AD8418AWBRZ-RL [ADI]
Bidirectional, Zero-Drift, Current Sense Amplifier;
| 型号： | AD8418AWBRZ-RL |
| 厂家： | 
ADI |
| 描述： | Bidirectional, Zero-Drift, Current Sense Amplifier 光电二极管 |
| 文件： | 总18页 (文件大小：452K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Bidirectional, Zero Drift,
Current Sense Amplifier
AD8418A
Data Sheet
FEATURES
GENERAL DESCRIPTION
Typical 0.1 μV/°C offset drift
The AD8418A is a high voltage, high resolution current shunt
amplifier. It features an initial gain of 20 V/V, with a maximum
0.15% gain error over the entire temperature range. The buffered
output voltage directly interfaces with any typical converter. The
AD8418A offers excellent input common-mode rejection from
−2 V to +70 V. e AD8418A performs bidirectional current
measurements across a shunt resistor in a variety of automotive
and industrial applications, including motor control, power
management, and solenoid control.
Maximum 200 μV voltage offset over full temperature range
2.7 V to 5.5 V power supply operating range
Electromagnetic interference (EMI) filters included
High common-mode input voltage range
−2 V to +70 V, continuous operation
−3 V to +80 V, continuous survival
Minimum DC common-mode rejection ratio (CMRR): 90 dB
Initial gain = 20 V/V
Wide operating temperature range
The AD8418A offers breakthrough performance throughout
the −40°C to +150°C temperature range. It features a zero drift
core, which leads to a typical offset drift of 0.1 μV/°C throughout
the operating temperature range and the common-mode voltage
range. The AD8418A is qualified for automotive applications.
The device includes EMI filters and patented circuitry to enable
output accuracy with pulse-width modulation (PWM) type
input common-mode voltages. The typical input offset voltage
is 100 μV. The AD8418A is offered in an 8-lead MSOP and an
8-lead SOIC_N package with a 10-lead MSOP pinout option
engineered for failure mode and effects analysis (FMEA).
AD8418AWB and AD8418AB: −40°C to +125°C
AD8418AWH: −40°C to +150°C
Bidirectional operation
Available in 8-lead SOIC_N, 8-lead MSOP, and FMEA tolerant
10-lead MSOP pinout
AEC-Q100 qualified for automotive applications
APPLICATIONS
High-side current sensing in
Motor controls
Solenoid controls
Power management
Low-side current sensing
Diagnostic protection
Table 1. Related Devices
Part No.
AD8205
AD8206
AD8207
AD8210
AD8417
Description
Current sense amplifier, gain = 50
Current sense amplifier, gain = 20
High accuracy current sense amplifier, gain = 20
High speed current sense amplifier, gain = 20
High accuracy current sense amplifier, gain = 60
FUNCTIONAL BLOCK DIAGRAM
V
= –2V TO +70V
V = 2.7V TO 5.5V
S
CM
70V
V
V
1
REF
S
V
OUT
V
V
S
AD8418A
CM
0V
+IN
–IN
EMI
+
–
FILTER
I
SHUNT
OUT
G = 20
R
SHUNT
V /2
S
EMI
FILTER
50A
SHUNT
–50A
I
0V
GND
V
2
REF
Figure 1.
