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Low Cost, Voltage Output, High-Side, Current-Sense Amplifier ADM4073
FEATURES
Low cost, compact, current-sense solution Three available gain versions 20 V/V (ADM4073T) 50 V/V (ADM4073F) 100 V/V (ADM4073H) Typical 1.0% full-scale accuracy 500 A supply current Wide 1.8 MHz bandwidth 3 V to 28 V operating supply Wide 2 V to 28 V common-mode range Independent of supply voltage Operates from -40C to +125C Available in a 6-lead SOT-23 package Pin-to-pin compatibility with the MAX4073
FUNCTIONAL BLOCK DIAGRAM
2V TO 28V RS+ IRG1 RG1 RG2 ILOAD RSENSE RS- VOUT
3V TO 28V 0.1F
VCC
AV
ADM4073
CURRENT MIRROR IRGD GND RGD = 12k
05131-003
VOUT
APPLICATIONS
Cell phones, PDAs Notebook computers Portable/battery-powered systems Smart battery packs/chargers Automotive Power management systems PA bias control General system/board-level current monitoring Precision current sources
Figure 1.
APPLICATION DIAGRAM
2V TO 28V RSENSE VOUT
RS+ 3V TO 28V 0.1F VCC
RS-
OUT
ADC
ADM4073
GND
Figure 2.
GENERAL DESCRIPTION
The ADM4073 is a low cost, high-side, current-sense amplifier ideal for small portable applications such as cell phones, notebook computers, PDAs, and other systems where current monitoring is required. The device is available in three different gain models, eliminating the need for gain-setting resistors. Because the ground path is not interrupted, the ADM4073 is particularly useful in rechargeable battery-powered systems, while its wide 1.8 MHz bandwidth makes it suitable for use inside battery-charger control loops. The input common-mode range of 2 V to 28 V is independent of the supply voltage. The voltage on the output pin is determined by the current flowing through the selectable external sense resistor and the gain of the version selected. The operating range is 3 V to 28 V with a typical supply current of 500 A. The ADM4073 is available in a 6-lead SOT-23 package and is specified over the automotive operating temperature range (-40C to +125C).
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2006 Analog Devices, Inc. All rights reserved.
05131-001
ADM4073 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Functional Block Diagram .............................................................. 1 Application Diagram........................................................................ 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 Thermal Characteristics .............................................................. 4 ESD Caution...................................................................................4 Pin Configuration and Function Descriptions..............................5 Typical Performance Characteristics ..............................................6 Theory of Operation ...................................................................... 10 RSENSE............................................................................................. 10 Output (OUT)............................................................................. 10 Outline Dimensions ....................................................................... 11 Ordering Guide .......................................................................... 11
REVISION HISTORY
7/06--Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADM4073 SPECIFICATIONS
VRS+ = 2 V to 28 V, VSENSE = (VRS+ - VRS-) = 0, VCC = 3 V to 28 V, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = 25C. 1 Table 1.
