ad538sd-883b Analog Devices, Inc., ad538sd-883b Datasheet

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ad538sd-883b

Manufacturer Part Number
ad538sd-883b
Description
Real-time Analog Computational Unit Acu
Manufacturer
Analog Devices, Inc.
Datasheet
a
PRODUCT DESCRIPTION
The AD538 is a monolithic real-time computational circuit that
provides precision analog multiplication, division and exponen-
tiation. The combination of low input and output offset voltages
and excellent linearity results in accurate computation over an
unusually wide input dynamic range. Laser wafer trimming makes
multiplication and division with errors as low as 0.25% of read-
ing possible, while typical output offsets of 100 V or less add to
the overall off-the-shelf performance level. Real-time analog
signal processing is further enhanced by the device’s 400 kHz
bandwidth.
The AD538’s overall transfer function is V
Programming a particular function is via pin strapping. No
external components are required for one-quadrant (positive
input) multiplication and division. Two-quadrant (bipolar
numerator) division is possible with the use of external level
shifting and scaling resistors. The desired scale factor for both
multiplication and division can be set using the on-chip +2 V or
+10 V references, or controlled externally to provide simulta-
neous multiplication and division. Exponentiation with an m
value from 0.2 to 5 can be implemented with the addition of
one or two external resistors.
REV. C
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.
FEATURES
V
Wide Dynamic Range (Denominator) –1000:1
Simultaneous Multiplication and Division
Resistor-Programmable Powers and Roots
No External Trims Required
Low Input Offsets <100
Low Error
+2 V and +10 V On-Chip References
Monolithic Construction
APPLICATIONS
One- or Two-Quadrant Mult/Div
Log Ratio Computation
Squaring/Square Rooting
Trigonometric Function Approximations
Linearization Via Curve Fitting
Precision AGC
Power Functions
OUT
= V
Y
V
V
0.25% of Reading (100:1 Range)
X
Z
m
Transfer Function
V
O
= V
Y
(V
Z
/ V
X
)
m
.
Direct log ratio computation is possible by using only the log
ratio and output sections of the chip. Access to the multiple
summing junctions adds further to the AD538’s flexibility.
Finally, a wide power supply range of 4.5 V to 18 V allows
operation from standard 5 V, 12 V and 15 V supplies.
The AD538 is available in two accuracy grades (A and B) over
the industrial (–25 C to +85 C) temperature range and one
grade (S) over the military (–55 C to +125 C) temperature
range. The device is packaged in an 18-lead TO-118 hermetic
side-brazed ceramic DIP. A-grade chips are also available.
PRODUCT HIGHLIGHTS
1. Real-time analog multiplication, division and exponentiation.
2. High accuracy analog division with a wide input dynamic
3. On-chip +2 V or +10 V scaling reference voltages.
4. Both voltage and current (summing) input modes.
5. Monolithic construction with lower cost and higher reliability
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
range.
than hybrid and modular circuits.
+10V
+2V
+V
–V
V
V
I
B
S
S
O
Z
Z
I
1
2
3
4
5
6
7
8
9
Computational Unit (ACU)
FUNCTIONAL BLOCK DIAGRAM
25k
OUTPUT
25k
REFERENCE
INTERNAL
VOLTAGE
World Wide Web Site: http://www.analog.com
100
ANTILOG
RATIO
LOG
Real-Time Analog
AD538
LOG
100
© Analog Devices, Inc., 1999
25k
25k
AD538
18
17
16
15
14
13
12
11
10
A
D
I
V
SIGNAL
GND
PWR
GND
C
I
V
X
Y
X
Y

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ad538sd-883b Summary of contents

Page 1

... FUNCTIONAL BLOCK DIAGRAM 1 LOG 25k RATIO 25k 100 100 5 INTERNAL VOLTAGE 6 AD538 REFERENCE 7 OUTPUT 25k 8 ANTILOG I 9 LOG 25k World Wide Web Site: http://www.analog.com © Analog Devices, Inc., 1999 SIGNAL 14 GND PWR 13 GND ...

Page 2

... AD538SD AD538SD/883B Units % of Reading + Reading + Reading + )/ Reading + )/ kHz V/V V/V ...

Page 3

RE-EXAMINATION OF MULTIPLIER/DIVIDER ACCURACY Traditionally, the “accuracy” (actually the errors) of analog multipliers and dividers have been specified in terms of percent of full scale. Thus specified multiplier error with full-scale output would mean a ...

Page 4

... Model AD538AD AD538BD AD538ACHIPS AD538SD AD538SD/883B 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 AD538 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 ...

Page 5

OFFSET 1.0 0 –55 –40 – TEMPERATURE – C Figure 1. Multiplier Error vs. Temperature (100 mV < 5.0 4.0 3.0 2.0 ...

Page 6

AD538 150 100 V = 10V +5V SIN 1.0 0.1 100 1k 10k INPUT FREQUENCY – Hz Figure 7. V Feedthrough vs. Frequency LOG 25k RATIO ...

Page 7

STABILITY PRECAUTIONS At higher frequencies, the multistaged signal path of the AD538, as illustrated in Figure 10, can result in large phase shifts condition of high incremental gain exists along that path (e.g ...

Page 8

AD538 TWO-QUADRANT DIVISION The two-quadrant linear divider circuit illustrated in Figure 13 uses the same basic connections as the one-quadrant version. However, in this circuit the numerator has been offset in the positive direction by adding the denominator input voltage ...

Page 9

ANALOG COMPUTATION OF POWERS AND ROOTS It is often necessary to raise the quotient of two input signals to a power or take a root. This could be squaring, cubing, square- rooting or exponentiation to some noninteger power. Examples include ...

Page 10

AD538 TRANSDUCER LINEARIZATION Many electronic transducers used in scientific, commercial or industrial equipment monitor the physical properties of a device and/or its environment. Sensing (and perhaps compensating for) changes in pressure, temperature, moisture or other physical phenomenon can be an ...

Page 11

REV. C OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Side-Brazed Ceramic DIP (D-18 0.30 (7.62) 0.28 (7.12 PIN 1 0.306 (7.78) 0.91 (23.12) 0.294 (7.47) 0.89 (22.61) 0.175 (4.45) MAX 0.125 (3.18) 0.02 ...

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