Rev. E
Document Feedback
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 registeredtrademarks 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 ©2013–2020 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
AD8418A
Data Sheet
TABLE OF CONTENTS
Features.............................................................................................. 1
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
Pinout Option Engineered for FMEA..................................... 16
Outline Dimensions....................................................................... 17
Ordering Guide .......................................................................... 18
Automotive Products ................................................................ 18
Applications ...................................................................................... 1
General Description......................................................................... 1
Functional Block Diagram .............................................................. 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 ...................................................................... 11
Output Offset Adjustment ............................................................ 12
Unidirectional Operation.......................................................... 12
REVISION HISTORY
6/2020—Rev. D to Rev. E
4/2017—Rev. A to Rev. B
Changes to Features Section and
Changes to Features Section and General Description Section.......1
Changes to Table 2............................................................................3
Changes to Table 3............................................................................4
Change to Figure 18..........................................................................8
Added Figure 19 and Figure 20; Renumbered Sequentially........8
General Description Section........................................................... 1
Changes to Figure 2 Caption and Table 4 Title ........................... 6
Added Figure 3 and Table 5; Renumbered Sequentially ............ 6
Added Pinout Option Engineered for FMEA Section, Table 6,
and Table 7 ...................................................................................... 17
Updated Outline Dimensions....................................................... 19
Changes to Ordering Guide.......................................................... 19
12/2014—Rev. 0 to Rev. A
Added AD8418AWH ........................................................Universal
Changes to Features Section and General Description Section .......1
Changes to Specifications Section and Table 2.............................3
Changes to Table 3............................................................................4
Changes to Ordering Guide.......................................................... 16
12/2018—Rev. C to Rev. D
Changes to Features Section ........................................................... 1
Changes to Table 3 ........................................................................... 4
5/2018—Rev. B to Rev. C
11/2013—Revision 0: Initial Version
Changes to Input Bias Current Parameter, Table 2..................... 3
Changes to Figure 20 ....................................................................... 8
Rev. E | Page 2 of 18
Data Sheet
AD8418A
SPECIFICATIONS
TA = −40°C to +125°C (operating temperature range) for the AD8418AWB, TA = −40°C to +150°C for the AD8418AWH, VS = 5 V,
unless otherwise noted.
Table 2.
Parameter
Test Conditions/Comments
Min
−5
Typ
Max
Unit
GAIN
Initial
Error Over Temperature
Gain vs. Temperature
VOLTAGE OFFSET
20
V/V
%
ppm/°C
Specified temperature range
0.15
+5
Offset Voltage, Referred to the Input, RTI
Over Temperature, RTI
Offset Drift
25°C
100
μV
μV
μV/°C
Specified temperature range
200
+0.4
−0.4
+0.1
130
INPUT
Input Bias Current
μA
μA
+IN = −IN = 12 V, VREF1 = VREF2 = 2.5 V,
AD8418AWB
Common mode, continuous
Specified temperature range, f = dc
f = dc to 10 kHz
260
+70
Input Voltage Range
Common-Mode Rejection Ratio (CMRR)
−2
90
V
dB
dB
100
86
OUTPUT
Output Voltage Range
Output Resistance
Maximum Capacitive Load
DYNAMIC RESPONSE
RL = 25 kΩ
0.032
0
VS − 0.032
500
V
Ω
pF
2
No continuous oscillation
Small Signal −3 dB Bandwidth
Slew Rate
250
1
kHz
V/μs
NOISE
0.1 Hz to 10 Hz (RTI)
2.3
μV p-p
Spectral Density, 1 kHz, RTI
OFFSET ADJUSTMENT
Ratiometric Accuracy1
Accuracy, Referred to the Output (RTO)
Output Offset Adjustment Range
POWER SUPPLY
110
nV/√Hz
Divider to supplies
Voltage applied to VREF1 and VREF2 in parallel
VS = 5 V
0.4985
0.032
2.7
0.5015
1
VS − 0.032
V/V
mV/V
V
Operating Range
5.5
V
Quiescent Current Over Temperature
VOUT = 0.1 V dc
AD8418AWB and AD8418AB
AD8418AWH
4.1
4.2
mA
mA
dB
Power Supply Rejection Ratio
TEMPERATURE RANGE
80
For Specified Performance
Operating temperature range
AD8418AWB and AD8418AB
AD8418AWH
−40
−40
+125
+150
°C
°C
1 The offset adjustment is ratiometric to the power supply when VREF1 and VREF2 are used as a divider between the supplies.
