12-Bit RDC
with Reference Oscillator
AD2S1205
Rev. A
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FEATURES
Complete monolithic resolver-to-digital converter (RDC)
Parallel and serial 12-bit data ports
System fault detection
±11 arc minutes of accuracy
Input signal range: 3.15 V p-p ± 27%
Absolute position and velocity outputs
1250 rps maximum tracking rate, 12-bit resolution
Incremental encoder emulation (1024 pulses/rev)
Programmable sinusoidal oscillator on board
Single-supply operation (5.00 V ± 5%)
−40°C to +125°C temperature rating
44-lead LQFP
4 kV ESD protection
Qualified for automotive applications
APPLICATIONS
Automotive motion sensing and control
Hybrid-electric vehicles
Electric power steering
Integrated starter generator/alternator
Industrial motor control
Process control
FUNCTIONAL BLOCK DIAGRAM
06339-001
REFERENCE
OSCILLATOR
(DAC)
TYPE II TRACKING LOOP
FAULT
DETECTION
POSITION REGISTER
RESET
AD2S1205
DATA BUS OUTPUT
VELOCITY REGISTER
ENCODER
EMULATION
SYNTHETIC
REFERENCE
INTERNAL
CLOCK
GENERATOR
VOLTAGE
REFERENCE
REFERENCE
PINS
CR
ST
L
DATA I/O
ADC
ADC
MULTIPLEXER
EXCITATION
OUTPUTS
INPUTS
FROM
RESOLVER
FAULT
DETECTION
OUTPUTS
ENCODER
EMULATION
OUTPUTS
Figure 1.
GENERAL DESCRIPTION
The AD2S1205 is a complete 12-bit resolution tracking
resolver-to-digital converter that contains an on-board
programmable sinusoidal oscillator providing sine wave
excitation for resolvers.
The converter accepts 3.15 V p-p ± 27% input signals on the Sin
and Cos inputs. A Type II tracking loop is employed to track the
inputs and convert the input Sin and Cos information into a digital
representation of the input angle and velocity. The maximum
tracking rate is a function of the external clock frequency. The
performance of the AD2S105 is specified across a frequency
range of 8.192 MHz ± 25%, allowing a maximum tracking rate
of 1250 rps.
PRODUCT HIGHLIGHTS
1. Ratiometric Tracking Conversion. The Type II tracking
loop provides continuous output position data without
conversion delay. It also provides noise immunity and
tolerance of harmonic distortion on the reference and
input signals.
2. System Fault Detection. A fault detection circuit can sense
loss of resolver signals, out-of-range input signals, input
signal mismatch, or loss of position tracking.
3. Input Signal Range. The Sin and Cos inputs can accept
differential input voltages of 3.15 V p-p ± 27%.
4. Programmable Excitation Frequency. Excitation frequency
is easily programmable to 10 kHz, 12 kHz, 15 kHz, or 20 kHz
by using the frequency select pins (the FS1 and FS2 pins).
5. Triple Format Position Data. Absolute 12-bit angular position
data is accessed via either a 12-bit parallel port or a 3-wire
serial interface. Incremental encoder emulation is in standard
A-quad-B format with direction output available.
6. Digital Velocity Output. 12-bit signed digital velocity accessed
via either a 12-bit parallel port or a 3-wire serial interface.
