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19-2048; Rev 0; 4/01
Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier
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 (-40C to +125C) 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. o Three Gain Versions Available +20V/V (MAX4073T) +50V/V (MAX4073F) +100V/V (MAX4073H) o 1.0% Full-Scale Accuracy o 500A Supply Current o Wide 1.8MHz Bandwidth o +3V to +28V Operating Supply o Wide +2V to +28V Common-Mode Range Independent of Supply Voltage o Automotive Temperature Range (-40C to +125C) o Available in Space-Saving 5-Pin SC70 Package
Features
o Low-Cost, Compact, Current-Sense Solution
MAX4073T/F/H
Typical Operating Circuit
+2V TO +28V VSENSE RSENSE +3V TO +28V 0.1F MAX4073T/F/H A/D CONVERTER OUT GND LOAD/ BATTERY RS+ VCC RSILOAD
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
Pin Configurations appear at end of data sheet.
Ordering Information
PART MAX4073TAXK-T MAX4073TAUT-T MAX4073FAXK-T MAX4073FAUT-T MAX4073HAXK-T MAX4073HAUT-T TEMP. RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C PIN-PACKAGE 5 SC70-5 6 SOT23-6 5 SC70-5 6 SOT23-6 5 SC70-5 6 SOT23-6 GAIN (V/V) 20 20 50 50 100 100 TOP MARK ACM AAUE ACN AAUF ACO AAUG
________________________________________________________________ Maxim Integrated Products
1
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier MAX4073T/F/H
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 = +70C) 5-pin SC70 (derate 2.27mW/C above +70C) ............200mW 6-pin SOT23 (derate 8.7mW/C above +70C)............696mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = +25C.) (Note 1)
PARAMETER Operating Voltage Range Common-Mode Input Range Common-Mode Rejection Supply Current Leakage Current Input Bias Current Full-Scale Sense Voltage SYMBOL VCC VCMR CMR ICC IRS+/IRSIRS+ IRSVSENSE VSENSE = (VRS+ - VRS-) VSENSE = 100mV, VCC = 12V, VRS+ = 2V VSENSE = 100mV, VCC = 12V, VRS+ = 12V, TA = +25oC VSENSE = 100mV, VCC = 12V, VRS+ = 12V, TA = TMIN to TMAX VSENSE = 100mV, VCC = 28V, VRS+ = 28V, TA = +25oC VSENSE = 100mV, VCC = 28V, VRS+ = 28V, TA = TMIN to TMAX VSENSE = 6.25mV (Note 5); VCC = 12V, VRS+ = 12V Extrapolated Input Offset Voltage OUT High Voltage VOS (VCC - VOH) VCC = VRS+ = 12V, VSENSE > 10mV VSENSE = 150mV MAX4073T, VCC = 3V MAX4073F, VCC = 7.5V MAX4073H, VCC = 15V 0.8 1.2 V 7.5 1.0 mV 1.0 (Note 2) (Note 3) VSENSE = 100mV, VCC = 12V VCC = 28V VCC = 0, VRS+ = 28V CONDITIONS MIN 3 2 90 0.5 0.05 20 40 150 1.0 1.0 5.0 7.0 % 5.0 8.5 1.2 1 60 120 TYP MAX 28 28 UNITS V V dB mA A A mV
Total OUT Voltage Error (Note 4)
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(VRS+ = +2V to +28V, VSENSE = (VRS+ - VRS-) = 0, VCC = +3V to +28V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MAX4073T, VSENSE = 100mV VCC = 12V, VRS+ = 12V, CLOAD = 5pF MAX4073F, VSENSE = 100mV MAX4073H, VSENSE = 100mV MAX4073T/F/H VSENSE = 6.25mV (Note 5) MAX4073T Gain AV MAX4073F MAX4073H VCC = 12V, TA = +25C VRS+ = 12V, VSENSE = 10mV to 150mV, TA = TMIN to TMAX MAX4073T/F VCC = 12V, TA = +25C VRS+ = 12V, VSENSE = 10mV to 100mV, TA = TMIN to TMAX MAX4073H OUT Settling Time to 1% of Final Value Output Resistance Power-Supply Rejection Ratio Power-Up Time (Note 6) Saturation Recovery Time (Note 7) ROUT VSENSE = 60mV, MAX4073T PSRR VCC = 3V to 28V VSENSE = 24mV, MAX4073F VSENSE = 12mV, MAX4073H CLOAD = 5pF, VSENSE = 100mV VCC = 12V, VRS+ = 12V, CLOAD = 5pF 70 70 70 VCC = 12V VRS+ = 12V CLOAD = 5pF VSENSE = 6.25mV to 100mV VSENSE = 100mV to 6.25mV MIN TYP 1.8 1.7 1.6 600 20 50 100 1.0 4.5 V/V kHz MHz MAX UNITS
MAX4073T/F/H
Bandwidth
BW
Gain Accuracy
AV
6.5 % 1.0 4.5 6.5 400 ns 800 12 78 85 90 5 5 s s dB k
Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7:
All devices are 100% production tested at TA = +25C. 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.