Rev. E | Page 3 of 18
AD8418A
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 3.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
Parameter
Rating
Supply Voltage
Input Voltage Range
Common-Mode
6 V
−3 V to +80 V
5.5 V (magnitude)
0.3 V
Differential
Reverse Supply Voltage
ESD Human Body Model (HBM)
Operating Temperature Range
AD8418AWB and AD8418AB
AD8418AWH
Storage Temperature Range
Output Short-Circuit Duration
SOIC Package
2000 V
ESD CAUTION
−40°C to +125°C
−40°C to +150°C
−65°C to +150°C
Indefinite
θJA Thermal Resistance
MSOP Package
127.4°C/W
134.5°C/W
θJA Thermal Resistance
Rev. E | Page 4 of 18
Data Sheet
AD8418A
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
–IN
1
2
3
4
8
7
6
5
+IN
AD8418A
GND
V
V
1
REF
S
TOP VIEW
V
2
REF
(Not to Scale)
NC
OUT
NC = NO CONNECT. DO NOT
CONNECT TO THIS PIN.
Figure 2. 8-lead MSOP and 8-lead SOIC Pin Configuration
Table 4. 8-lead MSOP and 8-lead SOIC Pin Function Descriptions
Pin No.
Mnemonic
Description
1
2
3
4
5
6
7
8
−IN
GND
Negative Input.
Ground.
Reference Input 2.
No Connect. Do not connect to this pin.
Output.
Supply.
Reference Input 1.
Positive Input.
VREF
NC
2
OUT
VS
VREF
1
+IN
–IN
NC
1
2
3
4
5
10 +IN
9
8
7
6
NC
V
AD8418A
TOP VIEW
(Not to Scale)
GND
1
REF
V
2
V
S
REF
NC
OUT
NOTES
1. NC = NO CONNECT. DO NOT CONNECT TO THIS PIN.
Figure 3. 10-lead MSOP Pin Configuration
Table 5. 10-lead MSOP Pin Function Descriptions
Pin No.
Mnemonic
Description
1
−IN
NC
GND
Negative Input.
No Connect. Do not connect to this pin.
Ground.
2, 5, 9
3
4
6
7
VREF
OUT
VS
2
Reference Input 2.
Output.
Supply.
8
10
VREF
+IN
1
Reference Input 1.
Positive Input.
Rev. E | Page 5 of 18
AD8418A
Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS
100
40
30
90
80
70
60
50
40
30
20
10
0
20
10
0
–10
–20
–30
–40
–50
–60
1k
10k
100k
1M
10M
–
40 –25 –10
5
20
35
50
65
80
95 110 125
FREQUENCY (Hz)
TEMPERATURE (°C)
Figure 4. Typical Offset Drift vs. Temperature
Figure 7. Typical Small Signal Bandwidth (VOUT = 200 mV p-p)
110
20
18
16
14
12
10
8
100
90
80
70
60
50
6
4
2
0
–2
10
100
1k
10k
100k
1M
0
5
10
15
20
25
30
35
40
FREQUENCY (Hz)
DIFFERENTIAL INPUT VOLTAGE (mV)
Figure 5. Typical CMRR vs. Frequency
Figure 8. Total Output Error vs. Differential Input Voltage
400
300
0.5
0.4
NORMALIZED AT 25°C
V = 5V
S
0.3
200
0.2
+IN
100
0.1
–IN
0
0
–0.1
–0.2
–0.3
–0.4
–0.5
–100
–200
–300
–400
–4
0
4
8
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68
(V)
–40 –25 –10
5
20
35
50
65
80
95 110 125
V
TEMPERATURE (°C)
CM
Figure 9. Bias Current per Input Pin vs. Common-Mode Voltage (VCM
)
Figure 6. Typical Gain Error vs. Temperature
Rev. E | Page 6 of 18
Data Sheet
AD8418A
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
25mV/DIV
INPUT
