Low Cost, Voltage Output,
High-Side, Current-Sense Amplifier
ADM4073
Rev. A
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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 ©2006–2008 Analog Devices, Inc. All rights reserved.
FEATURES
Low cost, compact, current-sense solution
3 available gain versions
20 V/V (ADM4073T)
50 V/V (ADM4073F)
100 V/V (ADM4073H)
Typical ±1.0% full-scale accuracy
Supply current: 500 μA
Wide bandwidth: 1.8 MHz
Operating supply: 3 V to 28 V
Wide common-mode range: 2 V to 28 V
Independent of supply voltage
Operating temperature range: −40°C to +125°C
Available in a 6-lead SOT-23 package
Pin-to-pin compatibility with the MAX4073
APPLICATIONS
Cell phones
PDAs
Notebook computers
Portable, battery-powered systems
Smart battery packs and chargers
Automotive
Power management systems
PA bias control
General system-level, board-level current monitoring
Precision current sources
FUNCTIONAL BLOCK DIAGRAM
2V TO 28V
3V TO 28V
0.1µF
VOUT
RSENSE
ILOAD
IRG1
VOUT
RS+
GND
AV
RS–
VCC
RG2
RGD = 12kΩ
RG1
ADM4073
IRGD
CURRENT
MIRROR
05131-003
OUT
Figure 1.
APPLICATION DIAGRAM
2
V TO 28
V
3V TO 28V
0.1µF
V
OUT
R
SENSE
OUT
ADC
RS+
GND
RS–
V
CC
ADM4073
05131-001
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 μA.
The ADM4073 is available in a 6-lead SOT-23 package and is
specified over the automotive operating temperature range
(−40°C to +125°C).
ADM4073
Rev. A | Page 2 of 12
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
10/08—Rev. 0 to Rev. A
Changes to Theory of Operation Section and Output (OUT)
Section .............................................................................................. 10
Changes to Ordering Guide .......................................................... 11
7/06—Revision 0: Initial Version
ADM4073
Rev. A | Page 3 of 12
SPECIFICATIONS
VRS+ = 2 V to 28 V, VSENSE = (VRS+ − VRS−) = 0 V, VCC = 3 V to 28 V, TA = −40°C to +125°C, unless otherwise noted. Typical values are at TA = 25°C.1
Table 1.
Parameter Min Typ Max Unit Conditions
POWER SUPPLY
Operating Voltage Range, VCC 3 28 V Inferred from PSRR test
Common-Mode Input Range, VCMR 2 28 V Inferred OUT voltage error test
Common-Mode Input Rejection, CMR 90 dB VSENSE = 100 mV, VCC = 12 V
Supply Current, ICC 0.5 1.2 mA VCC = 28 V
Leakage Current, IRS+/IRS− 0.05 2 μA VCC = 0 V, VRS+ = 28 V, TA = 85°C
Input Bias Current, IRS+ 20 60 μA
Input Bias Current, IRS− 40 120 μA
Full-Scale Sense Voltage, VSENSE 150 mV VSENSE = (VRS+ − VRS−)
Total Output Voltage Error2
±1 % VSENSE = 100 mV, VCC = 12 V, VRS+ = 2 V
±1.0 ±5.0 % VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, TA = +25°C
±5.0 % VSENSE = 100 mV, VCC = 12 V, VRS = 12V, TA = −40°C to +125°C
±1.0 ±5.0 % VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = +25°C
±5.0 % VSENSE = 100 mV, VCC = 28 V, VRS = 28 V, TA = −40°C to +125°C