Parameter POWER SUPPLY Operating Voltage Range, VCC Common-Mode Input Range, VCMR Common-Mode Input Rejection, CMR Supply Current, ICC Leakage Current, IRS+/IRS- Input Bias Current, IRS+ Input Bias Current, IRS- Full Scale Sense Voltage, VSENSE Total Out Voltage Error 2 Min 3 2 90 0.5 0.05 20 40 150 1 1.0 1.0 7.5 1.0 0.8 0.8 0.8 1.8 1.7 1.6 600 20 50 100 1.0 Typ Max 28 28 1.2 2 60 120 Unit V V dB mA A A A mV % % % % % % mV V V V MHz MHz MHz kHz V/V V/V V/V % % % % ns ns k dB dB dB s s Conditions Inferred from PSRR test Inferred OUT voltage error test VSENSE = 100 mV, VCC = 12 V VCC = 28 V VCC = 0 V, VRS+ = 28 V, TA = 85C
5.0 5.0 5.0 5.0
Extrapolated Input Offset Voltage, VOS Out High Voltage (VCC - VOH)
1.2 1.2 1.2
VSENSE = (VRS+ - VRS-) VSENSE = 100 mV, VCC = 12 V, VRS+ = 2 V VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, TA = +25C VSENSE = 100 mV, VCC = 12 V, VRS = 12V, TA = -40C to +125C VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = +25C VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = -40C to +125C VSENSE = 6.25 mV, 3 VCC = 12 V, VRS = 12 V VCC = VRS+ = 12 V, VSENSE > 10 mV VCC = 3 V, VSENSE = 150 mV (ADM4073T) VCC = 7.5 V, VSENSE = 150 mV (ADM4073F) VCC = 15 V, VSENSE = 150 mV (ADM4073H), TA = 25C VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T) VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073F) VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073H) VSENSE = 6.25 mV,3 VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T/F/H) ADM4073T ADM4073F ADM4073H VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V, TA = +25C (ADM4073T/F) VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V, TA = -40C to +125C (ADM4073T/F) VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, TA = +25C (ADM4073H) VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, TA = -40C to +125C (ADM4073H) VSENSE = 6.25 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF VSENSE = 100 mV to 6.25 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF VSENSE = 60 mV, VCC = 3 V to 28 V (ADM4073T) VSENSE = 24 mV, VCC = 3 V to 28 V (ADM4073F) VSENSE = 12 mV, VCC = 3 V to 28 V (ADM4073H) CLOAD = 5 pF, VSENSE = 100 mV CLOAD = 5 pF, VCC = 12 V, VRS+ = 12 V
DYNAMIC CHARACTERISTICS Bandwidth, BW
Gain, AV
Gain Accuracy, dAV
2.0 2.0
1.0
1.5 3.0
OUT Settling Time to 1% of Final Value Output Resistance, ROUT Power Supply Rejection Ratio, PSRR
Power-Up Time 4 Saturation Recovery Time 5
1 2
400 800 12 78 85 90 5 5
100% production tested at TA = 25C. Specifications over temperature limit are guaranteed by design. Total out voltage error is the sum of the gain and offset errors. 3 6.25 mV = 1/16th of 100 mV full-scale sense voltage. 4 Output settles to within 1% of final value. 5 The device does not experience phase reversal when overdriven.
Rev. 0 | Page 3 of 12
ADM4073 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter VCC to GND RS to GND OUT to GND OUT Short-Circuit to GND Differential Input Voltage (VRS+ - VRS-) Current into any Pin Storage Temperature Range Operating Temperature Range Lead Temperature, Soldering (10 sec) Junction Temperature Rating -0.3 V to +30 V -0.3 V to +30 V -0.3 V to (VCC + 0.3 V) Continuous 5 V 20 mA -65C to +125C -40C to +125C 300C 150C
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
THERMAL CHARACTERISTICS
JA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 3. Thermal Resistance
Package Type 6-Lead SOT-23 JA 169.5 Unit C/W
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. 0 | Page 4 of 12
ADM4073 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
ADM4073xWRJ
GND 1
6
OUT
TOP VIEW GND 2 (Not to Scale) 5 RS- VCC 3
4
RS+
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. 1, 2 3 4 5 6 Mnemonic GND VCC RS+ RS- OUT Description Chip Ground Pin. Chip Power Supply. Requires a 0.1F capacitor to ground. Power-Side Connection to the External Sense Resistor. Load-Side Connection to the External Sense Resistor. Voltage Output. VOUT is proportional to VSENSE. Output impedence is approximately 12 k.
