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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 k Drives 1 k 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: -40 C to +125 C APPLICATIONS Interface for Pressure Transducers, Position Indicator, Strain Gages and Other Low Level Signal Sources
IN+ 8
Single Supply Bridge Transducer Amplifier AD22055
FUNCTIONAL BLOCK DIAGRAM
+VS 6 OFS 7 FILT 3
AD22055
A1 IN- 1 A2 5 OUT
4 GAIN 2 GND
GENERAL DESCRIPTION
The AD22055 accepts a differential signal from a bridge transducer whose common-mode signal can be anywhere between the power supplies.
The extended temperature range allows for local signal conditioning for oil and hydraulic pressure sensors as well as other automotive sensors. 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
IN- GND FILT GAIN 1 2 3 4 1k
GAIN = 400
ANALOG GROUND
Figure 1. Typical Application Circuit for a Pressure Sensor Interface
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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 (c) Analog Devices, Inc., 1997
AD22055-SPECIFICATIONS (@ T = + 25 C, V = +5 V, V
A S
CM
= 0, unless otherwise noted)
Min 0 -80 -60 180 180 Typ Max 5 -90 -75 230 0.5 230 40 +0.02 77.6 80 10 2.0 398 400 -60 -500 0.05 1 -10 3.0 11 30 0.2 0.2 5 200 402 Units V dB dB k % k
Parameter INPUTS (PINS 1 AND 8) VCM CMRRLF CMRRHF RINCM RMATCH RINDIFF PREAMPLIFIER GCL VO RO OUTPUT BUFFER GCL VO RO OVERALL SYSTEM GCL VOS
Comments Common-Mode Range Common-Mode Rejection Ratio Common-Mode Rejection Ratio Common-Mode Input Resistance Matching of Input Resistances Differential Input Resistance Closed-Loop Gain1 Output Voltage Range (Pin 3) Output Resistance2 Closed-Loop Gain1 Output Voltage Range Output Resistance (Pin 5) 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 Operating Range Quiescent Supply Current4 Operating Temperature Range
Test Conditions
f 10 Hz f = 10 kHz Pin 1 or Pin 8 to Pin 2 Pin 1 to Pin 8
300
V/V +4.75 V 82.4 k 10.05 +4.75 V/V V V/V ppm/C ppm/C mV V/C V/C k mA kHz V/s V/Hz V A C
RLOAD 10 k VO 0.1 V dc VO 0.1 V dc -40C to +125C -125C to +150C -40C to +125C -125C to +150C Pin 7 to Pin 2 VO = + 1 V dc f = 100 Hz to 10 kHz TA = TMIN to TMAX
9.95 +0.02
-1
1
IOSC BW-3 dB SR NSD POWER SUPPLY VS IS TEMPERATURE RANGE TOP
2.5 7 20
25
3
36 500 +125
-40
NOTES 1 A2 gain is trimmed to 0.5% with a 0.01% 1 k resistor to ground from Pin 4. The overall gain is trimmed to a gain of 400 0.5% with the same 1 k 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 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.
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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 . . . . . . . . . . . . . . . . -40C to +125C Storage Temperature . . . . . . . . . . . . . . . . . . -65C to +150C Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . +300C
1
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. 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. 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 k 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 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:
9 k Gain = 40 1 + RGAIN V/V
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 Temperature Range Package Description Package Option*
Model
AD22055N AD22055R
-40C to +125C
Plastic DIP Plastic SOIC
N-8 SO-8
*N = Plastic DIP; SO = Small Outline Package.
PIN CONNECTION
IN- 1 GND 2 8 IN+
7 OFS TOP VIEW FILT 3 (Not to Scale) 6 +VS 5 OUT
AD22055
GAIN 4
(1)
PIN DESCRIPTION
Pin 1 2 3 4 5 6 7 8
8-Pin SOIC Function IN- Ground Filter Gain Out +VS OFS IN+
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.
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.
WARNING!
ESD SENSITIVE DEVICE
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AD22055
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP (N-8)
C2978-12-1/97
0.195 (4.95) 0.115 (2.93) 0.430 (10.92) 0.348 (8.84)
8 5
0.280 (7.11) 0.240 (6.10)
1 4
PIN 1 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.93)
0.060 (1.52) 0.015 (0.38) 0.130 (3.30) MIN SEATING PLANE
0.325 (8.25) 0.300 (7.62)
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)
8-Lead Plastic SOIC Package (SO-8)
0.1968 (5.00) 0.1890 (4.80)
8 1 5 4
0.1574 (4.00) 0.1497 (3.80)
0.2440 (6.20) 0.2284 (5.80)
PIN 1 0.0098 (0.25) 0.0040 (0.10)
0.0688 (1.75) 0.0532 (1.35)
0.0196 (0.50) x 45 0.0099 (0.25)
SEATING PLANE
0.0500 0.0192 (0.49) (1.27) 0.0138 (0.35) BSC
0.0098 (0.25) 0.0075 (0.19)
8 0
0.0500 (1.27) 0.0160 (0.41)
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PRINTED IN U.S.A.

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