otherwise noted. Typical values are at
TA = +25°C.) (Note 1)
PARAMETER
Bandwidth
Gain
SYMBOL
BW
AV
∆AV
CONDITIONS
VRS+ = +12V,
VCC = +12V,
CLOAD = 5pF
MIN
TYP
MAX4173T,
VSENSE = +100mV
1.7
MAX4173F,
VSENSE = +100mV
1.4
MAX4173H,
VSENSE = +100mV
1.2
VSENSE = +6.25mV
(Note 4)
0.6
20
MAX4173F
50
MAX4173H
100
TA = +25°C
MAX4173H VSENSE =
+10mV to +100mV,
VCC = VRS+ = 12V
TA = +25°C
MAX4173TEUT,
VRS+ = 12V
TA = +25°C
0.5
TA = -40°C to +85°C
V/V
±2.5
4.0
%
Gain Accuracy
∆AV
Input Offset Voltage
(Note 6)
VOS
OUT Settling Time to 1% of
Final Value
OUT Output Resistance
Power-Supply Rejection
UNITS
MHz
MAX4173T
MAX4173T/F VSENSE =
+10mV to +150mV,
VCC = VRS+ = 12V
MAX
VCC = +12V, VRS+ = 12V,
CLOAD = 5pF
0.5
TA = -40°C to +85°C
4.0
0.3
TA = -40°C to +85°C
±3
±5
VSENSE = +6.25mV
to +100mV
400
VSENSE = +100mV
to +6.25mV
800
mV
ns
ROUT
PSR
±2.5
12
MAX4173T, VSENSE = 80mV, VRS+ ≥ +2V
60
84
MAX4173F, VSENSE = 32mV, VRS+ ≥ +2V
60
91
MAX4173H, VSENSE = 16mV, VRS+ ≥ +2V
60
95
kΩ
dB
Power-Up Time to 1% of
Final Value
VSENSE = +100mV, CLOAD = 5pF
10
µs
Saturation Recovery Time
VCC = +12V, VRS+ = 12V (Note 7)
10
µs
Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Note 2: Guaranteed by Total Output Voltage Error Test.
Note 3: Total OUT Voltage Error is the sum of gain and offset voltage errors.
Note 4: +6.25mV = 1/16 of +100mV full-scale voltage.
Note 5: VSENSE such that output stage is in saturation.
Note 6: VOS is extrapolated from the Gain Accuracy tests.
Note 7: The device does not experience phase reversal when overdriven.
Maxim Integrated
3
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Typical Operating Characteristics
(VCC = +12V, VRS+ = +12V, VSENSE = +100mV, TA = +25°C, unless otherwise noted.)
MAX4173H
400
MAX4173F
390
400
MAX4173F
350
300
MAX4173H
15
20
25
TOTAL OUTPUT ERROR vs.
SUPPLY VOLTAGE
MAX4173T
0
MAX4173H
-0.15
MAX4173F
-0.30
25
40
55
70
MAX4173 toc03
1.5
2.0
2.5
0
MAX4173F
-2
28
4
VCC = 28V
3
2
MAX4173H
1
0
MAX4173T
-1
15
20
25
MAX4173F
-2
0
30
5
10
15
20
25
30
-10
4
TOTAL OUTPUT ERROR (%)
-20
-30
-40
-50
-60
-70
-80
MAX4173H
2
MAX4173T
0
-2
MAX4173F
-4
1M
10M
200
0.8
MAX4173T
MAX4173H
0.4
0
-0.4
MAX4173F
-6
-0.8
-1.2
-10
-100
150
GAIN ACCURACY vs. TEMPERATURE
-8
-90
FREQUENCY (Hz)
100
1.2
MAX4173 toc08
6
MAX4173 toc07
0
100k
50
VSENSE (mV)
TOTAL OUTPUT ERROR vs.
COMMON-MODE VOLTAGE
POWER-SUPPLY REJECTION
vs. FREQUENCY
10k
0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
GAIN ACCURACY (%)
10
1k
1.0
TOTAL OUTPUT ERROR vs.
FULL-SCALE SENSE VOLTAGE
-6
100
0.5
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
MAX4173H
2
0
VSENSE = 6.25mV
-0.60
5
MAX4173H
VRS+ (V)
MAX4173T
VSENSE = 100mV
0
0.4
85
-4
-0.45
MAX4173F
MAX4173 toc09
0.15
10
4
TOTAL OUTPUT ERROR (%)
0.30
-5
6
MAX4173 toc04
0.45
MAX4173T
0.6
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
0.60
0.8
0
-50 -35 -20
30
TOTAL OUTPUT ERROR (%)
10
MAX4173 toc05
5
1.0
0.2
150
0
TOTAL OUTPUT ERROR (%)
1.2
200
370
PSR (dB)
MAX4173 toc02
MAX4173T
450
250
380
4
SUPPLY CURRENT vs. RS+ VOLTAGE
1.4
SUPPLY CURRENT (mA)
420
410
500
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
MAX4173 TOC01
MAX4173T
430
SUPPLY CURRENT vs. TEMPERATURE
550
MAX4173 toc06
SUPPLY CURRENT vs. SUPPLY VOLTAGE
440
0
5
10
15
20
25
COMMON-MODE VOLTAGE (V)
30
-50 -35 -20
-5
10
25
40
55
70
85
TEMPERATURE (°C)
Maxim Integrated
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = +12V, VSENSE = +100mV, TA = +25°C, unless otherwise noted.)
