AD8207 [ADI]
Zero-Drift, High Voltage, Bidirectional Difference Amplifier; 零漂移，高压，双向差动放大器
| 型号： | AD8207 |
| 厂家： | 
ADI |
| 描述： | Zero-Drift, High Voltage, Bidirectional Difference Amplifier |
| 文件： | 总16页 (文件大小：430K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Zero-Drift, High Voltage,
Bidirectional Difference Amplifier
AD8207
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V+
Ideal for current shunt applications
EMI filters included
+IN
ZERO
OUT
1 μV/°C maximum input offset drift
High common-mode voltage range
−4 V to +65 V operating (5 V supply)
−4 V to +35 V operating (3.3 V supply)
−25 V to +75 V survival
DRIFT
–IN
AD8207
V
V
1
2
REF
Gain = 20 V/V
3.3 V to 5.5 V supply range
REF
RANGE
REF
Wide operating temperature range: −40°C to +125°C
Bidirectional current monitoring
<500 nV/°C typical offset drift
<10 ppm/°C typical gain drift
>90 dB CMRR dc to 10 kHz
GND
Figure 1.
Qualified for automotive applications
APPLICATIONS
High-side current sensing in
Motor control
Solenoid control
Engine management
Electric power steering
Suspension control
Vehicle dynamic control
DC-to-DC converters
GENERAL DESCRIPTION
The AD8207 is a single-supply difference amplifier ideal for
amplifying small differential voltages in the presence of large
common-mode voltage. The operating input common-mode
voltage range extends from −4 V to +65 V with a 5 V supply.
The AD8207 works with a single-supply voltage of 3.3 V to 5 V,
and is ideally suited to withstand large input PWM common-
mode voltages, typical in solenoid and motor control applications.
The AD8207 is ideal for bidirectional current sensing
applications. It features two reference pins,VREF1 and VREF2,
that allow the user to easily offset the output of the device to
any voltage within the supply range. With VREF1 attached to the
V+ pin and VREF2 attached to the GND pin, the output is set at
half scale. Attaching both pins to GND causes the output to
be unipolar, starting near ground. Attaching both pins to V+
causes the output to be unipolar starting near V+. Other output
offsets are achieved by applying an external low impedance
voltage to the VREF1 and VREF2 pins.
The AD8207 is available in an 8-lead SOIC package. Excellent
dc performance over temperature keeps errors in the mea-
surement loop to a minimum. Offset drift is typically less
than 500 nV/°C, and gain drift is typically below 10 ppm/°C.
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.
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One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
© 2010 Analog Devices, Inc. All rights reserved.
AD8207
TABLE OF CONTENTS
Features .............................................................................................. 1
Output Offset Adjustment ............................................................ 12
Unidirectional Operation.......................................................... 12
Bidirectional Operation............................................................. 12
External Referenced Output ..................................................... 13
Splitting the Supply .................................................................... 13
Splitting an External Reference ................................................ 13
Applications Information.............................................................. 14
Motor Control............................................................................. 14
Solenoid Control ........................................................................ 15
Outline Dimensions....................................................................... 16
Ordering Guide .......................................................................... 16
Automotive Products................................................................. 16
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
Power Supply Adjustment ............................................................. 11
3.3 V to 4.5 V Supply Operation .............................................. 11
4.5 V to 5.5 V Supply Operation .............................................. 11
REVISION HISTORY
7/10—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
AD8207
SPECIFICATIONS
TOPR = −40°C to +125°C, V+ = 5 V or 3.3 V, unless otherwise noted.
Table 1.
