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High Voltage, Bidirectional Current Shunt Monitor AD8210
FEATURES
4000 V HBM ESD High common-mode voltage range -2 V to +65 V operating -5 V to +68 V survival Buffered output voltage 5 mA output drive capability Wide operating temperature range: -40C to +125C Ratiometric half-scale output offset Excellent ac and dc performance 1 V/C typical offset drift 10 ppm/C typical gain drift 120 dB typical CMRR at dc 80 dB typical CMRR at 100 kHz Available in 8-lead SOIC
VSUPPLY
FUNCTIONAL BLOCK DIAGRAM
IS
RS +IN -IN V+ VS
AD8210
LOAD
VREF 1
G = +20
VOUT
APPLICATIONS
Current sensing Motor controls Transmission controls Diesel injection controls Engine management Suspension controls Vehicle dynamic controls DC-to-dc converters
GND
VREF 2
Figure 1.
GENERAL DESCRIPTION
The AD8210 is a single-supply, difference amplifier ideal for amplifying small differential voltages in the presence of large common-mode voltages. The operating input common-mode voltage range extends from -2 V to +65 V. The typical supply voltage is 5 V. The AD8210 is offered in a SOIC package. The operating temperature range is -40C to +125C. Excellent ac and dc performance over temperature keep errors in the measurement loop to a minimum. Offset drift and gain drift are guaranteed to a maximum of 8 V/C and 20 ppm/C, respectively. The output offset can be adjusted from 0.05 V to 4.9 V with a 5 V supply by using the VREF1 pin and the VREF2 pin. With the VREF1 pin attached to the V+ pin and the VREF2 pin attached to the GND pin, the output is set at half scale. Attaching both VREF1 and VREF2 to GND causes the output to be unipolar, starting near ground. Attaching both VREF1 and VREF2 to V+ causes the output to be unipolar, starting near V+. Other offsets can be obtained by applying an external voltage to VREF1 and VREF2.
Rev. A
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)2006-2007 Analog Devices, Inc. All rights reserved.
05147-001
AD8210 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 ESD Caution.................................................................................. 4 Pin Configuration and Function Descriptions............................. 5 Typical Performance Characteristics ............................................. 6 Theory of Operation ...................................................................... 10 Modes of Operation ....................................................................... 11 Unidirectional Operation.......................................................... 11 Bidirectional Operation............................................................. 11 Input Filtering ................................................................................. 13 Applications Information .............................................................. 14 High-Side Current Sense with a Low-Side Switch................. 14 High-Side Current Sense with a High-Side Switch ............... 14 H-Bridge Motor Control ........................................................... 14 Outline Dimensions ....................................................................... 15 Ordering Guide .......................................................................... 15
REVISION HISTORY
4/07--Rev. 0 to Rev. A Changes to Features.......................................................................... 1 Changes to Input Section................................................................. 3 Updated Outline Dimensions ....................................................... 15 4/06--Revision 0: Initial Version
Rev. A | Page 2 of 16
AD8210 SPECIFICATIONS
TA = operating temperature range, VS = 5 V, unless otherwise noted. Table 1.
Parameter GAIN Initial Accuracy Accuracy Over Temperature Gain Drift VOLTAGE OFFSET Offset Voltage (RTI) Over Temperature (RTI) Offset Drift INPUT Input Impedance Differential Common Mode Common-Mode Input Voltage Range Differential Input Voltage Range Common-Mode Rejection AD8210 SOIC 1 Min Typ Max 20 0.5 0.7 20 1.0 1.8 8.0 Unit V/V % % ppm/C mV mV V/C Conditions
25C, VO 0.1 V dc TA
25C TA
2 5 1.5 -2 100 80 80 250 120 95 80 +65
k M k V mV dB dB dB dB V kHz V/s V p-p nV/Hz
V common mode > 5 V V common mode < 5 V Common mode, continuous Differential 2 TA, f = dc, VCM > 5 V TA, f = dc to 100 kHz 3 , VCM < 5 V TA, f = 100 kHz3, VCM > 5 V TA, f = 40 kHz3, VCM > 5 V RL = 25 k
OUTPUT Output Voltage Range Output Impedance DYNAMIC RESPONSE Small Signal -3 dB Bandwidth Slew Rate NOISE 0.1 Hz to 10 Hz, RTI Spectral Density, 1 kHz, RTI OFFSET ADJUSTMENT Ratiometric Accuracy 4 Accuracy, RTO Output Offset Adjustment Range VREF Input Voltage Range VREF Divider Resistor Values POWER SUPPLY, VS Operating Range Quiescent Current Over Temperature Power Supply Rejection Ratio TEMPERATURE RANGE For Specified Performance
1 2 3
0.05 2 450 3 7 70 0.499 0.05 0.0 24 4.5 80 -40
4.9
32 5.0
0.501 0.6 4.9 VS 40 5.5 2
V/V mV/V V V k V mA dB C
Divider to supplies Voltage applied to VREF1 and VREF2 in parallel VS = 5 V
VCM > 5 V 5
+125
TMIN to TMAX = -40C to +125C. Differential input voltage range = 125 mV with half-scale output offset. Source imbalance < 2 . 4 The offset adjustment is ratiometric to the power supply when VREF1 and VREF2 are used as a divider between the supplies. 5 When the input common mode is less than 5 V, the supply current increases. This can be calculated with the following formula: IS = -0.7 (VCM) + 4.2 (see Figure 21).