±7.5 % VSENSE = 6.25 mV,3 VCC = 12 V, VRS = 12 V
Extrapolated Input Offset Voltage, VOS 1.0 mV VCC = VRS+ = 12 V, VSENSE > 10 mV
Output High Voltage (VCC − VOH) 0.8 1.2 V VCC = 3 V, VSENSE = 150 mV (ADM4073T)
0.8 1.2 V VCC = 7.5 V, VSENSE = 150 mV (ADM4073F)
0.8 1.2 V VCC = 15 V, VSENSE = 150 mV (ADM4073H), TA = 25°C
DYNAMIC CHARACTERISTICS
Bandwidth, BW 1.8 MHz VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T)
1.7 MHz VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073F)
1.6 MHz VSENSE = 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073H)
600 kHz VSENSE = 6.25 mV,3 VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF (ADM4073T/F/H)
Gain, AV 20 V/V ADM4073T
50 V/V ADM4073F
100 V/V ADM4073H
Gain Accuracy ±1.0 ±2.0 % VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V,
TA = +25°C (ADM4073T/F)
±2.0 %
VSENSE = 10 mV to 150 mV, VCC = 12 V, VRS+ = 12 V,
TA = −40°C to +125°C (ADM4073T/F)
±1.0 ±1.5 %
VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V,
TA = +25°C (ADM4073H)
±3.0 %
VSENSE = 10 mV to 100 mV, VCC = 12 V, VRS+ = 12 V,
TA = −40°C to +125°C (ADM4073H)
OUT Settling Time to 1% of Final Value 400 ns VSENSE = 6.25 mV to 100 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF
800 ns VSENSE = 100 mV to 6.25 mV, VCC = 12 V, VRS+ = 12 V, CLOAD = 5 pF
Output Resistance, ROUT 12 kΩ
Power Supply Rejection Ratio, PSRR 78 dB VSENSE = 60 mV, VCC = 3 V to 28 V (ADM4073T)
85 dB VSENSE = 24 mV, VCC = 3 V to 28 V (ADM4073F)
90 dB VSENSE = 12 mV, VCC = 3 V to 28 V (ADM4073H)
Power-Up Time4
5 μs CLOAD = 5 pF, VSENSE = 100 mV
Saturation Recovery Time5
5 μs CLOAD = 5 pF, VCC = 12 V, VRS+ = 12 V
1 100% production tested at TA = 25°C. Specifications over temperature limit are guaranteed by design.
2 The sum of the gain and offset errors is the total OUT voltage error.
3 6.25 mV = 1/16th of 100 mV full-scale sense voltage.
4 Output settles to within 1% of final value.
5 When overdriven, this device does not experience phase reversal.
ADM4073
Rev. A | Page 4 of 12
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
VCC to GND −0.3 V to +30 V
RS+, RS− to GND −0.3 V to +30 V
OUT to GND −0.3 V to (VCC + 0.3 V)
OUT Short-Circuit to GND Continuous
Differential Input Voltage (VRS+ − VRS−) ±5 V
Current into Any Pin ±20 mA
Storage Temperature Range −65°C to +125°C
Operating Temperature Range −40°C to +125°C
Lead Temperature, Soldering (10 sec) 300°C
Junction Temperature 150°C
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
θJA 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 θJA Unit
6-Lead SOT-23 169.5 °C/W
ESD CAUTION
ADM4073
Rev. A | Page 5 of 12
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
G
ND
1
G
ND
2
V
CC 3
OUT
6
RS–
5
RS+
4
TOP VIEW
(Not to Scale)
05131-002
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 GND Chip Ground Pin.