V
= 5V
S
500mV/DIV
V
= 2.7V
S
OUTPUT
V
= 2.7V
S
–5
0
5
10 15 20 25 30 35 40 45 50 55 60 65 70
INPUT COMMON-MODE VOLTAGE (V)
TIME (1µs/DIV)
Figure 10. Supply Current vs. Input Common-Mode Voltage
Figure 13. Fall Time (VS = 2.7 V)
INPUT
50mV/DIV
INPUT
25mV/DIV
OUTPUT
1V/DIV
500mV/DIV
OUTPUT
V
= 2.7V
V
= 5V
S
S
TIME (1µs/DIV)
TIME (1µs/DIV)
Figure 11. Rise Time (VS = 2.7 V)
Figure 14. Fall Time (VS = 5 V)
INPUT
INPUT
100mV/DIV
50mV/DIV
OUTPUT
OUTPUT
1V/DIV
1V/DIV
V
= 5V
V
= 2.7V
S
S
TIME (1µs/DIV)
TIME (1µs/DIV)
Figure 12. Rise Time (VS = 5 V)
Figure 15. Differential Overload Recovery, Rising (VS = 2.7 V)
Rev. E | Page 7 of 18
AD8418A
Data Sheet
INPUT
200mV/DIV
500mV/DIV
OUTPUT
OUTPUT
2V/DIV
INPUT COMMON MODE
40V/DIV
V
= 5V
S
TIME (2µs/DIV)
TIME (1µs/DIV)
Figure 19. Input Common-Mode Step Response Large Scale
(VS = 5 V, Inputs Shorted)
Figure 16. Differential Overload Recovery, Rising (VS = 5 V)
100mV/DIV
INPUT
100mV/DIV
OUTPUT
1V/DIV
OUTPUT
INPUT COMMON MODE
40V/DIV
V
= 2.7V
S
TIME (2µs/DIV)
TIME (1µs/DIV)
Figure 20. Input Common-Mode Step Response Small Scale
(VS = 5 V, Inputs Shorted)
Figure 17. Differential Overload Recovery, Falling (VS = 2.7 V)
NO LOAD
330pF
470pF
1nF
200mV/DIV
100mV/DIV
100mV/DIV
100mV/DIV
100mV/DIV
INPUT
2V/DIV
OUTPUT
V
= 5V
S
TIME (4µs/DIV)
TIME (1µs/DIV)
Figure 21. Small Signal Response for Various Capacitive Loads
Figure 18. Differential Overload Recovery, Falling (VS = 5 V)
Rev. E | Page 8 of 18
Data Sheet
AD8418A
0
–50
45
40
35
30
25
20
15
10
5
2.7V
5V
–100
–150
–200
–250
–300
–350
–400
–450
–500
0
0
1
2
3
4
5
6
7
8
9
10
–40 –25 –10
5
20
35
50
65
80
95 110 125
OUTPUT SOURCE CURRENT (mA)
TEMPERATURE (°C)
Figure 22. Maximum Output Sink Current vs. Temperature
Figure 24. Output Voltage Range from Positive Rail vs. Output Source Current
40
35
30
25
20
15
10
5
300
250
200
150
100
50
5V
2.7V
0
0
–40 –25 –10
5
20
35
50
65
80
95 110 125
0
1
2
3
4
5
6
7
8
9
10
TEMPERATURE (°C)
OUTPUT SINK CURRENT (mA)
Figure 23. Maximum Output Source Current vs. Temperature
Figure 25. Output Voltage Range from Ground vs. Output Sink Current
Rev. E | Page 9 of 18
AD8418A
Data Sheet
1800
1500
1200
900
600
300
0
–40°C
V
= 5.0V
S
+25°C
1600
1400
1200
1000
800
600
400
200
0
+125°C
–400
–300
–200
–100
0
100
200
300
400
–3
–2
–1
0
1
V
(µV)
OS
GAIN ERROR DRIFT (ppm/°C)
Figure 28. Gain Error Drift Distribution
Figure 26. Offset Voltage Distribution
0.5
0.4
NORMALIZED AT 25°C
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
–40 –25 –10
5
20
35
50
65
80
95 110 125
TEMPERATURE (°C)
Figure 27. CMRR vs. Temperature
Rev. E | Page 10 of 18
Data Sheet
AD8418A
THEORY OF OPERATION
The AD8418A 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 voltages.
