AD AD22055N

Single Supply Bridge
Transducer Amplifier
AD22055
a
FEATURES
Gain of 400. Alterable from 40 to 1000
Output Span 20 mV to (VS – 0.25) V
1 Pole Low-Pass Filtering Available
Offset Capability
Differential Input Resistance 230 kV
Drives 1 kV Load to +4 V Using VS = +5 V
Supply Voltage: +3 V to +36 V
Transient Spike Protection and RFI Filters Included
Peak Input Voltage (40 ms): 60 V
Reversed Supply Protection: –34 V
Operating Temperature Range: –408C to +1258C
FUNCTIONAL BLOCK DIAGRAM
+VS
OFS
FILT
6
7
3
AD22055
IN+ 8
A1
IN– 1
A2
5 OUT
4 GAIN
2
APPLICATIONS
Interface for Pressure Transducers, Position
Indicator, Strain Gages and Other Low Level Signal
Sources
GND
The extended temperature range allows for local signal conditioning for oil and hydraulic pressure sensors as well as other
automotive sensors.
GENERAL DESCRIPTION
The AD22055 accepts a differential signal from a bridge transducer whose common-mode signal can be anywhere between
the power supplies.
The use of an external gain resistor allows the user to compensate transducer gain error and temperature drift.
+5 VOLT
VREF
OUTPUT
8
7
6
5
IN+ OFS +VS OUT
AD22055
GAIN = 400
IN– GND FILT GAIN
1
2
3
4
1kΩ
ANALOG
GROUND
Figure 1. Typical Application Circuit for a Pressure Sensor Interface
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
AD22055–SPECIFICATIONS (@ T = + 258C, V = +5 V, V
A
S
Parameter
Comments
INPUTS (PINS 1 AND 8)
VCM
CMRRLF
CMRRHF
RINCM
RMATCH
RINDIFF
Common-Mode Range
Common-Mode Rejection Ratio
Common-Mode Rejection Ratio
Common-Mode Input Resistance
Matching of Input Resistances
Differential Input Resistance
PREAMPLIFIER
GCL
VO
RO
Closed-Loop Gain1
Output Voltage Range (Pin 3)
Output Resistance2
OUTPUT BUFFER
GCL
VO
RO
Closed-Loop Gain1
Output Voltage Range
Output Resistance (Pin 5)
OVERALL SYSTEM
GCL
VOS
IOSC
BW–3 dB
SR
NSD
Gain1
Gain Drift
Gain Drift
Initial Offset Voltage3
Offset Drift
Offset Drift
Input Resistance
Short-Circuit Output Current
–3 dB Bandwidth
Slew Rate
Noise Spectral Density3
POWER SUPPLY
VS
IS
Operating Range
Quiescent Supply Current4
TEMPERATURE RANGE
TOP
Operating Temperature Range
CM
= 0, unless otherwise noted)
Test Conditions
Min
f ≤ 10 Hz
f = 10 kHz
Pin 1 or Pin 8 to Pin 2
0
–80
–60
180
Pin 1 to Pin 8
180
Typ
–90
–75
230
± 0.5
230
40
+0.02
77.6
RLOAD ≥ 10 kΩ
VO ≥ 0.1 V dc
VO ≥ 0.1 V dc
–40°C to +125°C
–125°C to +150°C
9.95
+0.02
VO = + 1 V dc
398
2.5
7
20
f = 100 Hz to 10 kHz
TA = TMIN to TMAX
10
Units
5
V
dB
dB
kΩ
%
kΩ
300
V/V
+4.75 V
82.4
kΩ
10.05
+4.75
V/V
V
Ω
402
V/V
ppm/°C
ppm/°C
mV
µV/°C
µV/°C
kΩ
mA
kHz
V/µs
µV/√Hz
2.0
–1
–40°C to +125°C
–125°C to +150°C
Pin 7 to Pin 2
80
Max
3
–40
400
–60
–500
0.05
1
–10
3.0
11
30
0.2
0.2
5
200
1
25
36
500
V
µA
+125
°C
NOTES
1
A2 gain is trimmed to ± 0.5% with a 0.01% 1 kΩ resistor to ground from Pin 4. The overall gain is trimmed to a gain of 400 ± 0.5% with the same 1 kΩ resistor. The
gain of A1 (the ratio of overall gain to A2 gain) is used to adjust the overall gain and, therefore, is not trimmed explicitly to 40. Note that the actual gain to a particular application can be modified by the use of an external resistor at Pin 4.
2
The actual output resistance of A1 is only a few ohms, but access to this output, via Pin 3, is always through an 80 k Ω resistor, which is trimmed to ± 3%.
3
Referred to the input (Pins 1 and 8).
4
With VDM = 0 V. Differential mode signals are referred to as V DM, while VCM refers to common-mode voltages.
All min and max specifications are guaranteed, although only those marked in boldface are tested on all production units at final test.
Specifications subject to change without notice.
–2–
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AD22055
ABSOLUTE MAXIMUM RATINGS 1
PRODUCT DESCRIPTION
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . +3 V to +36 V
Peak Input Voltage (40 ms) . . . . . . . . . . . . . . . . . . . . . . . . 60 V
Reversed Continuous Supply Voltage . . . . . . . . . . . . . . –34 V
Operating Temperature . . . . . . . . . . . . . . . . –40°C to +125°C
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +150°C
Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . +300°C
The AD22055 is a single supply difference amplifier consisting
of a precision balanced attenuator, a very low drift preamplifier
and an output buffer amplifier (A1 and A2, respectively, in the
functional block diagram). It has been designed so that small
differential signals, VDM, can be accurately amplified and filtered in the presence of large common-mode voltages, VCM,
without the use of any other active components.
1
The common-mode range resistors in this network are trimmed
to match better than one part in 10,000. The resistive attenuator network is situated at the input to the AD22055 (Pins 1
and 8) allowing the common-mode voltage at Pins 1 and 8 to be
two times greater than that which can be tolerated by the actual
input of A1. As a result, the input common-mode range extends
from ground to the power supply voltage.
Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only; the functional
operation of the device at these or any other conditions above those indicated in the
operation sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
ORDERING GUIDE
Model
Temperature
Range
Package
Description
Package
Option*
AD22055N
AD22055R
–40°C to +125°C
Plastic DIP
Plastic SOIC
N-8
SO-8
Two small filter capacitors (not shown) have been included at
the inputs to A1 to minimize the effects of any spurious RF signals present in the signal.
Internal feedback around A1 sets the closed-loop gain of the
preamplifier to 40 V/V from the input pins, and the output of
A1 is connected to Pin 3 via a 80 kΩ resistor, which is trimmed
to ± 3% to facilitate the low-pass filtering of the signal. The output buffer A2 has a gain of 10 V/V (using a precise 1 kΩ resistor
from Pin 4 to ground) setting the precalibrated, overall gain of
the AD22055, to 400 V/V. This gain is easily user-configurable.
*N = Plastic DIP; SO = Small Outline Package.
PIN CONNECTION
8 IN+
IN– 1
GND 2
Overall gain is programmed using the following equation:
AD22055
7 OFS
TOP VIEW
FILT 3 (Not to Scale) 6 +VS
GAIN 4

