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Electronic Design

Analog Front-End IC Presents Total Motor-Control Solution

High throughput and simultaneous sampling for multi-axis positioning, motion control, and robotics come via the ADS7869 IC, a complete analog front end for motor-control applications. This Texas Instruments device integrates three 12-bit, 1-Msample/s analog-to-digital converters (ADCs), including seven sample-and-hold circuits and 12 fully differential input channels.

"The ADS7869 advances the industry-standard VECANA01 motor-control solution designed by Burr-Brown 10 years ago, with a faster sampling rate, higher integration, and lower cost," says Miroslav Oljaca, strategic TI's marketing manager for motor-control converter products. "This allows customers to simultaneously measure three motor currents and to precisely determine the position of the motor and load."

The IC includes three fully differential inputs for phase-current measurement. Each input is connected to a window comparator and a sign comparator. This corrects for current distortion caused by dead time and provides a user-selectable level of overcurrent protection. For position-sensor analysis, four sign comparators connected to four input channels and two 16-bit up/down counters are incorporated, along with synchronous and asynchronous sampling to enable precision encoder measurement and position control.

Key specs include 12-bit system offset and gain adjustment for every channel, ±1-LSB integral nonlinearity (INL), ±0.65-LSB differential nonlinearity (DNL), and −78-dB distortion (at 10 kHz). The device has a flexible digital interface, two standard parallel port operating modes, a serial peripheral interface, and a specialized serial interface with three data lines (VECANA01 mode). It interfaces with most DSPs or microcontrollers.

Packaged in a TQFP-100, it costs $14.60 in 1000-piece lots.

Texas Instruments

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