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 AD8418A measures current by
amplifying the voltage across a shunt resistor connected to its
inputs by a gain of 20 V/V (see Figure 29).
The AD8418A offers breakthrough performance without
compromising any of the robust application needs typical of
solenoid or motor control. The ability to reject PWM input
common-mode voltages and the zero drift architecture
providing low offset and offset drift allows the AD8418A to
deliver total accuracy for these demanding applications.
The AD8418A design provides excellent common-mode rejection,
even with PWM common-mode inputs that can change at very fast
rates, for example, 1 V/ns. The AD8418A contains proprietary
technology to eliminate the negative effects of such fast changing
external common-mode variations.
The AD8418A features an input offset drift of less than 400 nV/°C.
This performance is achieved through a novel zero drift
architecture that does not compromise bandwidth, which is
typically rated at 250 kHz.
V
= –2V TO +70V
V = 2.7V TO 5.5V
S
CM
70V
V
V
1
REF
S
V
OUT
V
AD8418A
V
S
CM
0V
+IN
–IN
EMI
+
–
FILTER
I
SHUNT
OUT
G = 20
R
SHUNT
V /2
S
EMI
FILTER
50A
SHUNT
–50A
I
0V
GND
V
2
REF
Figure 29. Typical Application
Rev. E | Page 11 of 18
AD8418A
Data Sheet
OUTPUT OFFSET ADJUSTMENT
The output of the AD8418A can be adjusted for unidirectional
or bidirectional operation.
VS Referenced Output Mode
VS referenced output 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 the wiring before
power is applied to the load (see Figure 31).
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8418A to measure
currents through a resistive shunt in one direction. The basic
modes for unidirectional operation are ground referenced output
mode and VS referenced output mode.
V
S
For unidirectional operation, the output can be set at the negative
rail (near ground) or at the positive rail (near VS) when the
differential input is 0 V. The output moves to the opposite rail
when a correct polarity differential input voltage is applied. 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 needs to be negative to decrease the output. If the output is
set at ground, the polarity must be positive to increase the output.
AD8418A
R1
R4
R3
–
+
–IN
+IN
OUT
R2
V
V
1
2
REF
REF
GND
Ground Referenced Output Mode
Figure 31. VS Referenced Output
When using the AD8418A in ground referenced output mode,
both referenced inputs are tied to ground, which causes the output
to sit at the negative rail when there are zero differential volts at the
input (see Figure 30).
BIDIRECTIONAL OPERATION
Bidirectional operation allows the AD8418A to measure currents
through a resistive shunt in two directions.
V
S
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 nonsymmetrical.
AD8418A
R1
R4
R3
–
+
–IN
+IN
OUT
Adjusting the output is accomplished by applying voltage(s) to
the referenced inputs. VREF1 and VREF2 are tied to internal resistors
that connect to an internal offset node. There is no operational
difference between the pins.
R2
V
1
2
REF
V
REF
GND
Figure 30. Ground Referenced Output
Rev. E | Page 12 of 18
Data Sheet
AD8418A
V
S
EXTERNAL REFERENCED OUTPUT
Tying VREF1 and VREF2 together and to a reference produces an
output equal to the reference voltage when there is no differential
input (see Figure 32). The output decreases with respect to the
reference voltage when the input is negative, relative to the
–IN pin, and increases when the input is positive, relative to
the −IN pin.
