AD2S44:  Low Cost, 14-Bit, Dual Channel Synchro/Resolver-to-Digital Converter

The AD2S44 is a 14-bit dual channel, continuous tracking synchro/ resolver-to-digital converter. It has been designed specifically for applications where space, weight, and cost are at a premium. Each 32-lead hybrid device contains two independent Type II servo loop tracking converters. The ratiometric conversion technique employed provides excellent noise immunity and tolerance of long lead lengths.

The core of each conversion is performed by state-of-the-art mono-lithic, integrated circuits manufactured by the Analog Devices, Inc., proprietary BiMOS II process, which combines the advantages of low power CMOS digital logic with bipolar linear circuits. The use of these ICs keeps the internal component count low and ensures high reliability.

The built-in test (BIT) facility can be used in failsafe systems to provide an indication of whether the converter is tracking accurately.

Each channel incorporates a high accuracy differential condi-tioning circuit for signal inputs providing more than 74 dB of common-mode rejection. Options are available for both synchro and resolver format inputs. The converter output is via a three-state transparent latch allowing data to be read without interruption of the converter operation. The A/B and OE control lines select the channel and present the digital position to the common data outputs.

The AD2S44 also features independent reference inputs where different reference frequencies can be used for each channel.

All components are 100% tested at −55°C, +25°C, and +125°C. Devices are processed to high reliability screening standards and receive further levels of testing and screening to ensure high levels of reliability.