Maxim MAX4073FAXK-T Low-cost, sc70, voltage-output, high-side current-sense amplifier Datasheet

19-2048; Rev 0; 4/01
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
Features
♦ Low-Cost, Compact, Current-Sense Solution
♦ Three Gain Versions Available
+20V/V (MAX4073T)
+50V/V (MAX4073F)
+100V/V (MAX4073H)
♦ ±1.0% Full-Scale Accuracy
♦ 500µA Supply Current
♦ Wide 1.8MHz Bandwidth
♦ +3V to +28V Operating Supply
♦ Wide +2V to +28V Common-Mode Range
Independent of Supply Voltage
♦ Automotive Temperature Range (-40°C to +125°C)
♦ Available in Space-Saving 5-Pin SC70 Package
Typical Operating Circuit
RSENSE
+3V TO +28V
Applications
Cell Phones
Notebook Computers
Portable/Battery-Powered Systems
Smart Battery Packs/Chargers
PDAs
Power Management Systems
PA Bias Control
General System/Board-Level Current Monitoring
Precision Current Sources
ILOAD
VSENSE
+2V TO +28V
RS+
VCC
RS-
0.1µF
MAX4073T/F/H
A/D
CONVERTER
LOAD/
BATTERY
OUT
GND
Pin Configurations appear at end of data sheet.
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX4073TAXK-T
-40°C to +125°C
5 SC70-5
GAIN (V/V)
20
TOP MARK
ACM
MAX4073TAUT-T
-40°C to +125°C
6 SOT23-6
20
AAUE
MAX4073FAXK-T
-40°C to +125°C
5 SC70-5
50
ACN
MAX4073FAUT-T
-40°C to +125°C
6 SOT23-6
50
AAUF
MAX4073HAXK-T
-40°C to +125°C
5 SC70-5
100
ACO
MAX4073HAUT-T
-40°C to +125°C
6 SOT23-6
100
AAUG
________________________________________________________________ Maxim Integrated Products
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.
1
MAX4073T/F/H
General Description
The MAX4073 low-cost, high-side current-sense amplifier features a voltage output that eliminates the need
for gain-setting resistors making it ideal for cell phones,
notebook computers, PDAs, and other systems where
current monitoring is crucial. High-side current monitoring does not interfere with the ground path of the
battery charger making the MAX4073 particularly useful
in battery-powered systems. The input common-mode
range of +2V to +28V is independent of the supply voltage. The MAX4073’s wide 1.8MHz bandwidth makes it
suitable for use inside battery-charger control loops.
The combination of three gain versions and a selectable external-sense resistor sets the full-scale current
reading. The MAX4073 offers a high level of integration, resulting in a simple and compact current-sense
solution.
The MAX4073 operates from a +3V to +28V single supply and draws only 0.5mA of supply current. This
device is specified over the automotive operating temperature range (-40°C to +125°C) and is available in a
space-saving 5-pin SC70 package (half the size of the
SOT23).
For a similar device in a 6-pin SOT23 with a wider common-mode voltage range (0 to +28V), see the
MAX4173 data sheet.
MAX4073T/F/H
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
ABSOLUTE MAXIMUM RATINGS
VCC to GND ............................................................-0.3V to +30V
RS+, RS- to GND....................................................-0.3V to +30V
OUT to GND ...............................................-0.3V to (VCC + 0.3V)
Output Short-Circuit to GND ......................................Continuous
Differential Input Voltage (VRS+ - VRS-) .................................±5V
Current Into Any Pin..........................................................±20mA
Continuous Power Dissipation (TA = +70°C)
5-pin SC70 (derate 2.27mW/°C above +70°C) ............200mW
