Electronic Design

Data-Converter Trio Zeroes In On High-Level Motor Control

Two high-performance data-converter ICs, coupled with a monolithic resolver-to-digital converter (RDC), add advanced motor control to industrial and automotive applications. These Analog Devices chips include the AD7266 analog-to-digital converter (ADC), the AD7400 modulator, and the AD2S1200 RDC.

The dual three-channel AD7266 is a 12-bit, 2-Msample/s, simultaneous-sampling, successive-approximation-register (SAR) ADC. It interfaces with popular optical encoders for shaft-position feedback or with current transformers. It operates from 2.7 to 5.25 V at 20 mW. Shutdown current is 1 µA, and signal-to-noise ratio (SNR) is 70 dB. A 2.5-V reference is on-chip. The 1-Msample/s AD7265 also is available.

The 12-bit second-order sigma-delta modulator AD7400, which includes Analog Devices' iCoupler digital isolation, features a 78-dB SNR over a 20-kHz bandwidth. It also displays 5-µV/8C offset drift, 3.75-kV reinforced isolation, and a 10-MHz data rate (20 MHz for the 7401). Operation is from 5 V at 15 mA, and there's a selectable ±100-mV input (±200 mV for the 7401). The AD7400 includes an internal clock, while the AD7401 requires an external clock.

Highlighted by its 1000-revolution/s tracking and ±11 arc-minute accuracy, the 12-bit AD2S1200 RDC has 12-bit parallel and serial data ports, a reference oscillator, and a 204.8-kHz square-wave output for absolute position and velocity. It offers 5-V differential inputs and allows incremental encoder emulation.

In 1000-piece lots, the AD7265/7266, AD7400/7401, and AD2S1200 cost $5.75/$7.55, $4/$4, and $12 each, respectively. The three units are available in a 32-lead LFCSP or TQFP, 16-lead SOIC, and 44-lead LQFP, respectively.

Analog Devices Inc.

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