Rev. A | Page 3 of 16
AD8210 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Supply Voltage Continuous Input Voltage (VCM) Reverse Supply Voltage ESD Rating HBM (Human Body Model) CDM (Charged Device Model) Operating Temperature Range Storage Temperature Range Output Short-Circuit Duration Rating 12.5 V -5 V to +68 V 0.3 V 4000 V 1000 V -40C to +125C -65C to +150C Indefinite
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.
ESD CAUTION
Rev. A | Page 4 of 16
AD8210 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
-IN 1 GND 2 VREF 2 3
8
8 7
+IN VREF 1
2
AD8210
7
NC = NO CONNECT
05147-003
6 V+ TOP VIEW NC 4 (Not to Scale) 5 OUT
6
Figure 2. Pin Configuration
05147-002
3
5
Table 3. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 Mnemonic -IN GND VREF2 NC OUT V+ VREF1 +IN X -443 -479 -466 +466 +501 +475 +443 Y +584 +428 -469 -537 -95 +477 +584
Figure 3. Metallization Diagram
Rev. A | Page 5 of 16
AD8210 TYPICAL PERFORMANCE CHARACTERISTICS
200 180 160 140 120 100 80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 -200 -40 2000 1600 1200
GAIN ERROR (ppm)
05147-030
800 400 0 -400 -800
VOSI (V)
-1200 -1600 -20 0 20 40 60 80 100 120 30 50 70 90 110 TEMPERATURE (C) -20 0 20 40 60 80 100 120 30 50 70 90 110 TEMPERATURE (C)
05147-033
05147-014
-30
-10
10
-2000 -40
-30
-10
10
Figure 4. Typical Offset Drift
140 130 120 110 100 90 -40C 80 70 60 100 30 25 20 15 10 5 0
Figure 7. Typical Gain Drift
CMRR (dB)
GAIN (dB)
100k
05147-032
+125C
+25C
-5 -10 -15 -20 -25 -30 -35 -40 -45 -50 10
1k
10k FREQUENCY (Hz)
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
Figure 5. CMRR vs. Frequency and Temperature (Common-Mode Voltage < 5 V)
140 130 +25C 120 110 100 90 80 70 60 100
Figure 8. Typical Small Signal Bandwidth (VOUT = 200 mV p-p)
100mV/DIV
500mV/DIV
-40C +125C
CMRR (dB)
1k
10k FREQUENCY (Hz)
100k
05147-031
400ns/DIV
Figure 6. CMRR vs. Frequency and Temperature (Common-Mode Voltage > 5 V)
Figure 9. Fall Time
Rev. A | Page 6 of 16
05147-017
AD8210
4V/DIV
100mV/DIV
0.02%/DIV
500mV/DIV
05147-018 05147-024 05147-019 05147-025
400ns/DIV
4s/DIV
Figure 10. Rise Time
Figure 13. Settling Time (Falling)
200mV/DIV
4V/DIV
0.02%/DIV
2V/DIV
1s/DIV
05147-016
4s/DIV
Figure 11. Differential Overload Recovery (Falling)
Figure 14. Settling Time (Rising)
50V/DIV
200mV/DIV
2V/DIV
05147-015
100mV/DIV
1s/DIV
1s/DIV
Figure 12. Differential Overload Recovery (Rising)
Figure 15. Common-Mode Response (Falling)
Rev. A | Page 7 of 16
AD8210
5.0 4.9 4.8
OUTPUT VOLTAGE RANGE (V)
05147-020
50V/DIV
4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5
100mV/DIV
1s/DIV
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 OUTPUT SOURCE CURRENT (mA)
Figure 16. Common-Mode Response (Rising)
8 7 6 5 4 3 2 1 0 -40
Figure 19. Output Voltage Range vs. Output Source Current
1.4
OUTPUT VOLTAGE RANGE FROM GND (V)
MAXIMUM OUTPUT SINK CURRENT (mA)
1.2 1.0 0.8 0.6 0.4 0.2 0
05147-022
-20
0
20
40
60
80
100
120
140
TEMPERATURE (C)
OUTPUT SINK CURRENT (mA)
Figure 17. Output Sink Current vs. Temperature
11
Figure 20. Output Voltage Range from GND vs. Output Sink Current
6.0 5.5 5.0
MAXIMUM OUTPUT SOURCE CURRENT (mA)
10 9
SUPPLY CURRENT (mA)
8 7 6 5 4 3 2 1
05147-026