Parameter
Min
Typ
Max
Unit
Test Conditions/Comments
GAIN
Initial
20
V/V
%
Accuracy over Temperature
Gain vs. Temperature
VOLTAGE OFFSET
−0.3
−15
+0.3
0
TOPR
ppm/°C TOPR
Offset Voltage (RTI)1
Over Temperature (RTI)1
Offset Drift
±100
μV
μV
ꢀV/°C
25°C
TOPR
TOPR
±±00
+1
−1
INPUT
Input Impedance
Differential
Common Mode
Input Voltage Range
2±0
126
kΩ
kΩ
V
−±
−±
+65
+35
Common mode, continuous, V+ = 5 V, TOPR
Common mode continuous, V+ = 3.3 V, TOPR
Differential2, V+ = 5 V
V
250
90
mV
dB
Common-Mode Rejection (CMRR)
80
TOPR, f = dc to 20 kHz
OUTPUT
Output Voltage Range
Output Resistance
DYNAMIC RESPONSE
Small-Signal −3 dB Bandwidth
Slew Rate
0.02
V+ − 0.05
V
Ω
RL = 25 kΩ, TOPR
2
150
1
kHz
V/μs
TOPR
NOISE
0.1 Hz to 10 Hz, (RTI)1
Spectral Density, 1 kHz, (RTI)1
OFFSET ADJUSTMENT
Ratiometric Accuracy3
Accuracy (RTO)±
20
0.6
μV p-p
μV/√Hz
0.±97
0.503
±3
V/V
mV/V
Divider to supplies, TOPR
Voltage applied to VREF1 and VREF2 in parallel,
TOPR
Output Offset Adjustment Range
VREF Input Voltage Range5
VREF Divider Resistor Values
POWER SUPPLY
0.02
0.0
V+ − 0.05
V+
V
V
kΩ
TOPR
100
Operating Range
±.5
3.3
5.5
±.5
2.5
V
V
mA
dB
RANGE (Pin ±) connected to GND6
RANGE (Pin ±) connected to V+7
VO = 0.1 V dc
Quiescent Current over Temperature
Power Supply Rejection Ratio (PSRR)
TEMPERATURE RANGE
80
For Specified Performance
−±0
+125
°C
1 RTI = referred to input.
2 Input voltage range = ±125 mV with half-scale offset. The input differential range also depends on the supply voltage. The maximum input differential range can be
calculated by V+/20.
3 The offset adjustment is ratiometric to the power supply when VREF1 and VREF2 are used as a divider between the supplies.
± RTO = referred to output.
5 The reference pins should be driven with a low impedance voltage source to maintain the specified accuracy of the AD8207.
6 With a ±.5 V to 5.5 V supply, the RANGE pin should be tied low. In this mode, the common-mode range of the AD8207 is −± V to +65 V.
7 With a 3.3 V to ±.5 V supply, the RANGE pin should be tied to V+. In this mode, the common-mode range of the AD8207 is −± V to +35 V. If a ±.5 V supply is used, the
user can tie RANGE high or low depending on the common-mode range needed in the application.
Rev. 0 | Page 3 of 16
AD8207
ABSOLUTE MAXIMUM RATINGS
Table 2.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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.
Parameter
Rating
Supply Voltage
12.5 V
Continuous Input Voltage
Input Transient Survival
Differential Input Voltage
Reverse Supply Voltage
Operating Temperature Range
Storage Temperature Range
Output Short-Circuit Duration
−25 V to +75 V
−30 V to +80 V
−25 V to +75 V
0.3 V
−±0°C to +125°C
−65°C to +150°C
Indefinite
ESD CAUTION
Rev. 0 | Page ± of 16
AD8207
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
–IN
1
2
3
4
8
7
6
5
+IN
AD8207
GND
V
1
REF
V
2
V+
TOP VIEW
(Not to Scale)
REF
RANGE
OUT
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No.
Mnemonic
Description
1
2
3
±
5
6
7
8
−IN
GND
Negative Input.
Ground Pin.
Reference Input.
VREF
2
RANGE
OUT
V+
Range Pin. This pin switches between ±.5 V to 5.5 V and 3.3 V to ±.5 V supply operation.
Output.
Supply Pin.
Reference Input.
Positive Input.