9 kΩ
Gain = 40  1 +
RGAIN

5 OUT
1
2
3
4
5
6
7
8
8-Pin SOIC
Function
IN–
Ground
Filter
Gain
Out
+VS
OFS
IN+
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD22055 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
REV. 0
(1)
The dynamic properties of the AD22055 are optimized for
interfacing to transducers, particularly those with a Wheatstone
Bridge configuration. Its rejection of large, high frequency,
common-mode signals makes it superior to that of many alternative approaches. This is due to the very careful design of
the input attenuator and the integration of this highly balanced,
high impedance system with the preamplifier.
PIN DESCRIPTION
Pin

 V/V

–3–
WARNING!
ESD SENSITIVE DEVICE
AD22055
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP
(N-8)
8
C2978–12–1/97
0.430 (10.92)
0.348 (8.84)
5
0.280 (7.11)
0.240 (6.10)
1
4
0.060 (1.52)
0.015 (0.38)
PIN 1
0.210 (5.33)
MAX
0.325 (8.25)
0.300 (7.62)
0.195 (4.95)
0.115 (2.93)
0.130
(3.30)
MIN
0.160 (4.06)
0.115 (2.93)
0.022 (0.558) 0.100 0.070 (1.77)
0.014 (0.356) (2.54) 0.045 (1.15)
BSC
0.015 (0.381)
0.008 (0.204)
SEATING
PLANE
8-Lead Plastic SOIC Package
(SO-8)
0.1968 (5.00)
0.1890 (4.80)
0.1574 (4.00)
0.1497 (3.80)
PIN 1
SEATING
PLANE
5
1
4
0.2440 (6.20)
0.2284 (5.80)
0.0688 (1.75)
0.0532 (1.35)
0.0500 0.0192 (0.49)
(1.27) 0.0138 (0.35)
BSC
0.0196 (0.50)
x 45°
0.0099 (0.25)
0.0098 (0.25)
0.0075 (0.19)
8°
0°
0.0500 (1.27)
0.0160 (0.41)
PRINTED IN U.S.A.
0.0098 (0.25)
0.0040 (0.10)
8
–4–
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