Rev. 0 | Page 5 of 12
05131-002
ADM4073 TYPICAL PERFORMANCE CHARACTERISTICS
0.60 VSENSE = 6.25mV 0.55
SUPPLY CURRENT (mA) SUPPLY CURRENT (mA)
0.45 VSENSE = 6.25mV 0.43 ADM4073H 0.41 ADM4073T 0.39 ADM4073F 0.37
0.50 ADM4073H 0.45 ADM4073F 0.40 ADM4073T 0.35
05131-005
0
5
10
15
20
25
30
0
5
10
15 VRS+ (V)
20
25
30
SUPPLY VOLTAGE (V)
Figure 4. Supply Current vs. Supply Voltage (VSENSE = 6.25mV)
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 0 5 10 15 ADM4073T 20 25 30
05131-006
Figure 7. Supply Current vs. RS+ Voltage (VSENSE = 6.25 mV)
VSENSE = 100mV
1.5
ADM4073H
VSENSE = 100mV
SUPPLY CURRENT (mA)
1.3 ADM4073H 1.1
ADM4073F
0.9
ADM4073F
0.7
ADM4073T
0
5
10
15 VRS+ (V)
20
25
30
SUPPLY VOLTAGE (V)
Figure 5. Supply Current vs. Supply Voltage (VSENSE = 100 mV)
0.7 0.6 SUPPLY CURRENT (mA) 0.5 0.4 0.3 0.2 0.1 VSENSE = 0mV VCC = 28V TOTAL OUTPUT ERROR (%)
Figure 8. Supply Current vs. RS+ Voltage (VSENSE = 100 mV)
1.0 0.8 0.6 ADM4073F 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8
05131-007
VSENSE = 100mV
ADM4073T
ADM4073H
-25
0
25
50
75
100
125
150
0
5
10
15
20
25
30
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
Figure 6. Supply Current vs. Temperature
Figure 9. Total Output Error vs. Supply Voltage (VSENSE = 100 mV)
Rev. 0 | Page 6 of 12
05131-010
0 -50
-1.0
05131-009
0.5
05131-008
0.30
0.35
ADM4073
1.0 0.8
TOTAL OUTPUT ERROR (%)
2.0 VSENSE = 6.25mV 1.5 1.0
0.6
GAIN ACCURACY (%)
05131-011
0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 0 5 10 15 20 25 30 ADM4073H ADM4073T ADM4073F
0.5 0 -0.5 -1.0 -1.5 -2.0 -50
-25
0
25
50
75
100
125
150
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
Figure 10. Total Output Error vs. Supply Voltage (VSENSE = 6.25 mV)
1.0 0.5 TOTAL OUTPUT ERROR (%) 0 VCC - VOH (V) -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 ADM4073T ADM4073F ADM4073H 1.0 0.8 0.6 0.4 1.4 1.2
Figure 13. Gain Accuracy vs. Temperature
ADM4073H
ADM4073F
ADM4073T 0.2 0 -50
05131-012
0
5
10
15
20
25
30
0
50 TEMPERATURE (C)
100
150
COMMON-MODE VOLTAGE (V)
Figure 11. Total Output Error vs. Common-Mode Voltage
0.10 0.08 TOTAL OUTPUT ERROR (%) 0.06 0.04 0.02 0 VCC = 28V VCC = 12V 50 70
Figure 14. O/P High Voltage (VCC - VOH) vs. Temperature
ADM4073F 60
PSRR (dB)
40 30 20 10 0 0.1 ADM4073H ADM4073T
-0.02 -0.04 -0.06 -0.08
05131-013
0
50 TEMPERATURE (C)
100
150
1
10
100
1000
10000
FREQUENCY (kHz)
Figure 12. Total Output Error vs. Temperature
Figure 15. PSRR vs. Frequency
Rev. 0 | Page 7 of 12
05131-016
-0.10 -50
05131-015
05131-014
ADM4073
45 ADM4073H 40 35 30 ADM4073F
100mV
GAIN (dB)
ADM4073T
VSENSE 2.5mV/DIV
95mV
25 20
10V
15 10 5
05131-017
OUT 250mV/DIV
9.5V
05131-020
0 0.1
1
10
100
1000
10000
1s/DIV
FREQUENCY (kHz)
Figure 16. Small Signal Gain vs. Frequency
Figure 19. ADM4073H Small Signal Transient Response
100mV
100mV
VSENSE 2.5mV/DIV
95mV
VSENSE 45mV/DIV
6.25mV
2V
2V
OUT 50mV/DIV
1.9V
05131-018
OUT 0.9V/DIV
0.120V
05131-021
1s/DIV
1s/DIV
Figure 17. ADM4073T Small Signal Transient Response
Figure 20. ADM4073T Large Signal Transient Response
100mV
100mV
VSENSE 2.5mV/DIV
95mV
VSENSE 45mV/DIV
6.25mV
5V
5V
OUT 125mV/DIV
4.75V
05131-019
OUT 2.35V/DIV
0.3V
05131-022
1s/DIV
1s/DIV
Figure 18. ADM4073F Small Signal Transient Response
Figure 21. ADM4073F Large Signal Transient Response
Rev. 0 | Page 8 of 12
ADM4073
VCC = 0V TO 4V 100mV 4V
VSENSE 45mV/DIV
6.25mV
VCC 2V/DIV
0V
10V
2V
OUT 4.7V/DIV
0.6V
05131-023
OUT 1V/DIV
0V
05131-025
1s/DIV
1s/DIV
Figure 22. ADM4073H Large Signal Transient Response
Figure 24. ADM4073T Start-Up Delay
VCC = 3V 250mV
VSENSE 100mV/DIV
50mV
VOH
OUT 600mV/DIV
1V
05131-024
1s/DIV
Figure 23. ADM4073T Overdrive Response
Rev. 0 | Page 9 of 12
ADM4073 THEORY OF OPERATION
The current from the source flows through RSENSE, which generates a voltage drop, VSENSE, across the RS+ and RS- terminals of the sense amplifier. The Input Stage Amplifier A1 regulates its inputs to be equal, thereby shunting a current proportional to VSENSE/RG1 to the output current mirror. This current is then multiplied by a gain factor b in the output stage current mirror and flows through RGD to generate VOUT. Therefore, VOUT is related to VSENSE by the ratio of R G1 to RGD and the current gain b. VOUT = AV x VSENSE where: AV = RGD/R G1 x b where: AV = 20 V/V (for ADM4073T). AV = 50 V/V (for ADM4073H). AV = 100 V/V (for ADM4073F).