VREF
1
+IN
Rev. 0 | Page 5 of 16
AD8207
TYPICAL PERFORMANCE CHARACTERISTICS
–10
40
30
–12
–14
–16
–18
–20
–22
–24
–26
–28
–30
20
10
0
–10
–20
–30
–40
–50
–60
–40
–20
0
20
40
60
80
100
120
140
1k
10k
100k
1M
10M
FREQUENCY (Hz)
TEMPERATURE (°C)
Figure 3. Typical Offset Drift vs. Temperature
Figure 6. Typical Small-Signal Bandwidth (VOUT = 200 mV p-p)
140
19
16
13
10
7
130
120
110
100
90
4
80
1
70
60
100
–2
1k
10k
100k
1M
0
5
10
15
20
25
30
35
40
45
50
FREQUENCY (Hz)
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 7. Total Output Error vs. Differential Input Voltage
Figure 4. Typical CMRR vs. Frequency
600
500
400
500
400
300
200
100
0
300
200
100
0
3.3V
–100
–200
–300
–400
–500
5V
–100
–200
–5
0
5
10 15 20 25 30 35 40 45 50 55 60 65
(V)
–40
–20
0
20
40
60
80
100
120
140
V
TEMPERATURE (°C)
CM
Figure 5. Typical Gain Error vs. Temperature
Figure 8. Input Bias Current vs. Common-Mode Voltage
Rev. 0 | Page 6 of 16
AD8207
2.0
1.8
1.6
1.4
1.2
1.0
100mV/DIV
1.0V/DIV
INPUT
5V
1
3.3V
OUTPUT
V+ = 3.3V
2
–5
5
15
25
35
45
55
65
TIME (1µs/DIV)
INPUT COMMON-MODE VOLTAGE (V)
Figure 9. Supply Current vs. Input Common-Mode Voltage
Figure 12. Fall Time (V+ = 3.3 V)
100mV/DIV
INPUT
INPUT
100mV/DIV
1
1
OUTPUT
2.0V/DIV
OUTPUT
V+ = 5V
V+ = 3.3V
1.0V/DIV
2
2
TIME (1µs/DIV)
TIME (1µs/DIV)
Figure 10. Rise Time (V+ = 3.3 V)
Figure 13. Fall Time (V+ = 5 V)
INPUT
INPUT
200mV/DIV
100mV/DIV
1
1
OUTPUT
V+ = 5V
OUTPUT
V+ = 3.3V
2.0V/DIV
2.0V/DIV
2
2
TIME (1µs/DIV)
TIME (10µs/DIV)
Figure 11. Rise Time (V+ = 5 V)
Figure 14. Differential Overload Recovery, Rising (V+ = 3.3 V)
Rev. 0 | Page 7 of 16
AD8207
INPUT
200mV/DIV
INPUT COMMON MODE
50V/DIV
1
OUTPUT
50mV/DIV
OUTPUT
2.0V/DIV
V+ = 5V
2
TIME (10µs/DIV)
TIME (2µs/DIV)
Figure 15. Differential Overload Recovery, Rising (V+ = 5 V)
Figure 18. Input Common-Mode Step Response (V+ = 5 V, Inputs Shorted)
7.0
6.5
6.0
5.5
200mV/DIV
INPUT
5.0
1
5V
4.5
3.3V
4.0
3.5
3.0
2.5
2.0
OUTPUT
2.0V/DIV
V+ = 3.3V
2
–40
–20
0
20
40
60
80
100
120
140
TIME (10µs/DIV)
TEMPERATURE (°C)
Figure 19. Maximum Output Sink Current vs. Temperature
Figure 16. Differential Overload Recovery, Falling (V+ = 3.3 V)
10
9
8
7
6
5
4
3
2
200mV/DIV
INPUT
5V
1
3.3V
OUTPUT
2.0V/DIV
V+ = 5V
2
1
–40
–20
0
20
40
60
80
100
120
140
TIME (10µs/DIV)
TEMPERATURE (°C)
Figure 20. Maximum Output Source Current vs. Temperature
Figure 17. Differential Overload Recovery, Falling (V+ = 5 V)
Rev. 0 | Page 8 of 16
AD8207
0
–100
–200
–300
–400
–500
–600
600
500
400
300
200
100
0
–40°C
+25°C
+125°C
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
–400 –300
–200 –100
0
100
200
300
400
OUTPUT SOURCE CURRENT (mA)
OFFSET (µV)
Figure 21. Output Voltage Range vs. Output Source Current
Figure 23. Input Offset Distribution
1000
800
600
400
200
0
1000
800
600
400
200
0
–14
–12
–10
–8
–6
–4
–2
0
0
1
2
3
4
5
6
7
8
OUTPUT SINK CURRENT (mA)
GAIN DRIFT (ppm/°C)
Figure 22. Output Voltage Range from GND vs. Output Sink Current
Figure 24. Gain Drift Distribution
Rev. 0 | Page 9 of 16
AD8207
THEORY OF OPERATION
The AD8207 is a single-supply, zero drift, difference amplifier
that uses a unique architecture to accurately amplify small
differential current shunt voltages in the presence of rapidly
changing common-mode voltage.
The reference inputs, VREF1 and VREF2, are tied through 100 kΩ
resistors to the positive input of the main amplifier, which
allows the output offset to be adjusted anywhere in the output
operating range. The gain is 1 V/V from the reference pins to
the output when the reference pins are used in parallel. When
the pins are used to divide the supply, the gain is 0.5 V/V.
In typical applications, the AD8207 is used to measure current
by amplifying the voltage across a shunt resistor connected to
its inputs.