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier MAX4073T/F/H
Typical Operating Characteristics
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4073 toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4073 toc02
SUPPLY CURRENT vs. TEMPERATURE
VSENSE = 0 VCC = +28V
MAX4073 toc03
0.53 0.52 0.51 SUPPLY CURRENT (mA) 0.50 0.49 0.48 0.47 0.46 0.45 0.44 0.43 0 5 10 15 20 25 VSENSE = 6.25mV MAX4073T MAX4073F MAX4073H
1.5 1.4 1.3 SUPPLY CURRENT (mA) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 VSENSE = 100mV MAX4073T MAX4073F MAX4073H
0.7 0.6 SUPPLY CURRENT (mA) 0.5 0.4 0.3 0.2 0.1 0
30
0
5
10
15
20
25
30
-50
-25
0
25
50
75
100
125
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
SUPPLY CURRENT vs. VRS+ VOLTAGE
MAX4073 toc04
SUPPLY CURRENT vs. VRS+ VOLTAGE
MAX4073 toc05
OUTPUT HIGH VOLTAGE (VCC - VOH) vs. TEMPERATURE
0.9 0.8 0.7 VCC - VOH (V) 0.6 0.5 0.4 0.3 VSENSE = 150mV
MAX4073 toc06
0.54 VSENSE = 6.25mV 0.53 SUPPLY CURRENT (mA) 0.52 0.51 0.50 0.49 0.48 0.47 0 5 10 15 VRS+ (V) 20 25 MAX4073T MAX4073F MAX4073H
1.60 1.50 1.40 SUPPLY CURRENT (mA) 1.30 1.20 1.10 1.00 0.90 0.80 0.70 0.60 MAX4073T MAX4073F VSENSE = 100mV MAX4073H
1.0
0.2 0.1 0
30
0
5
10
15 VRS+ (V)
20
25
30
-50
-25
0
25
50
75
100
125
TEMPERATURE (C)
TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE
MAX 4073 toc07
TOTAL OUTPUT ERROR vs. SUPPLY VOLTAGE
VSENSE = 6.25mV
MAX4073 toc08
TOTAL OUTPUT ERROR vs. COMMON-MODE VOLTAGE
0.5 TOTAL OUTPUT ERROR (%) 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0
MAX4073 toc09
1.0 0.8 TOTAL OUTPUT ERROR (%) 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 5 10 15 20 25 MAX4073T MAX4073H VSENSE = 100mV MAX4073F
2.0 1.5 TOTAL OUTPUT ERROR (%) 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0
1.0
30
0
5
10
15
20
25
30
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25C, unless otherwise noted.)