MAX4173 toc10
2.0
TOTAL OUTPUT ERROR (%)
1.5
1.0
CL = 5pF
MAX4173H
IN
(45mV/div)
MAX4173T
0.5
MAX4173 toc11
MAX4173T
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
TOTAL OUTPUT ERROR
vs. TEMPERATURE
100mV
6mV
0
2V
-0.5
MAX4173F
OUT
(500mV/div)
-1.0
0.120V
-1.5
-2.0
-50 -35 -20
-5
10
25
40
55
70
85
2µs/div
TEMPERATURE (°C)
CL = 5pF
IN
(45mV/div)
MAX4173 toc13
MAX4173H
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
MAX4173 toc12
MAX4173F
LARGE-SIGNAL TRANSIENT RESPONSE
(VSENSE = 6mV to 100mV)
CL = 5pF
100mV
6mV
IN
(45mV/div)
100mV
6mV
10V
5V
OUT
(2V/div)
OUT
(3V/div)
0.6V
0.3V
MAX4173T
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV TO 100mV)
MAX4173F
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV TO 100mV)
CL = 5pF
IN
(5mV/div)
MAX4173 toc16
2µs/div
MAX4173 toc14
2µs/div
CL = 5pF
100mV
95mV
IN
(5mV/div)
100mV
95mV
2.0V
5V
OUT
(50mV/div)
1.9V
OUT
(100mV/div)
4.75V
2µs/div
Maxim Integrated
2µs/div
5
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = +12V, VSENSE = +100mV, TA = +25°C, unless otherwise noted.)
MAX4173H
SMALL-SIGNAL TRANSIENT RESPONSE
(VSENSE = 95mV to 100mV)
CL = 5pF
IN
(5mV/div)
MAX4173 toc17
MAX4173 toc15
START-UP DELAY (VCC = 0 to 4V)
(VSENSE = 100mV)
100mV
95mV
4V
IN
(2V/div)
0V
2V
10V
OUT
(200mV/div)
OUT
(1V/div)
0V
9.5V
5µs/div
2µs/div
Pin Description
PIN
NAME
6
FUNCTION
SOT23
SO
1, 2
3
GND
Ground
3
1
VCC
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
4
8
RS+
Power-Side Connection to the External Sense Resistor
5
6
RS-
Load-Side Connection for the External Sense Resistor
6
4
OUT
Voltage Output. VOUT is proportional to VSENSE ( VRS+ - VRS- ). Output impedance is
approximately 12kΩ.
–
2, 5, 7
N.C.
No Connection. Not internally connected.
Maxim Integrated
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Detailed Description
The MAX4173 high-side current-sense amplifier features a 0 to +28V input common-mode range that is
independent of supply voltage. This feature allows the
monitoring of current out of a battery in deep discharge
and also enables high-side current sensing at voltages
greater than the supply voltage (VCC).
The MAX4173 operates as follows: Current from the
source flows through RSENSE to the load (Figure 1). Since
the internal-sense amplifier’s inverting input has high
impedance, negligible current flows through RG2
(neglecting the input bias current). Therefore, the
sense amplifier’s inverting-input voltage equals
VSOURCE - (ILOAD)(RSENSE). The amplifier’s open-loop
gain forces its noninverting input to the same voltage as
the inverting input. Therefore, the drop across RG1
equals (ILOAD)(RSENSE). Since IRG1 flows through RG1,
IRG1 = (ILOAD)(RSENSE) / RG1. The internal current mirror
multiplies I RG1 by a current gain factor, β, to give
IRGD = β · IRG1. Solving IRGD = β · (ILOAD)(RSENSE) /
RG1. Assuming infinite output impedance, VOUT = (IRGD)
(RGD). Substituting in for IRGD and rearranging, VOUT =
β · (RGD / RG1)(RSENSE · ILOAD). The parts gain equals
β · RGD / RG1. Therefore, VOUT = (GAIN) (RSENSE)
(ILOAD), where GAIN = 20 for MAX4173T, GAIN = 50 for
MAX4173F, and GAIN = 100 for MAX4173H.
