ad22055r Analog Devices, Inc., ad22055r Datasheet - Page 3

• Manufacturer Part Number: ad22055r
• Description: Single Supply Bridge Transducer Amplifier
• Manufacturer: Analog Devices, Inc.

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ABSOLUTE MAXIMUM RATINGS
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
1
Model
AD22055N
AD22055R
*N = Plastic DIP; SO = Small Outline Package.
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.
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.
Temperature
Range
–40 C to +125 C
Pin
1
2
3
4
5
6
7
8
GAIN
GND
FILT
ORDERING GUIDE
PIN CONNECTION
PIN DESCRIPTION
IN–
8-Pin SOIC
1
2
3
4
(Not to Scale)
AD22055
TOP VIEW
Function
IN–
Ground
Filter
Gain
Out
+V
OFS
IN+
Package
Description
Plastic DIP
Plastic SOIC
1
8
7
6
5
S
IN+
OFS
+V
OUT
S
Package
Option*
N-8
SO-8
–3–
PRODUCT DESCRIPTION
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, V
tered in the presence of large common-mode voltages, V
without the use of any other active components.
The common-mode range resistors in this network are trimmed
to match better than one part in 10,000. The resistive attenua-
tor 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.
Two small filter capacitors (not shown) have been included at
the inputs to A1 to minimize the effects of any spurious RF sig-
nals 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 k resistor, which is trimmed
to 3% to facilitate the low-pass filtering of the signal. The out-
put buffer A2 has a gain of 10 V/V (using a precise 1 k resistor
from Pin 4 to ground) setting the precalibrated, overall gain of
the AD22055, to 400 V/V. This gain is easily user-configurable.
Overall gain is programmed using the following equation:
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 alter-
native 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.
Gain
40 1
DM
, can be accurately amplified and fil-
R
9 k
GAIN
V/V
WARNING!
ESD SENSITIVE DEVICE
AD22055
CM
,
(1)