AD8418A
R1
R4
R3
–
+
–IN
+IN
OUT
R2
V
V
1
2
REF
REF
V
S
AD8418A
R1
GND
R4
R3
–
+
–IN
+IN
Figure 33. Split Supply
OUT
SPLITTING AN EXTERNAL REFERENCE
R2
V
V
1
2
REF
Use the internal reference resistors to divide an external reference
by 2 with an accuracy of approximately 0.5%. Split an external
reference by connecting one VREFx pin to ground and the other
REF
2.5V
VREFx pin to the reference (see Figure 34).
GND
V
S
Figure 32. External Referenced Output
SPLITTING THE SUPPLY
AD8418A
R1
By tying one reference pin to VS and the other to the ground pin,
the output is set at half of the supply when there is no differential
input (see Figure 33). The benefit of this configuration is that
an external reference is not required to offset the output for
bidirectional current measurement. Tying one reference pin to VS
and the other to the ground pin 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 increases to 2.75 V.
R4
R3
–
+
–IN
+IN
OUT
R2
V
V
1
2
REF
REF
5V
GND
Figure 34. Split External Reference
Rev. E | Page 13 of 18
AD8418A
Data Sheet
APPLICATIONS INFORMATION
MOTOR CONTROL
3-Phase Motor Control
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 can be made with
a simple ground referenced op amp. The AD8418A measures
current in both directions as the H-bridge switches and the motor
changes direction. The output of the AD8418A is configured in
an external referenced bidirectional mode (see the Bidirectional
Operation section).
The AD8418A is ideally suited for monitoring current in
3-phase motor applications.
The 250 kHz typical bandwidth of the AD8418A provides
instantaneous current monitoring. Additionally, the typical
low offset drift of 0.1 μV/°C means that the measurement error
between the two motor phases is at a minimum over temperature.
The AD8418A rejects PWM input common-mode voltages in
the −2 V to +70 V (with a 5 V supply) range. Monitoring the
current on the motor phase allows sampling of the current at
any point and provides diagnostic information, such as a short to
GND and battery. Refer to Figure 36 for the typical phase
current measurement setup with the AD8418A.
CONTROLLER
5V
+IN
V
OUT
NC
V
1
REF
S
MOTOR
AD8418A
5V
SHUNT
–IN GND
V
2
REF
2.5V
H-Bridge Motor Control
Another typical application for the AD8418A is to form part of
the control loop in H-bridge motor control. In this case, place
the shunt resistor in the middle of the H-bridge to accurately
measure current in both directions by using the shunt available
at the motor (see Figure 35). Using an amplifier and shunt in
this location is a better solution than a ground referenced op
Figure 35. H-Bridge Motor Control
V+
M
I
I
I
U
V
W
V–
5V
5V
INTERFACE
AD8214
CIRCUIT
AD8418A
AD8418A
OPTIONAL
DEVICE FOR
OVERCURRENT
PROTECTION AND
FAST (DIRECT)
SHUTDOWN OF
POWER STAGE
CONTROLLER
BIDIRECTIONAL CURRENT MEASUREMENT
REJECTION OF HIGH PWM COMMON-MODE VOLTAGE (–2V TO +70V)
AMPLIFICATION
HIGH OUTPUT DRIVE
Figure 36. 3-Phase Motor Control
Rev. E | Page 14 of 18
Data Sheet
AD8418A
5V
SOLENOID CONTROL
High-Side Current Sense with a Low-Side Switch
SWITCH
OUTPUT
In the case of a high-side current sense with a low-side switch,
the PWM control switch is ground referenced. Tie an inductive
load (solenoid) to a power supply and place a resistive shunt
between the switch and the load (see Figure 37). An advantage
of placing the shunt on the high side is that the entire current,
including the recirculation current, is measurable because the
shunt remains in the loop when the switch is off. In addition,
diagnostics are enhanced because shorts to ground are detected
with the shunt on the high side.