The AD8207 offers breakthrough performance without
compromising any of the robust application needs typical
of solenoid or motor control. The part rejects PWM input
common-mode voltages, while the zero-drift architecture yields
the lowest offset and offset drift performance on the market.
SHUNT
The AD8207 includes a zero-drift amplifier, a precision resistor
network, a common-mode control amplifier, and a precision
reference (see Figure 25).
A set of precision-trimmed resistors make up the network
that attenuates the input common-mode voltage to within the
supply range of the amplifier, in this case with a ratio of 20/1.
This attenuation ensures that when the input pins are externally
at the common-mode extremes of −4 V and +65 V, the actual
voltage at the inputs of the main amplifier is still within the
supply range.
+IN
–IN
ZERO-DRIFT
AMPLIFIER
120kΩ
120kΩ
100kΩ
100kΩ
OUT
9kΩ
60kΩ 60kΩ
The input resistor network also attenuates normal (differential)
mode voltages. Therefore, the total internal gain of the AD8207
is set to 400 V/V to provide a total system gain of 20 V/V.
100kΩ
6kΩ
6kΩ
50kΩ
V
V
1
2
REF
REF
100kΩ
100kΩ
COMMON-MODE
CONTROL AMPLIFIER
Total Gain (V/V) = 1/20 (V/V) × 400 (V/V) = 20 V/V
The AD8207 is designed to provide excellent common-mode
rejection, even with PWM common-mode inputs that can
change at very fast rates, for example, 1 V/ns. An internal
common-mode control amplifier is used to maintain the input
common mode of the main amplifier at 3.5 V (with 5 V supply),
and therefore eliminates the negative effects of such fast-
changing external common-mode variations.
3.5V/2.2V
REF
AD8207
GND
Figure 25. Simplified Schematic
The AD8207 features an input offset drift of less than
500 nV/°C. This performance is achieved through a novel
zero-drift architecture that does not compromise band-
width, which is typically rated at 150 kHz.
Rev. 0 | Page 10 of 16
AD8207
POWER SUPPLY ADJUSTMENT
3.3 V TO 4.5 V SUPPLY OPERATION
4.5 V TO 5.5 V SUPPLY OPERATION
The AD8207 can operate with a single-supply voltage as low
as 3.3 V to 4.5 V. This mode of operation is achieved by con-
necting the RANGE pin (Pin 4) to the supply (see Figure 26).
It is recommended that an external resistor be placed in series
from the RANGE pin to the supply. This resistor can be a
typical 5 kΩ 1% resistor.
In most applications, the AD8207 operates with a single 5 V
supply. In this mode, the operating input common-mode
range of the AD8207 is rated from −4 V to +65 V. To operate
the device with a 5 V supply (includes 4.5 V to 5.5 V), connect
the RANGE pin (Pin 4) to logic low, or GND, as shown in
Figure 27.
SHUNT
SHUNT
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
AD8207
AD8207
3.3V
5V
TOP VIEW
(Not to Scale)
TOP VIEW
(Not to Scale)
3.3V
OUT
OUT
Figure 26. 3.3 V Supply Operation
Figure 27. 5 V Supply Bidirectional Operation
Note that in this mode of operation, the common-mode range
of the AD8207 is limited to −4 V to +35 V. The output and
reference input ranges are limited to the supply of the part. The
user can have a 4.5 V supply and connect the RANGE pin from
3.3 V to 4.5 V. Alternatively, the user can connect the RANGE
pin as high as 4.5 V, with the supply from 3.3 V to 4.5 V.
The output and reference input ranges are limited to the
supply voltage used. With a supply voltage from 4.5 V to 5.5 V,
the RANGE pin (Pin 4) should be connected to GND to achieve
the maximum input common-mode range specification of −4 V
to +65 V.
Rev. 0 | Page 11 of 16
AD8207
OUTPUT OFFSET ADJUSTMENT
The output of the AD8207 can be adjusted for unidirectional or
bidirectional operation.
V+ Referenced Output Mode
The V+ referenced output mode is set when both reference pins
are tied to the positive supply. This mode is typically used when
the diagnostic scheme requires detection of the amplifier and
the wiring before power is applied to the load (see Figure 29).
5V
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8207 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.
V+
For 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 for a
5 V supply or 165 mV for a 3.3 V supply. The required polarity
of the differential input depends on the output voltage setting.
If the output is set at the positive rail, the input polarity must
be negative to move the output down. If the output is set at
ground, the polarity must be positive to move the output up.