4.5 4.0 3.5 3.0 2.5 2.0 1.5
-20
0
20
40
60
80
100
120
140
0
2
4
6
8
65
TEMPERATURE (C)
COMMON-MODE VOLTAGE (V)
Figure 18. Output Source Current vs. Temperature
Figure 21. Supply Current vs. Common-Mode Voltage
Rev. A | Page 8 of 16
05147-027
0 -40
1.0 -2
05147-038
0
1
2
3
4
5
6
7
8
9
05147-023
AD8210
2100 1800 1500
4000
+125C +25C -40C
3000
COUNT
COUNT
1200 900 600
2000
1000
300 0 -10 -9
05147-034
-6
-3
0
3
6
9 10
VOS DRIFT (V/C)
VOS (mV)
Figure 22. Offset Drift Distribution (V/C), SOIC, Temperature Range = -40C to +125C
3500 3000 2500
COUNT
Figure 24. Offset Distribution (V), SOIC, VCM = 5 V
4000 3500 3000 2500 2000 1500
+125C +25C -40C
2000 1500 1000 500 0
COUNT
1000 500 0 -2.0
GAIN DRIFT (ppm/C)
VOS (mV)
Figure 23. Gain Drift Distribution (ppm/C), SOIC, Temperature = -40C to +125C
Figure 25. Offset Distribution (V), SOIC, VCM = 0 V
Rev. A | Page 9 of 16
05147-037
0
3
6
9
12
15
18
20
05147-035
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
05147-036
0 -2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
AD8210 THEORY OF OPERATION
In typical applications, the AD8210 amplifies a small differential input voltage generated by the load current flowing through a shunt resistor. The AD8210 rejects high common-mode voltages (up to 65 V) and provides a ground referenced buffered output that interfaces with an analog-to-digital converter (ADC). Figure 26 shows a simplified schematic of the AD8210. The AD8210 is comprised of two main blocks, a differential amplifier and an instrumentation amplifier. A load current flowing through the external shunt resistor produces a voltage at the input terminals of the AD8210. The input terminals are connected to the differential amplifier (A1) by R1 and R2. A1 nulls the voltage appearing across its own input terminals by adjusting the current through R1 and R2 with Q1 and Q2. When the input signal to the AD8210 is 0 V, the currents in R1 and R2 are equal. When the differential signal is nonzero, the current increases through one of the resistors and decreases in the other. The current difference is proportional to the size and polarity of the input signal. The differential currents through Q1 and Q2 are converted into a differential voltage by R3 and R4. A2 is configured as an instrumentation amplifier. The differential voltage is converted into a single-ended output voltage by A2. The gain is internally set with precision-trimmed, thin film resistors to 20 V/V. The output reference voltage is easily adjusted by the VREF1 pin and the VREF2 pin. In a typical configuration, VREF1 is connected to VCC while VREF2 is connected to GND. In this case, the output is centered at VCC/2 when the input signal is 0 V.
ISHUNT
RSHUNT
R1
R2 VS
A1
AD8210
Q1
Q2
VREF 1 VOUT = (ISHUNT x RSHUNT ) x 20 A2
R3
R4
VREF 2
Figure 26. Simplified Schematic
Rev. A | Page 10 of 16
05147-004
GND
AD8210 MODES OF OPERATION
The AD8210 can be adjusted for unidirectional or bidirectional operation.
V+ Referenced Output
This mode is set when both reference pins are tied to the positive supply. It is typically used when the diagnostic scheme requires detection of the amplifier and wiring before power is applied to the load (see Figure 28 and Table 5).
