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PDF AD8418A Data sheet ( Hoja de datos )
| Número de pieza | AD8418A | |
| Descripción | Current Sense Amplifier | |
| Fabricantes | Analog Devices | |
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Data Sheet
Bidirectional, Zero Drift,
Current Sense Amplifier
AD8418A
FEATURES
Typical 0.1 μV/°C offset drift
Maximum ±400 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
−4 V to +85 V survival
Common-mode rejection ratio (CMRR): 86 dB, dc to 10 kHz
Initial gain = 20 V/V
Wide operating temperature range
AD8418AWB: −40°C to +125°C
AD8418AWH: −40°C to +150°C
Bidirectional operation
Available in 8-lead SOIC and 8-lead MSOP
Qualified for automotive applications
APPLICATIONS
High-side current sensing in
Motor controls
Solenoid controls
Power management
Low-side current sensing
Diagnostic protection
GENERAL DESCRIPTION
The AD8418A is a high voltage, high resolution current shunt
amplifier. It features an initial gain of 20 V/V, with a maximum
±0.2% 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. The 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.
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 ±200 μV. The AD8418A is offered in 8-lead MSOP and SOIC
packages.
Table 1. Related Devices
Part No. Description
AD8205 Current sense amplifier, gain = 50
AD8206 Current sense amplifier, gain = 20
AD8207 High accuracy current sense amplifier, gain = 20
AD8210 High speed current sense amplifier, gain = 20
AD8417 High accuracy current sense amplifier, gain = 60
70V
VCM
0V
50A
ISHUNT
–50A
VCM = –2V TO +70V
FUNCTIONAL BLOCK DIAGRAM
VS = 2.7V TO 5.5V
VS VREF1
ISHUNT
+IN
RSHUNT
–IN
EMI
FILTER
EMI
FILTER
+
G = 20
–
AD8418A
OUT
VS
VS/2
GND
VREF2
Figure 1.
0V
VOUT
Rev. A
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.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2013–2014 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
1 page  
AD8418A
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
Supply Voltage
Input Voltage Range
Continuous
Survival
Differential Input Survival
Reverse Supply Voltage
ESD Human Body Model (HBM)
Operating Temperature Range
AD8418AWB
AD8418AWH
Storage Temperature Range
Output Short-Circuit Duration
Rating
6V
−2 V to +70 V
−4 V to +85 V
±5.5 V
0.3 V
±2000 V
−40°C to +125°C
−40°C to +150°C
−65°C to +150°C
Indefinite
Data Sheet
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.
ESD CAUTION
Rev. A | Page 4 of 16
5 Page 
AD8418A
Data Sheet
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.
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 26).
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.
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.
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.
70V
VCM
0V
50A
ISHUNT
–50A
VCM = –2V TO +70V
ISHUNT
+IN
RSHUNT
–IN
EMI
FILTER
EMI
FILTER
VS = 2.7V TO 5.5V
VS VREF1
AD8418A
+
G = 20
OUT
–
VS
VS/2
GND
VREF2
Figure 26. Typical Application
0V
VOUT
Rev. A | Page 10 of 16
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet AD8418A.PDF ] | |
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