2 GND Chip Ground Pin.
3 VCC Chip Power Supply. Requires a 0.1 μF capacitor to ground.
4 RS+ Power-Side Connection to the External Sense Resistor.
5 RS− Load-Side Connection to the External Sense Resistor.
6 OUT Voltage Output. VOUT is proportional to VSENSE. Output impedance is approximately 12 kΩ.
ADM4073
Rev. A | Page 6 of 12
TYPICAL PERFORMANCE CHARACTERISTICS
0.60
0.30
030
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5 10152025
ADM4073H
ADM4073T
ADM4073F
V
SENSE
= 6.25mV
0.55
0.50
0.45
0.40
0.35
05131-005
Figure 4. Supply Current vs. Supply Voltage (VSENSE = 6.25 mV)
1.5
0.5
030
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5 10152025
ADM4073H
ADM4073T
ADM4073F
V
SENSE
= 100mV
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
05131-006
Figure 5. Supply Current vs. Supply Voltage (VSENSE = 100 mV)
0.7
0
–50 150
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
0.6
0.5
0.4
0.3
0.2
0.1
V
SENSE
= 0mV
V
CC
= 28V
–25 0 25 50 75 100 125
05131-007
Figure 6. Supply Current vs. Temperature
0.45
0.35
03
V
RS+
(V)
SUPPLY CURRENT (mA)
0
5 10152025
ADM4073H
ADM4073T
ADM4073F
0.43
0.41
0.39
0.37
V
SENSE
= 6.25mV
05131-008
Figure 7. Supply Current vs. RS+ Voltage (VSENSE = 6.25 mV)
1.5
0.5
03
V
RS+
(V)
SUPPLY CURRENT (mA)
0
5 10152025
ADM4073H
ADM4073T
ADM4073F
1.3
1.1
0.9
0.7
V
SENSE
= 100mV
05131-009
Figure 8. Supply Current vs. RS+ Voltage (VSENSE = 100 mV)
1.0
–1.0
03
SUPPLY VOLTAGE (V)
TOTAL OUTPUT ERROR (%)
0
5 10152025
ADM4073H
ADM4073T
ADM4073F
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
V
SENSE
= 100mV
05131-010
Figure 9. Total Output Error vs. Supply Voltage (VSENSE = 100 mV)
ADM4073
Rev. A | Page 7 of 12
1.0
–1.0
030
SUPPLY VOLTAGE (V)
TOTAL OUTPUT ERROR (%)
V
SENSE
= 6.25mV
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
ADM4073F
ADM4073T
ADM4073H
05131-011
5 10152025
Figure 10. Total Output Error vs. Supply Voltage (VSENSE = 6.25 mV)
1.0
–3.0
030
COMMON-MODE VOLTAGE (V)
TOTAL OUTPUT ERROR (%)
ADM4073H
5 10152025
ADM4073T
ADM4073F
–1.0
0.5
0
–0.5
–1.5
–2.0
–2.5
05131-012
Figure 11. Total Output Error vs. Common-Mode Voltage
0.10
–0.10
–50 150
TEMPERATURE (°C)
TOTAL OUTPUT ERROR (%)
0.08
0.06
0.04
0.02
0
–0.02
–0.04
–0.06
–0.08
V
CC
= 28V
V
CC
= 12V
0 50 100
05131-013
Figure 12. Total Output Error vs. Temperature
2.0
–2.0
–50 150
TEMPERATURE (°C)
GAIN ACCURACY (%)
0 50 100
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–25 25 75 125
05131-014
Figure 13. Gain Accuracy vs. Temperature
1.4
0
–50 150
TEMPERATURE (°C)
V
CC
– V
OH
(V)
05131-015
1.2
1.0
0.8
0.6
0.4
0.2
0 50 100
ADM4073T
ADM4073F
ADM4073H
Figure 14. Output High Voltage (VCC − VOH) vs. Temperature
70
0
0.1 10000
FREQUENCY (kHz)
PSRR (dB)
05131-016
60
50
40
30
20
10
1 10 100 1000
ADM4073F
ADM4073T
ADM4073H
Figure 15. PSRR vs. Frequency
ADM4073
Rev. A | Page 8 of 12
45
0
0.1 10000
FREQUENCY (kHz)
GAIN (dB)
05131-017
1 10 100 1000
ADM4073F
ADM4073T
ADM4073H
40
35
30
25
20
15
10
5
Figure 16. Small Signal Gain vs. Frequency
05131-018
1µs/DIV
100mV
95mV
2V
1.9V
V
SENSE
2.5mV/DI
V
OUT
50mV/DIV
Figure 17. ADM4073T Small Signal Transient Response
05131-019
1µs/DIV
100mV
95mV
5V
