Low Cost, 14-Bit, Dual Channel
Synchro/Resolver-to-Digital Converter
Data Sheet
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FEATURES
Low per-channel cost
32-lead DIL hybrid package
2.6 arc minute accuracy
14-bit resolution
Built-in test
Independent reference inputs
High tracking rate
APPLICATIONS
Gimbal/gyro control systems
Robotics
Engine controllers
Coordinate conversion
Military servo control systems
Fire control systems
Avionic systems
Antenna monitoring
CNC machine tooling
GENERAL DESCRIPTION
The AD2S44 is a 14-bit dual channel, continuous tracking synchro/
resolver-to-digital converter. It has been designed specifically
for applications where space, weight, and cost are at a premium.
Each 32-lead hybrid device contains two independent Type II servo
loop tracking converters. The ratiometric conversion technique
employed provides excellent noise immunity and tolerance of
long lead lengths.
The core of each conversion is performed by state-of-the-art mono-
lithic, integrated circuits manufactured by the Analog Devices, Inc.,
proprietary BiMOS II process, which combines the advantages of
low power CMOS digital logic with bipolar linear circuits. The
use of these ICs keeps the internal component count low and
ensures high reliability.
The built-in test (
BIT
) facility can be used in failsafe systems to
provide an indication of whether the converter is tracking
accurately.
Each channel incorporates a high accuracy differential condi-
tioning circuit for signal inputs providing more than 74 dB of
common-mode rejection. Options are available for both synchro
and resolver format inputs. The converter output is via a three-state
transparent latch allowing data to be read without interruption
of the converter operation. The A/
B
and
OE
control lines select
the channel and present the digital position to the common
data outputs.
The AD2S44 also features independent reference inputs where
different reference frequencies can be used for each channel.
All components are 100% tested at −55°C, +25°C, and +125°C.
Devices are processed to high reliability screening standards
and receive further levels of testing and screening to ensure
high levels of reliability.
FUNCTIONAL BLOCK DIAGRAM
AD2S44
REFERENCE
CONDITIONER
SYNCHRO/
RESOLVER
CONDITIONER
PHASE-
SENSITIVE
DETECTOR
THREE-
STATE
OUTPUT
LATCHES
DB1 (MSB)
TO
DB14 (LSB)
PHASE-
SENSITIVE
DETECTOR
HIGH
SPEED
SIN/COS
MULTIPLIER
BUILT-IN
TEST
DETECTION
ERROR
AMP
UP-DOWN
COUNTER
UP-DOWN
COUNTER
INTEGRATOR VCO
VCO
INTEGRATOR
ERROR
AMP
HIGH
SPEED
SIN/COS
MULTIPLIER
SYNCHRO/
RESOLVER
CONDITIONER
REFERENCE
CONDITIONER
S3 (A)
R
HI
(A)
R
LO
(A)
R
HI
(B)
R
LO
(B)
+V
S
–V
S
GND
S4 (A)
S1 (A)
S2 (A)
S3 (B)
S4 (B)
S1 (B)
S2 (B)
OE
A/B
BIT
02947-001
Figure 1.