6-pin SOT23 (derate 8.7mW/°C above +70°C)............696mW
Operating Temperature Range .........................-40°C to +125°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
(VRS+ = +2V to +28V, VSENSE = (VRS+ - VRS-) = 0, VCC = +3V to +28V, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
VCC
(Note 2)
3
28
Common-Mode Input Range
VCMR
(Note 3)
2
28
Common-Mode Rejection
CMR
VSENSE = 100mV, VCC = 12V
Supply Current
Leakage Current
Input Bias Current
Full-Scale Sense Voltage
ICC
90
VCC = 28V
0.5
1.2
mA
VCC = 0, VRS+ = 28V
0.05
1
µA
IRS+
20
60
IRS-
40
120
IRS+/IRS-
VSENSE
VSENSE = (VRS+ - VRS-)
150
VSENSE = 100mV, VCC = 12V, VRS+ = 2V
±1.0
VSENSE = 100mV, VCC = 12V,
VRS+ = 12V, TA = +25oC
±1.0
VSENSE = 100mV, VCC = 12V,
VRS+ = 12V, TA = TMIN to TMAX
Total OUT Voltage Error (Note 4)
VSENSE = 100mV, VCC = 28V,
VRS+ = 28V, TA = +25oC
VSENSE = 6.25mV (Note 5); VCC = 12V,
VRS+ = 12V
OUT High Voltage
VOS
(VCC - VOH)
VCC = VRS+ = 12V, VSENSE > 10mV
VSENSE =
150mV
mV
±5.0
%
±1.0
±5.0
±8.5
±7.5
1.0
mV
MAX4073T, VCC = 3V
MAX4073F, VCC = 7.5V
0.8
MAX4073H, VCC = 15V
2
µA
±7.0
VSENSE = 100mV, VCC = 28V,
VRS+ = 28V, TA = TMIN to TMAX
Extrapolated Input Offset Voltage
V
dB
_______________________________________________________________________________________
1.2
V
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
(VRS+ = +2V to +28V, VSENSE = (VRS+ - VRS-) = 0, VCC = +3V to +28V, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 1)
PARAMETER
Bandwidth
SYMBOL
BW
CONDITIONS
VCC = 12V,
VRS+ = 12V,
CLOAD = 5pF
MIN
MAX4073T,
VSENSE = 100mV
1.8
MAX4073F,
VSENSE = 100mV
1.7
MAX4073H,
VSENSE = 100mV
1.6
MAX4073T/F/H
VSENSE = 6.25mV (Note 5)
600
MAX4073T
AV
Gain
∆AV
Gain Accuracy
MAX4073F
50
MAX4073H
100
VCC = 12V,
TA = +25°C
VRS+ = 12V,
VSENSE = 10mV
to 150mV,
TA = TMIN to TMAX
MAX4073T/F
VCC = 12V
VRS+ = 12V
CLOAD = 5pF
Output Resistance
ROUT
Power-Supply Rejection Ratio
PSRR
±1.0
UNITS
MHz
kHz
V/V
±4.5
±6.5
%
±1.0
±4.5
±6.5
VSENSE = 6.25mV to
100mV
400
VSENSE = 100mV to
6.25mV
800
ns
12
VCC = 3V to 28V
MAX
20
VCC = 12V,
TA = +25°C
VRS+ = 12V,
VSENSE = 10mV
to 100mV,
TA = TMIN to TMAX
MAX4073H
OUT Settling Time to 1% of Final
Value
TYP
VSENSE = 60mV, MAX4073T
70
78
VSENSE = 24mV, MAX4073F
70
85
VSENSE = 12mV, MAX4073H
70
90
kΩ
dB
Power-Up Time (Note 6)
CLOAD = 5pF, VSENSE = 100mV
5
µs
Saturation Recovery Time
(Note 7)
VCC = 12V, VRS+ = 12V,
CLOAD = 5pF
5
µs
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Inferred from PSRR test.
Inferred from OUT Voltage Error test.
Total OUT Voltage Error is the sum of the gain and offset errors.
6.25mV = 1/16 of 100mV full-scale sense voltage.
Output settles to within 1% of final value.
The device will not experience phase reversal when overdriven.
_______________________________________________________________________________________
3
MAX4073T/F/H
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
0.49
0.48
0.47
MAX4073T
0.46
1.1
1.0
MAX4073F
0.8
0.7
0.45
MAX4073T
0.6
VSENSE = 6.25mV
10
15
20
25
5
10
15
20
25
30
-50
0
25
50
75
100
SUPPLY CURRENT vs.
VRS+ VOLTAGE
OUTPUT HIGH VOLTAGE
(VCC - VOH) vs. TEMPERATURE
0.51
MAX4073F
0.49
VSENSE = 100mV
1.50
MAX4073H
1.40
MAX4073T
0.48
0.8
1.30
0.7
1.20
1.10
MAX4073F
1.00
0.90
15
20
25
0.5
0.4
0.2
0.1
0
0
30
0.6
0.3
MAX4073T
0.60
10
VSENSE = 150mV
0.9
0.70
0.47
5
10
15
20
25
30
-50
-25
0
25
50
75
100
VRS+ (V)
VRS+ (V)
TEMPERATURE (°C)
TOTAL OUTPUT ERROR vs.