TOTAL OUTPUT ERROR vs. TEMPERATURE
MAX4073 toc10
MAX4073T/F/H
GAIN ACCURACY vs. TEMPERATURE
VSENSE = (10mV - 100mV) 1.5 GAIN ACCURACY (%) 1.0 GAIN (dB) 0.5 0 -0.5 -1.0 -1.5 -2.0 -50 -25 0 75 50 TEMPERATURE (C) 25 100 125
MAX4073 toc11
SMALL-SIGNAL GAIN vs. FREQUENCY
40 35 30 25 20 15 10 5 0 0.1 1 10 100 FREQUENCY (kHz) 1000 10,000 MAX4073H MAX4073F MAX4073T
MAX4073 toc12
1.0 0.8 TOTAL OUTPUT ERROR (%) 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 -50 -25 0 25 50 75 VCC = +28V VCC = +12V
2.0
45
100 125 150
TEMPERATURE (C)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX4073H 90 80 PSRR (dB) 70 60 50 40 30 20 0.1 1 10 FREQUENCY (kHz) 100 1000 OUT 50mV/div MAX4073F MAX4073T VSENSE 2.5mV/div
MAX4073 toc13
MAX4073T SMALL-SIGNAL TRANSIENT RESPONSE
100
MAX4073 toc14
100mV
95mV
2V
1.9V
1s/div
MAX4073F SMALL-SIGNAL TRANSIENT RESPONSE
MAX4073H SMALL-SIGNAL TRANSIENT RESPONSE
100mV
MAX4073 toc15
MAX4073 toc16
100mV VSENSE 2.5mV/div
VSENSE 2.5mV/div 95mV
95mV
5V OUT 125mV/div 4.75V 1s/div OUT 250mV/div
10V
9.5V
1s/div
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier MAX4073T/F/H
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = +12V, VSENSE = 100mV, CL = 5pF, TA = +25C, unless otherwise noted.) MAX4073T LARGE-SIGNAL TRANSIENT RESPONSE
MAX4073 toc17
MAX4073F LARGE-SIGNAL TRANSIENT RESPONSE
MAX4073 toc18
100mV VSENSE 45mV/div 6.25mV VSENSE 45mV/div
100mV
6.25mV
2V OUT 0.9V/div 0.120V OUT 2.35V/div
5V
0.3V
1s/div
1s/div
MAX4073H LARGE-SIGNAL TRANSIENT RESPONSE
MAX4073 toc19
MAX4073T OVERDRIVE RESPONSE
VCC = +3V 100mV
MAX4073 toc20
250mV VSENSE 100mV/div
VSENSE 45mV/div 6.25mV
50mV
10V OUT 4.7V/div 0.6V OUT 600mV/div
VOH
1V
1s/div
1s/div
MAX4073T START-UP DELAY
VCC = 0 to +4V
MAX4073 toc21
4V VCC 2V/div 0
2V OUT 1V/div 0
1s/div
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier
Pin Description
PIN SOT23-6 1, 2 3 4 5 6 SC70-5 2 3 4 5 1 NAME GND VCC RS+ RSOUT Ground Supply Voltage Input. Bypass to GND with a 0.1F capacitor. Power-Side Connection to the External Sense Resistor Load-Side Connection to the External Sense Resistor Voltage Output. VOUT is proportional to VSENSE. Output impedance is approximately 12k. FUNCTION
MAX4073T/F/H
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, , to give IRGD = IRG1. Solving IRGD = (ILOAD)(RSENSE) / RG1. Assuming infinite output impedance, VOUT = (IRGD) (RGD). Substituting in for IRGD and rearranging, VOUT = (RGD / RG1)(RSENSE ILOAD). The parts gain equals 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.
VSOURCE +2V TO +28V RS+ IRG1 +3V TO +28V VCC RG1 RSENSE
ILOAD TO LOAD/BATTERY RSRG2
A1
MAX4073T/F/H
CURRENT MIRROR IRGD RGD = 12k GND OUT VOUT
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
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
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier MAX4073T/F/H
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 0.3in COPPER RSENSE 0.1in COPPER LOAD/BATTERY
+
VSENSE RS+ RSVCC
_
0.3in COPPER
+3V TO +28V 0.1F
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 30m/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 5m) 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.
MAX4073T OUT
GND
Figure 2. MAX4073T Connections Showing Use of PC Board
VIN
LOW-COST SWITCHING REGULATOR
+2V TO +28V
VSENSE RSENSE
ILOAD
+3V TO +28V 0.1F
Output Impedance
The output of the MAX4073 is a current source driving a 12k 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: RLOAD %ERROR = 100 - 1 12k + RLOAD where RLOAD is the external load applied to OUT.
RS+ VCC
RS-
MAX4073T/F/H OUT GND LOAD/ BATTERY
Figure 3. Current Source
Current Source Circuit
Figure 3 shows a block diagram using the MAX4073 with a switching regulator to make a current source.
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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 (m) GAIN 20 0.1 1000 50 100 20 1 100 50 100 20 5 20 50 100 20 10 10 50 100 FULL-SCALE OUTPUT VOLTAGE (FULL-SCALE VSENSE = 100mV) VOUT (V) 2.0 5.0 10.0 2.0 5.0 10.0 2.0 5.0 10.0 2.0 5.0 10.0
Pin Configurations
TOP VIEW
OUT 1 5 RSGND 1 6 OUT
GND 2
MAX4073T/F/H
GND 2
MAX4073T/F/H
5
RS-
VCC 3
4
RS+
VCC 3
4
RS+
SC70-5
SOT23-6
Chip Information
TRANSISTOR COUNT: 187 PROCESS: Bipolar
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Low-Cost, SC70, Voltage-Output, High-Side Current-Sense Amplifier MAX4073T/F/H
Package Information
SC70, 5L.EPS
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
6LSOT.EPS

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