RS +IN -IN
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8210 to measure currents through a resistive shunt in one direction. The basic modes for unidirectional operation are ground referenced output mode and V+ referenced output mode. In unidirectional operation, the output can be set at the negative rail (near ground) or at the positive rail (near V+) when the differential input is 0 V. The output moves to the opposite rail when a correct polarity differential input voltage is applied. In this case, full scale is approximately 250 mV. The required polarity of the differential input depends on the output voltage setting. If the output is set at ground, the polarity needs to be positive to move the output up (see Table 5). If the output is set at the positive rail, the input polarity needs to be negative to move the output down (see Table 6).
VS
AD8210
0.1F
VREF 1
OUTPUT G = +20
Ground Referenced Output
When using the AD8210 in this mode, both reference inputs are tied to ground, which causes the output to sit at the negative rail when the differential input voltage is zero (see Figure 27 and Table 4).
RS +IN -IN VREF 2
GND
05147-006
Figure 28. V+ Referenced Output
Table 5. V+ = 5 V
VS 0.1F
AD8210
VIN (Referred to -IN) 0V -250 mV
VO 4.9 V 0.05 V
BIDIRECTIONAL OPERATION
VREF 1
OUTPUT G = +20
VREF 2
Bidirectional operation allows the AD8210 to measure currents through a resistive shunt in two directions. The output offset can be set anywhere within the output range. Typically, it is set at half scale for equal measurement range in both directions. In some cases, however, it is set at a voltage other than half scale when the bidirectional current is nonsymmetrical. Table 6. V+ = 5 V, VO = 2.5 V with VIN = 0 V
GND
05147-005
VIN (Referred to -IN) +125 mV -125 mV
VO 4.9 V 0.05 V
Figure 27. Ground Referenced Output
Table 4. V+ = 5 V
VIN (Referred to -IN) 0V 250 mV VO 0.05 V 4.9 V
Adjusting the output can also be accomplished by applying voltage(s) to the reference inputs.
Rev. A | Page 11 of 16
AD8210
External Referenced Output
Tying both VREF pins together to an external reference produces an output offset at the reference voltage when there is no differential input (see Figure 29). When the input is negative relative to the -IN pin, the output moves down from the reference voltage. When the input is positive relative to the -IN pin, the output increases.
RS +IN -IN
G = +20 +IN RS -IN
VS
0.1F
AD8210
VREF 1
VREF 0V VREF VS
VS
0.1F
OUTPUT
AD8210
VREF 2
VREF VREF 1 0V VREF VS
GND
05147-008
OUTPUT G = +20
Figure 30. Split External Reference
Splitting the Supply
VREF 2
Figure 29. External Reference Output
Splitting an External Reference
In this case, an external reference is divided by two with an accuracy of approximately 0.2% by connecting one VREF pin to ground and the other VREF pin to the reference voltage (see Figure 30). Note that Pin VREF1 and Pin VREF2 are tied to internal precision resistors that connect to an internal offset node. There is no operational difference between the pins. For proper operation, the AD8210 output offset should not be set with a resistor voltage divider. Any additional external resistance could create a gain error. A low impedance voltage source should be used to set the output offset of the AD8210.
05147-007
GND
By tying one reference pin to V+ and the other to the GND pin, the output is set at midsupply when there is no differential input (see Figure 31). This mode is beneficial because no external reference is required to offset the output for bidirectional current measurement. This creates a midscale offset that is ratiometric to the supply, meaning that if the supply increases or decreases, the output still remains at half scale. For example, if the supply is 5.0 V, the output is at half scale or 2.5 V. If the supply increases by 10% (to 5.5 V), the output also increases by 10% (2.75 V).
RS +IN -IN
VS
AD8210
0.1F
VREF 1
G = +20
OUTPUT
VREF 2
GND
05147-009
Figure 31. Split Supply
Rev. A | Page 12 of 16
AD8210 INPUT FILTERING
In typical applications, such as motor and solenoid current sensing, filtering at the input of the AD8210 can be beneficial in reducing differential noise, as well as transients and current ripples flowing through the input shunt resistor. An input lowpass filter can be implemented as shown in Figure 32. The 3 dB frequency for this filter can be calculated by
f _ 3 dB = 1 2 x RFILTER x C FILTER
Adding outside components, such as RFILTER and CFILTER, introduces additional errors to the system. To minimize these errors as much as possible, it is recommended that RFILTER be 10 or lower. By adding the RFILTER in series with the 2 k internal input resistors of the AD8210, a gain error is introduced. This can be calculated by
(1)
2 k Gain Error (%) = 100 - 100 x 2 k - RFILTER
(2)
RSHUNT < RFILTER RFILTER 10 CFILTER RFILTER 10
+IN
-IN
VS
0.1F
AD8210
VREF VREF 1 0V VREF VS
G = +20
OUTPUT
VREF 2
GND
05147-013
Figure 32. Input Low-Pass Filtering
Rev. A | Page 13 of 16
AD8210 APPLICATIONS INFORMATION
The AD8210 is ideal for high-side or low-side current sensing. Its accuracy and performance benefits applications, such as 3-phase and H-bridge motor control, solenoid control, and power supply current monitoring. For solenoid control, two typical circuit configurations are used: high-side current sense with a low-side switch, and high-side current sense with a high-side switch.