+IN
OUT
ZERO
DRIFT
–IN
AD8207
V
V
1
2
REF
RANGE
REF
REF
Ground Referenced Output Mode
GND
When using the AD8207 in the ground referenced output mode,
both reference inputs are tied to ground, which causes the output to
Figure 29. V+ Referenced Output Mode, V+ = 5 V
sit at the negative rail when there are 0 differential volts at the input
(see Figure 28).
Table 5. V+ Referenced Output
VIN (Referred to −IN)
V+ = 5 V
0 V
VO
5V
±.95 V
0.02 V
V+
−250 mV
V+ = 3.3 V
0 V
+IN
OUT
ZERO
DRIFT
–IN
3.25 V
0.02 V
−165 mV
AD8207
BIDIRECTIONAL OPERATION
V
V
1
2
REF
Bidirectional operation allows the AD8207 to measure currents
through a resistive shunt in two directions. In this case, the
output is set anywhere within the output range. Typically, it
is set at half scale for equal range in both directions. In some
cases, however, it is set at a voltage other than half scale when
the bidirectional current is asymmetrical.
RANGE
REF
REF
GND
Figure 28. Ground Referenced Output Mode, V+ = 5 V
Table 6. VO = (V+/2) with VIN = 0 V
Table 4. Ground Referenced Output
VIN (Referred to −IN)
VO
V+ = 5 V
VIN (Referred to −IN)
VO
+100 mV
−100 mV
V+ = 3.3 V
+67.5 mV
−67.5 mV
±.5 V
0.5 V
V+ = 5 V
0 V
250 mV
V+ = 3.3 V
0 V
0.02 V
±.95 V
3 V
0.3 V
0.02 V
3.25 V
165 mV
Adjusting the output is accomplished by applying voltages
to the reference inputs. VREF1 and VREF2 are tied to internal
resistors that connect to an internal offset node. There is no
operational difference between the pins.
Rev. 0 | Page 12 of 16
AD8207
5V
EXTERNAL REFERENCED OUTPUT
Tying both reference pins together and to an external reference
produces an output equal to the reference voltage when there is
no differential input (see Figure 30). The output moves down
from the reference voltage when the input is negative, relative
to the −IN pin, and up when the input is positive, relative to the
−IN pin. The reference pins are connected to the positive input
of the main amplifier via precision-trimmed 100 kΩ resistors.
Therefore, it is recommended that a low impedance voltage is
always be used to set the reference voltage. If external resistors
are connected directly to the VREF1 and VREF2 pins, there will
be a mismatch with the internal trimmed resistors, leading to
offset gain accuracy reduction.
V+
+IN
–IN
ZERO
DRIFT
OUT
AD8207
V
1
2
REF
REF
RANGE
REF
V
GND
5V
Figure 31. Splitting the Supply, V+ = 5 V
V+
SPLITTING AN EXTERNAL REFERENCE
+IN
ZERO
OUT
–IN
DRIFT
In Figure 32, an external reference is divided by 2 with an
accuracy of approximately 0.5% by connecting one VREF pin to
ground and the other VREF pin to the reference (see Figure 32).
5V
AD8207
V
1
REF
RANGE
VOLTAGE
REFERENCE
V+
2.5V
REF
+IN
V
2
ZERO
OUT
REF
DRIFT
–IN
GND
AD8207
Figure 30. External Referenced Output, V+ = 5 V
V
V
1
2
REF
REF
VOLTAGE
REFERENCE
5V
SPLITTING THE SUPPLY
RANGE
REF
By tying one reference pin to V+ and the other to the ground
pin, the output is set at half of the supply when there is no dif-
ferential input (see Figure 31). The benefit is that no external
reference is required to offset the output for bidirectional current
measurement. This creates a midscale offset that is ratiometric to
the supply, which means that if the supply increases or decreases,
the output remains at half the supply. 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 goes to 2.75 V.
GND
Figure 32. Splitting an External Reference, V+ = 5 V
Rev. 0 | Page 13 of 16
AD8207
APPLICATIONS INFORMATION
MOTOR CONTROL
3-Phase Motor Control
directions by using the shunt available at the motor. This is
a better solution than a ground referenced op amp because
ground is not typically a stable reference voltage in this type
of application. The instability of the ground reference causes
inaccuracies in the measurements that could be made with a
simple ground referenced op amp. The AD8207 measures
current in both directions as the H-bridge switches and the
motor changes direction. The output of the AD8207 is config-
ured in an external referenced bidirectional mode (see the
Bidirectional Operation section).
The AD8207 is ideally suited for monitoring current in 3-phase
motor applications.