RSENSE
VSOURCE
0 TO +28V
RS+
ILOAD
TO LOAD BATTERY
RS-
IRG1
+3V TO +28V
RG1
VCC
RG2
A1
OUT
IRGD
RGD = 12k
GND
Figure 1. Functional Diagram
Maxim Integrated
Applications Information
Recommended Component Values
The MAX4173 senses a wide variety of currents with
different sense resistor values. Table 1 lists common
resistor values for typical operation of the MAX4173.
Choosing RSENSE
To measure lower currents more accurately, use a high
value for RSENSE. The high value develops a higher
sense voltage that reduces offset voltage errors of the
internal op amp.
In applications monitoring very high currents, RSENSE
must be able to dissipate the I2R losses. If the resistor’s
rated 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.
If ISENSE has a large high-frequency component, minimize the inductance of RSENSE. Wire-wound resistors
have the highest inductance, metal-film resistors are
somewhat better, and low-inductance metal-film resistors are best suited for these applications.
Using a PCB Trace as RSENSE
If the cost of RSENSE is an issue and accuracy is not
critical, use the alternative solution shown in Figure 2.
This solution uses copper PC board traces to create a
sense resistor. The resistivity of a 0.1-inch-wide trace of
2-ounce copper is approximately 30mΩ/ft. The resistance-temperature coefficient of copper is fairly high
(approximately 0.4%/°C), so systems that experience a
wide temperature variance must compensate for this
effect. In addition, do not exceed the maximum power
dissipation of the copper trace.
For example, the MAX4173T (with a maximum load current of 10A and an RSENSE of 5mΩ) creates a full-scale
VSENSE of 50mV that yields a maximum VOUT of 1V.
RSENSE in this case requires about 2 inches of 0.1 inchwide copper trace.
MAX4173
CURRENT
MIRROR
Set the full-scale output range by selecting RSENSE and
the appropriate gain version of the MAX4173.
VOUT
Output Impedance
The output of the MAX4173 is a current source driving a
12kΩ resistance. Resistive loading added to OUT
reduces the output gain of the MAX4173. To minimize
output errors for most applications, connect OUT to a
high-impedance input stage. When output buffering is
required, choose an op amp with a common-mode
input range and an output voltage swing that includes
ground when operating with a single supply. The op
7
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Table 1. Recommended Component Values
FULL-SCALE LOAD CURRENT
ILOAD (A)
CURRENT-SENSE RESISTOR
Ω)
RSENSE (mΩ
GAIN
FULL-SCALE OUTPUT VOLTAGE
(FULL-SCALE VSENSE = 100mV)
VOUT (V)
20
2.0
0.1
1000
50
5.0
100
10.0
20
2.0
1
100
5
20
10
10
INPUT
0.1 in. COPPER
+
_
0.3 in. COPPER
VSENSE
RS-
RS+
5.0
10.0
20
2.0
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
LOAD/BATTERY
RSENSE
0.3 in. COPPER
50
100
VIN
+3V TO +28V
+3V TO +28V
VCC
0.1µF
ILOAD
VSENSE
LOW-COST 0 TO +28V
SWITCHING
REGULATOR
RSENSE
RS+
RS-
VCC
0.1µF
MAX4173
MAX4173T
OUT
LOAD/
BATTERY
OUT
GND
GND
Figure 2. MAX4173 Connections Showing Use of PC Board
Figure 3. Current Source
amp’s supply voltage range should be at least as high
as any voltage the system may encounter.
The percent error introduced by output loading is
determined with the following formula:
Figure 3 shows a block diagram using the MAX4173
with a switching regulator to make a current source.
Current Source Circuit
⎛
⎞
RLOAD
%ERROR = 100 ⎜
− 1⎟
⎝ 12kΩ + RLOAD
⎠
where RLOAD is the external load applied to OUT.
8
Maxim Integrated
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Pin Configurations
TOP VIEW
+
GND 1
GND 2
MAX4173
VCC 3
6
OUT
5
RS-
4
+
VCC 1
RS+
SOT23
8
RS+
7
N.C.
N.C.
2
GND
3
6
RS-
OUT 4
5
N.C.
MAX4173
SO
Package Information
For the latest package outline information and land patterns
(footprints), 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
OUTLINE
NO.
LAND
PATTERN NO.
8 SO
S8+4
21-0041
90-0096
6 SOT23
U6+2
21-0058
90-0175
Maxim Integrated
9
MAX4173
Low-Cost, SOT23, Voltage-Output,
High-Side Current-Sense Amplifier
Revision History
REVISION
NUMBER
REVISION
DATE
4
6/10
Clarified 0V to 2V is not a high-accuracy range for the device, added lead-free
options and soldering temperature
1, 2
5
4/11
Updated VRS+ conditions to synchronize with tested material
2, 3
DESCRIPTION
PAGES
CHANGED
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. 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.
10
© Maxim Integrated
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
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