SUPPLY VOLTAGE
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
MAX4073H
0.2
0
-0.2
-0.4
MAX4073T
-0.6
VSENSE = 6.25mV
1.5
1.0
0.5
0
-0.5
-1.0
-1.0
10
15
20
SUPPLY VOLTAGE (V)
25
30
0.5
0
-0.5
-1.0
-1.5
-2.0
-3.0
-2.0
5
125
-2.5
-1.5
-0.8
1.0
TOTAL OUTPUT ERROR (%)
0.6
0.4
2.0
MAX4073 toc08
MAX4073F
TOTAL OUTPUT ERROR (%)
VSENSE = 100mV
MAX 4073 toc07
1.0
125
1.0
VCC - VOH (V)
0.52
0.50
1.60
MAX4073 toc05
MAX4073H
0
-25
SUPPLY CURRENT vs.
VRS+ VOLTAGE
0.80
4
0.1
TEMPERATURE (˚C)
0.53
0.8
0.2
SUPPLY VOLTAGE (V)
VSENSE = 6.25mV
5
0.3
SUPPLY VOLTAGE (V)
0.54
0
0.4
0
0
30
SUPPLY CURRENT (mA)
5
MAX4073 toc04
0
0.5
VSENSE = 100mV
0.5
0.43
VSENSE = 0
VCC = +28V
0.6
MAX4073 toc09
0.44
SUPPLY CURRENT (mA)
1.2
0.9
0.7
MAX4073 toc06
MAX4073F
MAX4073H
1.3
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
0.51
1.4
SUPPLY CURRENT (mA)
MAX4073H
0.50
1.5
MAX4073 toc02
0.52
MAX4073 toc01
0.53
SUPPLY CURRENT vs.
TEMPERATURE
MAX4073 toc03
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
TOTAL OUTPUT ERROR (%)
MAX4073T/F/H
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
0
5
10
15
20
SUPPLY VOLTAGE (V)
25
30
0
5
10
15
20
25
COMMON-MODE VOLTAGE (V)
_______________________________________________________________________________________
30
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25°C, unless otherwise noted.)
1.5
GAIN ACCURACY (%)
VCC = +12V
0.4
0.2
0
-0.2
VCC = +28V
-0.4
0
-0.5
5
-2.0
-25
0
25
50
75
0
-50
100 125 150
-25
TEMPERATURE (°C)
0
25
75
50
TEMPERATURE (°C)
100
125
0.1
1
10
100
FREQUENCY (kHz)
1000
10,000
MAX4073T SMALL-SIGNAL
TRANSIENT RESPONSE
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
MAX4073 toc14
MAX4073 toc13
100
MAX4073H
90
100mV
MAX4073F
80
PSRR (dB)
20
10
-1.5
-50
MAX4073T
25
15
-0.6
-1.0
MAX4073F
35
30
0.5
-1.0
-0.8
MAX4073H
40
1.0
MAX4073 toc12
VSENSE = (10mV - 100mV)
GAIN (dB)
0.6
45
MAX4073 toc11
0.8
TOTAL OUTPUT ERROR (%)
2.0
MAX4073 toc10
1.0
SMALL-SIGNAL GAIN vs.
FREQUENCY
GAIN ACCURACY
vs. TEMPERATURE
TOTAL OUTPUT ERROR
vs. TEMPERATURE
VSENSE
2.5mV/div
MAX4073T
70
95mV
60
2V
50
40
OUT
50mV/div
30
1.9V
20
0.1
1
10
100
1µs/div
1000
FREQUENCY (kHz)
MAX4073H SMALL-SIGNAL
TRANSIENT RESPONSE
MAX4073F SMALL-SIGNAL
TRANSIENT RESPONSE
MAX4073 toc16
MAX4073 toc15
100mV
100mV
VSENSE
2.5mV/div
VSENSE
2.5mV/div
95mV
95mV
5V
10V
OUT
125mV/div
OUT
250mV/div
9.5V
4.75V
1µs/div
1µs/div
_______________________________________________________________________________________
5
MAX4073T/F/H
Typical Operating Characteristics (continued)
MAX4073T/F/H
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25°C, unless otherwise noted.)