The 150 kHz typical bandwidth of the AD8207 allows for
instantaneous current monitoring. Additionally, the typical
low offset drift of 500 nV/°C means that the measurement
error between the two motor phases will be at a minimum
over temperature. The AD8207 rejects PWM input common-
mode voltages in the range of −4 V to +65 V (with a 5 V
supply). Monitoring the current on the motor phase allows
for sampling of the current at any point and allows for
diagnostic information such as a short to GND and battery.
Refer to Figure 34 for a typical phase current measurement
setup with the AD8207.
CONTROLLER
5V
+IN
+V
OUT
V
1
S
REF
MOTOR
AD8207
5V
SHUNT
–IN GND
V
2 RANGE
REF
H-Bridge Motor Control
2.5V
Another typical application for the AD8207 is as part of
the control loop in H-bridge motor control. In this case, the
shunt resistor is placed in the middle of the H-bridge (see
Figure 33) so that it can accurately measure current in both
Figure 33. H-Bridge Motor Control Application
V+
M
I
I
I
U
V
W
V–
5V
5V
INTERFACE
AD8214
CIRCUIT
AD8207
AD8207
OPTIONAL
PART FOR
OVERCURRENT
PROTECTION AND
FAST (DIRECT)
SHUTDOWN OF
POWER STAGE
CONTROLLER
BIDIRECTIONAL CURRENT MEASUREMENT
REJECTION OF HIGH PWM COMMON-MODE VOLTAGE (–4V TO +65V)
AMPLIFICATION
HIGH OUTPUT DRIVE
Figure 34. 3-Phase Motor Control
Rev. 0 | Page 1± of 16
AD8207
High-Side Current Sense with a High-Side Switch
SOLENOID CONTROL
This configuration minimizes the possibility of unexpected
solenoid activation and excessive corrosion (see Figure 36). In
Figure 36, 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 shorts to ground, while
still allowing the recirculation current to be measured and
providing for diagnostics. Removing the power supply from the
load for the majority of the time minimizes the corrosive effects
that can be caused by the differential voltage between the load
and ground. When using a high-side switch, the battery voltage
is connected to the load when the switch is closed, causing the
common-mode voltage to increase to the battery voltage. 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.
High-Side Current Sense with a Low-Side Switch
Other typical applications for the AD8207 include current
monitoring for PWM control of solenoid openings. Typical
applications include hydraulic valve control, diesel injection
control, and actuator control.
In Figure 35, 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 35).
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 capabilities are enhanced
because shorts to ground can be detected with the shunt on
the high side. In this circuit configuration, when the switch
is closed, the common-mode voltage moves down to near 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.
5V
SWITCH
+IN
+V
OUT
V
1
S
REF
5V
SHUNT
AD8207
INDUCTIVE
LOAD
42V
BATTERY
–IN GND
V
2 RANGE
REF
CLAMP
DIODE
INDUCTIVE
LOAD
CLAMP
DIODE
+IN
V
1
+V
OUT
REF
S
SHUNT
42V
BATTERY
AD8207
–IN GND
V
2 RANGE
REF
Figure 36. High-Side Switch
SWITCH
Figure 35. Low-Side Switch
Rev. 0 | Page 15 of 16
AD8207
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
8
1
5
4
6.20 (0.2441)
5.80 (0.2284)
4.00 (0.1574)
3.80 (0.1497)
0.50 (0.0196)
0.25 (0.0099)
1.27 (0.0500)
BSC
45°
1.75 (0.0688)
1.35 (0.0532)
0.25 (0.0098)
0.10 (0.0040)
8°
0°
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
1.27 (0.0500)
0.40 (0.0157)
0.25 (0.0098)
0.17 (0.0067)
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MS-012-AA
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 37. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model1, 2
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
Package Option
AD8207WBRZ
AD8207WBRZ-R7
AD8207WBRZ-RL
8-Lead SOIC_N
8-Lead SOIC_N, 7”Tape and Reel
8-Lead SOIC_N, 13”Tape and Reel
R-8
R-8
R-8
1 Z = RoHS Compliant Part.
2 W = Qualified for Automotive Applications.
AUTOMOTIVE PRODUCTS
The AD8207 models are available with controlled manufacturing to support the quality and reliability requirements of automotive
applications. Note that these automotive models may have specifications that differ from the commercial models; therefore, designers
should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in
automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to
obtain the specific Automotive Reliability reports for these models.
©2010 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09160-0-7/10(0)
Rev. 0 | Page 16 of 16
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