ILOAD 2V TO 28V RS+ IRG1 RG1 RG2 RSENSE RS- VOUT
To measure lower currents accurately, as large a sense resistor as possible should be used to utilize the higher end of the sense voltage range. This reduces the effects of the offset voltage errors in the internal amplifier. When currents are very large, it is important to take the I2R power losses across the sense resistor into account. If the sense resistor's rated power dissipation is not sufficient, its value can drift, giving an inaccurate output voltage, or it could fail altogether. This, in turn, causes the voltage across the RS+ and RS- pins to exceed the absolute maximum ratings. If the monitored supply rail has a large amplitude high frequency component, a sense resistor with low inductance should be chosen.
RSENSE INPUT COPPER PCB TRACE OUTPUT
RS+ 3V TO 28V 0.1F VCC
RS-
OUT
ADM4073
GND
0.1F
AV
Figure 26. Using PCB Trace for Current Sensing
OUTPUT (OUT)
ADM4073
CURRENT MIRROR IRGD GND RGD = 12k
05131-003
VOUT
The output stage of the ADM4073 is a current source driving a pull-down resistance. To ensure optimum accuracy, care must be taken not to load this output externally. To minimize output errors, ensure OUT is connected to a high impedance input stage. If this is not possible, output buffering is recommended. The percent error introduced by output loading is determined with the following formula:
Figure 25. Functional Block Diagram
RSENSE
The ADM4073 has the ability to sense a wide variety of currents by selecting a particular sense resistor. Select a suitable output voltage for full-scale current, for example, 10 V for 10 A. Then select a gain model that gives the most efficient use of the sense voltage range (150 mV max). In the example above, using the ADM4073H (gain of 100) give an output voltage of 10 V when the sense voltage is 100 mV. Use the following equation to determine what value of sense resistor gives 100 mV with 10 A flowing through it: RSENSE = 100 mV/10 A RSENSE = 10 m VOUT = (ILOAD x RSENSE) x AV
% Error = 100 ((RLOAD / ROUT _ INT + RSENSE ) - 1)
where: RLOAD is the external load applied to OUT. ROUT_INT is the internal output resistance (12 k).
Rev. 0 | Page 10 of 12
05131-004
3V TO 28V
VCC
ADM4073 OUTLINE DIMENSIONS
2.90 BSC
6 5 4
1.60 BSC
1 2 3
2.80 BSC
PIN 1 INDICATOR 0.95 BSC 1.30 1.15 0.90 1.90 BSC
1.45 MAX 0.50 0.30
0.22 0.08 10 4 0 0.60 0.45 0.30
0.15 MAX
SEATING PLANE
COMPLIANT TO JEDEC STANDARDS MO-178-AB
Figure 27. 6-Lead Small Outline Transistor Package [SOT-23] (RJ-6) Dimensions shown in millimeters
ORDERING GUIDE
Model ADM4073TWRJZ-REEL7 1 ADM4073FWRJZ-REEL71 ADM4073HWRJZ-REEL71
1
Gain 20 50 100
Temperature Range -40C to +125C -40C to +125C -40C to +125C
Package Description 6-Lead SOT-23 6-Lead SOT-23 6-Lead SOT-23
Package Option RJ-6 RJ-6 RJ-6
Branding M2E M2C M2D
Z = Pb-free part.
Rev. 0 | Page 11 of 12
ADM4073 NOTES
(c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05131-0-7/06(0)
Rev. 0 | Page 12 of 12

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