BATTERY SHUNT CLAMP DIODE -IN 5V 0.1F SWITCH +IN VREF 1 +VS OUT
AD8210
GND VREF 2 NC
HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE SWITCH
In this case, the PWM control switch is ground referenced. An inductive load (solenoid) is tied to a power supply. A resistive shunt is placed between the switch and the load (see Figure 33). An advantage of placing the shunt on the high side is that the entire current, including the recirculation current, can be measured because the shunt remains in the loop when the switch is off. In addition, diagnostics can be enhanced because short circuits to ground can be detected with the shunt on the high side.
5V INDUCTIVE LOAD 0.1F
INDUCTIVE LOAD NC = NO CONNECT
05147-011
Figure 34. High-Side Switch
Using a high-side switch connects the battery voltage to the load when the switch is closed. This causes the common-mode voltage to increase to the battery voltage. In this case, when the switch is opened, the voltage reversal across the inductive load causes the common-mode voltage to be held one diode drop below ground by the clamp diode.
H-BRIDGE MOTOR CONTROL
Another typical application for the AD8210 is as part of the control loop in H-bridge motor control. In this case, the AD8210 is placed in the middle of the H-bridge (see Figure 35) so that it can accurately measure current in both directions by using the shunt available at the motor. This configuration is beneficial for measuring the recirculation current to further enhance the control loop diagnostics.
05147-010
CLAMP DIODE
BATTERY SHUNT
+IN
VREF 1
+VS
OUT
AD8210
-IN GND VREF 2 NC
SWITCH
5V 0.1F CONTROLLER
NC = NO CONNECT
Figure 33. Low-Side Switch
In this circuit configuration, when the switch is closed, the common-mode voltage moves down to the negative rail. When the switch is opened, the voltage reversal across the inductive load causes the common-mode voltage to be held one diode drop above the battery by the clamp diode.
MOTOR
+IN SHUNT -IN
VREF 1
+VS
OUT
AD8210
GND VREF 2 NC 5V
HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE SWITCH
This configuration minimizes the possibility of unexpected solenoid activation and excessive corrosion (see Figure 34). In this case, both the switch and the shunt are on the high side. When the switch is off, the battery is removed from the load, which prevents damage from potential short circuits to ground, while still allowing the recirculation current to be measured and diagnostics to be preformed. Removing the power supply from the load for the majority of the time minimizes the corrosive effects that could be caused by the differential voltage between the load and ground.
NC = NO CONNECT
Figure 35. Motor Control Application
The AD8210 measures current in both directions as the H-bridge switches and the motor changes direction. The output of the AD8210 is configured in an external reference bidirectional mode (see the Modes of Operation section).
Rev. A | Page 14 of 16
05147-012
2.5V
AD8210 OUTLINE DIMENSIONS
5.00 (0.1968) 4.80 (0.1890)
4.00 (0.1574) 3.80 (0.1497)
8 1
5 4
6.20 (0.2441) 5.80 (0.2284)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE
1.75 (0.0688) 1.35 (0.0532)
0.50 (0.0196) 0.25 (0.0099) 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157)
45
0.51 (0.0201) 0.31 (0.0122)
COMPLIANT TO JEDEC STANDARDS MS-012-A A CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 36. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model AD8210YRZ 1 AD8210YRZ-REEL1 AD8210YRZ-REEL71
1
Temperature Range -40C to +125C -40C to +125C -40C to +125C
Package Description 8-Lead SOIC_N 8-Lead SOIC_N, 13" Tape and Reel 8-Lead SOIC_N, 7" Tape and Reel
012407-A
Package Option R-8 R-8 R-8
Z = RoHS Compliant Part.
Rev. A | Page 15 of 16
AD8210 NOTES
(c)2006-2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05147-0-4/07(A)
T T
Rev. A | Page 16 of 16

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