Analog Devices: Synchro/Resolver to Digital Converters: Analog to Digital Converters: AD2S90/AD2S99 Evaluation Tools
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Analog to Digital
Converters
A/D Converters
Design
AD2S90/AD2S99 Evaluation Tools
AD2S12
Tools
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Digital Converters
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Converters
General Description
AD2S90
Evaluati
The AD2S90 is a complete 12-bit resolution tracking resolver-to-digital (R/D) converter that provides ±10.6 arc minutes of angular
accuracy in a low cost package. The AD2S90 evaluation board is a compact evaluation board to evaluate the AD2S90 R/D
converter and the AD2S99 excitation oscillator. The AD2S90 Evaluation Board is also designed to interface directly with the
ADSP-2101EZLAB, ADMC201-LAB and ADMC3XX evaluation boards. The AD2S90 Evaluation Board consists of:
Resolve
Convert
Tool
„
„
„
All Product Categories
Amplifiers and
Comparators
Analog to Digital
Converters
Digital to Analog
Converters
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DSP
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MEMS and Sensors
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E
„
Related
AD2S90 resolver-to-digital converter IC
AD2S99 programmable sinusoidal oscillator IC
Some additional external components (buffer amplifier)
25-way D-type connector
Technic
Recomm
Reading
bytes)
Both the AD2S90 and the AD2S99 are available in 20-pin PLCC packages, operate on a ±5V dc ±5% power supply and over 40°C to +85°C. Analog ground and Digital ground are connected together and are both equal to 0V. Care should be taken in
connecting the +5V (VDD) and -5V (VSS) power supplies. Reversal of these power supplies will destroy the AD2S90 and AD2S99
devices.
AD2S90 Resolver To Digital Converter
Applicat
Resour
Selectio
The AD2S90 is a complete 12-bit resolution tracking resolver-to-digital converter. The converter accepts 2V rms ±10% input
signals on the SIN, COS and REF inputs. A Type II servo loop is employed to track the inputs and convert the input SIN and
COS information into a digital representation of the input angle. The bandwidth of the converter is set internally at 1kHz. The
maximum tracking rate is 375 rps at 12-bit resolution. Angular position output information is available in two forms, absolute
serial binary and incremental A quad B. The absolute binary output has 12 bits (1 in 4096) of resolution. The data output pin is
high impedance when Chip Select is logic HI. This allows the connection of multiple converters onto a common bus. Absolute
angular information in serial pure binary form is accessed by Chip Select followed by the application of an external clock (SCLK)
with a maximum rate of 2 MHz.
Product
Solution
More...
The encoder emulation outputs A, B and NM continuously produce signals equivalent to a 1024 line encoder. When decoded this
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12/9/2004
Analog Devices: Synchro/Resolver to Digital Converters: Analog to Digital Converters: AD2S90/AD2S99 Evaluation Tools
Management
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corresponds to 12-bits resolution. Three common north marker pulse widths are selected via a single pin (NMC).
References
RF/IF Components
Switches/Multiplexers
Wireless Products
An analog velocity output signal provides a representation of velocity from a rotating resolver shaft traveling in either a clockwise
or counterclockwise direction.
Refer to the AD2S90 Data sheet for the full technical specifications.
Other Linear
Other
AD2S99 Programmable Oscillator
The AD2S99 provides sine wave excitation for resolvers and a wide range of ac transducers. The AD2S99 also provides a
synchronous reference output signal (3V p-p square wave) that is phase locked to its SIN and COS inputs. The SIN and COS
inputs are connected to the resolver's secondary windings. The synchronous reference output compensate for temperature and
cabling dependent phase shifts and eliminates the need for external preset phase compensation circuits. The synchronous
reference output is used as a zero crossing reference for the AD2S90. The excitation frequency is easily programmed to 2kHz,
5kHz, 10kHz, or 20kHz using the frequency select pins (SEL1, SEL2). This is achieved by setting the jumpers JP2 and JP3 to
the appropriate positions. Intermediate frequencies are achieved by setting jumpers JP2 and JP3 to select the frequency
immediately above the required intermediate frequency and connect the frequency adjust pin FBIAS, using jumper JP1, to Vdd
via a 25k potentiometer, R1.
The AD2S99 has the ability to detect if both the resolver secondary winding connections become disconnected from its SIN and
COS inputs. The "LOS" output pin pulls high when a signal loss is detected.
AD2S90/ AD2S99 Configuration
The schematics for the AD2S90 Evaluation board are included at the end of this document (see Figure 2). The output of the
AD2S99 oscillator consists of two sinusoidal signals, EXC, and EXC/. EXC/ is 180° phase advanced with respect to EXC. It is
usually necessary to increase the output current drive these output signals. To do this an external buffer amplifier (OP279 Railto-Rail Multimedia Op-Amp) is used to provide the additional current drive required, providing a single ended drive to the
resolver. The amplitude modulated SIN and COS output signals from a resolver (inputs to the AD2S90) are connected as
feedback signals to the AD2S99. SINLO and COSLO are connected to AGND at the AD2S90 R/D converter. The maximum
levels of the SIN and COS input signals to the AD2S90 should be 2V rms ±10%. The synthesized reference (SYNREF) output
from the AD2S99 compensates for any primary to secondary phase errors in the resolver. These errors can degrade the
accuracy of the AD2S90. SYNREF is connected to the reference input of the AD2S90. The SYNREF signal is a square wave at
the oscillator frequency of amplitude ±3V p-p and is phase coherent with the SIN and COS inputs.
A coupling capacitor and a resistor to ground, to block out any dc offset in the SYNREF signal, are connected between the
SYNREF output of the AD2S99 and the REF input of the AD2S90. All the analog ground signals should be star connected to the
AD2S90 AGND pin. If shielded twisted pair cables are used for the resolver signals , the shields should also be terminated at the
AD2S90 AGND pin. For more detailed information please refer to the AD2S90 and the AD2S99 data sheets.
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Analog Devices: Synchro/Resolver to Digital Converters: Analog to Digital Converters: AD2S90/AD2S99 Evaluation Tools
Page 3 of 4
Serial Interface
The AD2S90 Evaluation Board is designed to interface directly with the ADSP-2101EZLAB, ADMC201-LAB and ADMC3XX
evaluation boards. The AD2S90 evaluation board interfaces to these evaluation boards by plugging the male 25-way D-type
connector on the AD2S90 evaluation board into the female equivalent on the ADSP-2101EZLAB, ADMC201-LAB and ADMC3XX
evaluation boards, as in the diagram below (Figure 1). The DSP on the ADSP-2101EZLAB, ADMC201-LAB and ADMC3XX
evaluation boards provides a chip select signal, via RFS0, and a serial clock, via SCLK0, to the AD2S90. The chip select is
active low and a logic LO transition enables the DATA output to feed data back to the DSP, via DR0.
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Analog Devices: Synchro/Resolver to Digital Converters: Analog to Digital Converters: AD2S90/AD2S99 Evaluation Tools
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