+
–
8
7
6
5
BATTERY
AD8418A
SHUNT
CLAMP
DIODE
INDUCTIVE
LOAD
1
2
3
4
In this circuit configuration, when the switch is closed, the
common-mode voltage decreases to near the negative rail. When
the switch is open, 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.
NC = NO CONNECT.
Figure 38. High-Side Switch
High Rail Current Sensing
In the high rail, current sensing configuration, the shunt resistor is
referenced to the battery. High voltage is present at the inputs of
the current sense amplifier. When the shunt is battery referenced,
the AD8418A produces a linear ground referenced analog output.
Additionally, the AD8214 provides an overcurrent detection
signal in as little as 100 ns (see Figure 39). This feature is useful
in high current systems where fast shutdown in overcurrent
conditions is essential.
5V
OUTPUT
CLAMP
DIODE
INDUCTIVE
LOAD
+
–
8
7
6
5
BATTERY
SHUNT
AD8418A
SWITCH
1
2
3
4
OVERCURRENT
DETECTION (<100ns)
OUTPUT
8
7
6
5
NC = NO CONNECT.
Figure 37. Low-Side Switch
AD8214
High-Side Current Sense with a High-Side Switch
The high-side current sense with a high-side switch configuration
minimizes the possibility of unexpected solenoid activation and
excessive corrosion (see Figure 38). 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 shorts to ground while still allowing the recirculating
current to be measured and to provide diagnostics. Removing the
power supply from the load for the majority of the time that the
switch is open minimizes the corrosive effects that can be caused
by the differential voltage between the load and ground.
1
2
3
4
CLAMP
DIODE
SHUNT
+
–
+IN
–IN
1
2
3
4
8
7
6
5
INDUCTIVE
LOAD
V
1
GND
REF
S
AD8418A
V
V
2
TOP VIEW
REF
(Not to Scale)
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. In this case, when the
switch is open, the voltage reversal across the inductive load
causes the common-mode voltage to be held one diode drop
below ground by the clamp diode.
5V
NC
OUT
SWITCH
NC = NO CONNECT.
Figure 39. High Rail Current Sensing
Rev. E | Page 15 of 18
AD8418A
Data Sheet
NC pins are inserted between −IN and GND, as well as between
+IN and VREF1. These NC pins effectively isolate the voltages at
the input pins, which may range from −2 V to +70 V, from
adjacent pins that prevent the occurrence of unrecoverable faults.
PINOUT OPTION ENGINEERED FOR FMEA
The AD8418A is available in a 10-lead MSOP pinout option
engineered for FMEA. This FMEA tolerant pinout is designed
to meet stringent automotive requirements and to conditionally
survive single faults that are a result of common printed circuit
board (PCB) defects, as described in Table 6 and Table 7.
Table 6. Behavior as a Result of Adjacent Pin to Pin Shorts
Pin Number Adjacent Pins Shorted Behavior
1, 2
2, 3
3, 4
−IN and NC
NC and GND
GND and VREF
The circuit behaves normally.
The circuit behaves normally.
The operating range of VREF2 is from GND to VS. Therefore, shorting VREF2 to GND does not
represent a fault. For example, if the AD8418A references are configured to split the supply with
2
V
REF2 tied to GND, the circuit behaves normally. A system error occurs, however, if VREF2 is tied
either to VS or to a different external reference because GND is shorted to VS or to the external
reference voltage on the PCB.
4, 5
6, 7
7, 8
VREF2 and NC
OUT and VS
The circuit behaves normally.
OUT approaches VS voltage.
The operating range of VREF1 is from GND to VS. Therefore, shorting VREF1 to VS does not represent
a fault. For example, if the AD8418A references are configured to split the supply with VREF1 tied
to VS, the circuit behaves normally. A system error occurs, however, if VREF1 is tied either to GND
or to a different external reference because VS is shorted to GND or to the external reference
voltage on the PCB.