4.75V
V
SENSE
2.5mV/DIV
OUT
125mV/DI
V
Figure 18. ADM4073F Small Signal Transient Response
05131-020
1µs/DIV
100mV
95mV
10V
9.5V
V
SENSE
2.5mV/DIV
OUT
2
50mV/DI
V
Figure 19. ADM4073H Small Signal Transient Response
05131-021
1µs/DIV
100mV
6.25mV
2V
0.120V
V
SENSE
45mV/DIV
OUT
0.9V/DIV
Figure 20. ADM4073T Large Signal Transient Response
05131-022
1µs/DIV
100mV
6.25mV
5V
0.3V
V
SENSE
45mV/DIV
OUT
2.35V/DIV
Figure 21. ADM4073F Large Signal Transient Response
ADM4073
Rev. A | Page 9 of 12
05131-023
1µs/DIV
100mV
6.25mV
10V
0.6V
V
SENSE
45mV/DIV
OUT
4.7V/DIV
Figure 22. ADM4073H Large Signal Transient Response
05131-024
1µs/DIV
250mV
50mV
V
OH
1V
V
SENSE
100mV/DI
V
OUT
6
00mV/DI
V
V
CC
= 3V
Figure 23. ADM4073T Overdrive Response
05131-025
1µs/DIV
4V
0V
2V
0V
V
CC
2
V/DI
V
OUT
1V/DI
V
V
CC
= 0V TO 4V
Figure 24. ADM4073T Start-Up Delay
ADM4073
Rev. A | Page 10 of 12
THEORY OF OPERATION
The current from the source flows through RSENSE, which gen-
erates 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 of b in the output stage current mir-
ror 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
of b.
VOUT = AV × VSENSE
where:
AV = RGD/R G1 × b
Av is equal to different voltages depending upon the model of
the device.
• 20 V/V for ADM4073T.
• 50 V/V for ADM4073F.
• 100 V/V for ADM4073H.
2V TO 28V
3V TO 28V
0.1µF
V
OUT
R
SENSE
I
LOAD
I
RG1
V
OUT
RS+
GND
AV
RS–
V
CC
R
G2
R
GD
= 12kΩ
R
G1
ADM4073
I
RGD
CURRENT
MIRROR
05131-026
OUT
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, such as 10 V for 10 A. Then, select
a gain model that gives the most efficient use of the sense volt-
age range (150 mV max).
In the example above, using the ADM4073H (gain of 100) gives
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 mΩ
To measure lower currents accurately, use as large a sense
resistor as possible 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 alto-
gether. 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, choose a sense resistor with low
inductance.
INPUT COPPER PCB TRACE OUTPUT
3V TO 28
V
0.1µF
R
SENSE
OUT
RS+
GND
RS–
V
CC
ADM4073
05131-004
Figure 26. Using PCB Trace for Current Sensing
OUTPUT (OUT)
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:
(
)
(
)
LOAD
INTOUT
LOAD RRRError +
−
=
_
/1100%
where:
RLOAD is the external load applied to OUT.
ROUT_INT is the internal output resistance (12 kΩ).
VOUT = (ILOAD × RSENSE) × AV
ADM4073
Rev. A | Page 11 of 12
OUTLINE DIMENSIONS
1 3
45
2
6
2.90 BSC
1.60 BSC 2.80 BSC
1.90
BSC
0.95 BSC
0.22
0.08
10°
4°
0°
0.50
0.30
0.15 MAX
1.30
1.15
0.90
SEATING
PLANE
1.45 MAX
0.60
0.45
0.30
PIN 1
INDICATOR
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 Gain Temperature Range Package Description Package Option Branding
ADM4073TWRJZ-REEL71
20 −40°C to +125°C 6-Lead SOT-23 RJ-6 M2E
ADM4073FWRJZ-REEL71 50
−40°C to +125°C 6-Lead SOT-23 RJ-6 M2C
ADM4073HWRJZ-REEL71 100
−40°C to +125°C 6-Lead SOT-23 RJ-6 M2D
ADM4073WFWRJZ-RL71, 2
50 −40°C to +125°C 6-Lead SOT-23 RJ-6 M2C
1 Z = RoHS Compliant Part.
2 Automotive Grade.
ADM4073
Rev. A | Page 12 of 12
NOTES
©2006–2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05131-0-10/08(A)
