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AD2S90:  Low Cost, Complete 12-Bit Resolver-to-Digital Converter

Product Details

The AD2S90 is a complete 12-bit resolution tracking resolver-to- digital converter. No external components are required to operate the device.

The converter accepts 2 V rms ± 10% input signals in the range 3 kHz-20 kHz 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 1 kHz. 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 serial binary output is 12-bit (1 in 4096). The data output pin is high impedance when Chip Select CS 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 CS followed by the application of an external clock (SCLK) with a maximum rate of 2 MHz.

The encoder emulation outputs A, B and NM continuously produce signals equivalent to a 1024 line encoder.

When decoded this corresponds to 12-bits resolution. Three common north marker pulse widths are selected via a single pin (NMC).

An analog velocity output signal provides a representation of velocity from a rotating resolver shaft traveling in either a clockwise or counterclockwise direction.

The AD2S90 operates on a ±5 V dc ± 5% power supplies and is fabricated on Analog Devices' Linear Compatible CMOS process (LC2MOS). LC2MOS is a mixed technology process that combines precision bipolar circuits with low power CMOS logic circuits.


  • Complete Monolithic Resolver-to-Digital Converter
  • Incremental Encoder Emulation (1024-Line)
  • Absolute Serial Data (12-Bit)
  • Differential Inputs
  • 12-Bit Resolution
  • Industrial Temperature Range
  • 20-Lead PLCC
  • Low Power (50 mW)

Functional Block Diagram for AD2S90


Title Content Type File Type
AD2S90: Low Cost, Complete 12-Bit Resolver-to-Digital Converter Data Sheet  (Rev D, 01/1999) (pdf, 168 kB) Data Sheets PDF
AN-234: Digital Resolver Integration  (pdf, 133 kB) Application Notes PDF
AN-264: Dynamic Characteristics of Tracking Converter  (pdf, 205 kB) Application Notes PDF
AN-263: Resolver to Digital Conversion; Simple Alternative to Optical Shaft Encoders  (pdf, 520 kB) Application Notes PDF
AN-230: 0: Circuit Applications of the AD2S90 R/D Converter  (pdf, 240 kB) Application Notes PDF
Single Chip DSP Motor Control Systems Catching on in Home Appliances  (pdf, 18 kB)
An article by David Krakauer of Analog Devices, reprinted from the October 2000 issue of Appliance Magazine. This article addresses how Embedded DSP motor control is revolutionizing the appliance industry, not only by delivering the highest levels of motor performance, but also by the method employed to deliver that high performance.
Technical Articles PDF
DSP Motor Control in Domestic Appliance Applications  (pdf, 161 kB)
An article by Dr. Aengus Murray of Analog Devices printed in ECN Magazine, May 2000 issue. The article addresses DSP-based motor control systems offering the control bandwidth required to make possible the development of advanced motor drive systems for domestic appliance applications.
Technical Articles PDF
Motion-Control ChipSets
(Analog Dialogue, Vol. 30, No. 2, 1996)
Analog Dialogue HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD2S90 IIO Resolver-to-Digital Converter Linux Driver Device Drivers HTML

Evaluation Kits & Symbols & Footprints

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

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Price, packaging, availability

AD2S90 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD2S90AP Status: Production 20 ld PLCC 20 Ind Tube, 49 $37.42 $32.09 N  Material Info PCN Purchase
AD2S90APZ Status: Production 20 ld PLCC 20 Ind Tube, 49 $34.08 $29.22 Y  Material Info PCN Purchase
Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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