MAX4073T LARGE-SIGNAL
TRANSIENT RESPONSE
MAX4073F LARGE-SIGNAL
TRANSIENT RESPONSE
MAX4073 toc17
MAX4073 toc18
100mV
100mV
VSENSE
45mV/div
VSENSE
45mV/div
6.25mV
6.25mV
2V
5V
OUT
0.9V/div
OUT
2.35V/div
0.120V
0.3V
1µs/div
1µs/div
MAX4073H LARGE-SIGNAL
TRANSIENT RESPONSE
MAX4073T
OVERDRIVE RESPONSE
MAX4073 toc19
MAX4073 toc20
VCC = +3V
250mV
100mV
VSENSE
100mV/div
VSENSE
45mV/div
6.25mV
50mV
10V
VOH
OUT
4.7V/div
OUT
600mV/div
0.6V
1V
1µs/div
1µs/div
MAX4073T
START-UP DELAY
MAX4073 toc21
VCC = 0 to +4V
4V
VCC
2V/div
0
2V
OUT
1V/div
0
1µs/div
6
_______________________________________________________________________________________
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
PIN
NAME
FUNCTION
SOT23-6
1, 2
SC70-5
2
GND
Ground
3
3
VCC
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
4
4
RS+
Power-Side Connection to the External Sense Resistor
5
5
RS-
Load-Side Connection to the External Sense Resistor
6
1
OUT
Voltage Output. VOUT is proportional to VSENSE. Output impedance is approximately
12kΩ.
Detailed Description
The MAX4073 high-side current-sense amplifier features a +2V to +28V input common-mode range that is
independent of supply voltage. This feature allows the
monitoring of current out of a battery as low as +2V and
also enables high-side current sensing at voltages
greater than the supply voltage (VCC).
The MAX4073 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 = 20V/V for MAX4073T, GAIN =
50V/V for MAX4073F, and GAIN = 100V/V for MAX4073H.
Set the full-scale output range by selecting RSENSE and
the appropriate gain version of the MAX4073.
Applications Information
Recommended Component Values
The MAX4073 senses a wide variety of currents with
different sense resistor values. Table 1 lists common
resistor values for typical operation of the MAX4073.
Choosing RSENSE
To measure lower currents more accurately, use a
large value for RSENSE. The larger value develops a
RSENSE
VSOURCE
+2V TO +28V
+3V TO +28V
VCC
ILOAD
TO LOAD/BATTERY
RS+
IRG1
RS-
RG1
RG2
A1
MAX4073T/F/H
OUT
CURRENT
MIRROR
VOUT
IRGD
RGD = 12kΩ
GND
Figure 1. Functional Diagram
higher-sense voltage that reduces offset voltage errors
of the internal op amp. Typical sense voltages range
between 10mV and 150mV.
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 (±5V).
If ISENSE has a large high-frequency component, minimize the inductance of RSENSE. Wire-wound resistors
have the highest inductance, metal-film resistors are
_______________________________________________________________________________________
7
MAX4073T/F/H
Pin Description
MAX4073T/F/H
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
somewhat better, and low-inductance metal-film resistors are best suited for these applications.
For VSENSE = 100mV, full-scale output voltage can be
2V, 5V, or 10V depending on the gain. For proper operation, ensure VCC exceeds the full-scale output voltage
by 1.2V (see Output High Voltage (V CC - V OH ) vs.
Temperature in the Typical Operating Characteristics).
INPUT
LOAD/BATTERY
RSENSE
0.3in COPPER
0.1in COPPER
0.3in COPPER
_
+
VSENSE
RS+
RS-
+3V TO +28V
VCC
0.1µF
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 MAX4073T (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.
Output Impedance
The output of the MAX4073 is a current source driving a
12kΩ resistance. Resistive loading added to OUT
reduces the output gain of the MAX4073. 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
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:
MAX4073T
OUT
GND
Figure 2. MAX4073T Connections Showing Use of PC Board
VIN
LOW-COST
SWITCHING
REGULATOR
ILOAD
VSENSE
+2V TO +28V
RSENSE
+3V TO +28V
RS+
VCC
RS-
0.1µF
MAX4073T/F/H
LOAD/
BATTERY
OUT
GND
Figure 3. Current Source


RLOAD
%ERROR = 100 
− 1
 12kΩ + RLOAD

where RLOAD is the external load applied to OUT.
Current Source Circuit
Figure 3 shows a block diagram using the MAX4073
with a switching regulator to make a current source.
8
_______________________________________________________________________________________
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
MAX4073T/F/H
Table 1. Recommended Component Values
FULL-SCALE LOAD CURRENT
ILOAD (A)
CURRENT-SENSE RESISTOR
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
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
Pin Configurations
TOP VIEW
OUT
1
GND 2
5
RS-
MAX4073T/F/H
VCC 3
GND 1
GND 2
4
RS+
SC70-5
MAX4073T/F/H
VCC 3
6
OUT
5
RS-
4
RS+
SOT23-6
Chip Information
TRANSISTOR COUNT: 187
PROCESS: Bipolar
_______________________________________________________________________________________
9
Low-Cost, SC70, Voltage-Output,
High-Side Current-Sense Amplifier
6LSOT.EPS
SC70, 5L.EPS
MAX4073T/F/H
Package Information
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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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