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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.
a
Programmable
Oscillator
FUNCTIONAL BLOCK DIAGRAM
FREQUENCY
SELECT
SINE WAVE
GENERATOR
PHASE
DETECT
LOGIC
SIN COS
FROM
TRANSDUCER
FBIAS
SEL1
SEL2
AD2S99
EXC
SYNREF
SYNCHRONOUS
REFERENCE
LOS
TO
TRANSDUCER
PUSH/
PULL
O/P STAGE
EXC
PRODUCT HIGHLIGHTS
Dynamic Phase Compensation
The AD2S99 dynamically compensates for any phase variation
in a transducer by phase locking its synchronous reference out-
put to the transducer’s secondary windings.
Programmable Excitation Frequency
The excitation frequency is easily programmed to 2 kHz, 5 kHz,
10 kHz, or 20 kHz by using the frequency select pins. Interme-
diate frequencies are available by adding an external resistor.
Signal Loss Detection
The AD2S99 has the ability to detect if both the transducer sec-
ondary winding connections become disconnected from its SIN
and COS inputs. The “LOS” output pin pulls high when a sig-
nal loss is detected.
Integration
The AD2S99 integrates the transducer excitation, synchronous
reference, and loss of signal detection functions into a small,
cost effective package.
GENERAL DESCRIPTION
The AD2S99 programmable sinusoidal oscillator provides sine
wave excitation for resolvers and a wide variety of ac transduc-
ers. The AD2S99 also provides a synchronous reference output
signal (3 V p-p square wave) that is phase locked to its SIN and
COS inputs. In an application, the SIN and COS inputs are
connected to the transducer’s secondary windings.
The synchronous reference output compensates for temperature
and cabling dependent phase shifts and eliminates the need for
external preset phase compensation circuits. The synchronous
reference output can be used as a zero crossing reference for
resolver-to-digital converters such as Analog Devices’ AD2S80A,
AD2S82A, AD2S83 and AD2S90.
The AD2S99 is packaged in a 20-pin PLCC and operates over
–40°C to +85°C.
FEATURES
Programmable Sinusoidal Oscillator
Synthesized Synchronous Reference Output
Programmable Output Frequency Range: 2 kHz–20 kHz
“Loss-of-Signal” Indicator
20-Pin PLCC Package
Low Cost
APPLICATIONS
Excitation Source for:
Resolvers
Synchros
LVDTs
RVDTs
Pressure Transducers
Load Cells
AC Bridges
© Analog Devices, Inc., 1995
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
AD2S99
