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.