VS and VREF
1
8, 9
9, 10
VREF1 and NC
NC and +IN
The circuit behaves normally.
The circuit behaves normally.
Table 7. Behavior as a Result of Open Pin, Split Supply Setup (VREF1 to VS and VREF2 to GND), VS – 5 V, −IN = +IN = 12 V
Pin Number
Pin Opened
Behavior
1
2
3
−IN
NC
GND
OUT is undetermined but is limited between GND and VS.
The circuit behaves normally.
The output voltage range is limited to 0.7 V to VS and the device receives the ground through an ESD
diode on VREF2.
4
5
6
7
VREF
NC
OUT
VS
2
OUT approaches VS.
The circuit behaves normally.
No OUT signal.
The device is powered through an ESD diode between the VREF1 pin and VS pin. The output voltage range
is limited to GND to VS − 0.7 V.
8
9
VREF
NC
1
OUT approaches GND.
The circuit behaves normally.
10
+IN
OUT is undetermined but is limited between GND and VS.
Rev. E | Page 16 of 18
Data Sheet
AD8418A
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 40. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
3.20
3.00
2.80
8
1
5
4
5.15
4.90
4.65
3.20
3.00
2.80
PIN 1
IDENTIFIER
0.65 BSC
0.95
0.85
0.75
15° MAX
1.10 MAX
0.80
0.55
0.40
0.15
0.05
0.23
0.09
6°
0°
0.40
0.25
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 41. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
Rev. E | Page 17 of 18
AD8418A
Data Sheet
3.10
3.00
2.90
10
1
6
5
5.15
4.90
4.65
3.10
3.00
2.90
PIN 1
IDENTIFIER
0.50 BSC
0.95
0.85
0.75
15° MAX
1.10 MAX
0.70
0.55
0.40
0.15
0.05
0.23
0.13
6°
0°
0.30
0.15
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-BA
Figure 42. 10-Lead Mini Small Outline Package [MSOP]
(RM-10)
Dimensions shown in millimeters
ORDERING GUIDE
Model1, 2
AD8418ABRMZ
AD8418ABRMZ-RL
AD8418AWBRMZ
AD8418AWBRMZ-RL
AD8418AWBRZ
AD8418AWBRZ-RL
AD8418AWHRZ
AD8418AWHRZ-RL
AD8418AWHRMZ
AD8418AWHRMZ-RL
AD8418AWBRMZ-10
AD8418AWBRMZ-10RL
AD8418AR-EVALZ
AD8418ARM-EVALZ
Temperature Range
Package Description
Package Option
RM-8
RM-8
RM-8
RM-8
R-8
R-8
R-8
R-8
RM-8
RM-8
RM-10
RM-10
Marking Code
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +150°C
−40°C to +150°C
−40°C to +150°C
−40°C to +150°C
−40°C to +125°C
−40°C to +125°C
8-Lead MSOP
8-Lead MSOP, 13” Tape and Reel
8-Lead MSOP
8-Lead MSOP, 13” Tape and Reel
8-Lead SOIC_N
8-Lead SOIC_N, 13” Tape and Reel
8-Lead SOIC_N
8-Lead SOIC_N, 13” Tape and Reel
8-Lead MSOP
8-Lead MSOP, 13” Tape and Reel
10-lead MSOP
10-lead MSOP, 13” Tape and Reel
8-Lead SOIC_N Evaluation Board
8-Lead MSOP Evaluation Board
Y5J
Y5J
Y5G
Y5G
Y5H
Y5H
A3Z
A3Z
1 Z = RoHS Compliant Part.
2 W = Qualified for Automotive Applications.
AUTOMOTIVE PRODUCTS
The AD8418AW 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.
©2013–2020 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D11883-6/20(E)
Rev. E | Page 18 of 18
相关型号：
©2020 ICPDF网 联系我们和版权申明