ADI’s new A/D data converters set speed, accuracy marks

Analog Devices Inc. (ADI) just announced two new data converters that reportedly deliver industry-best speeds and high accuracy at high-bit resolutions.

By Control Engineering Staff July 8, 2004
Typical applications for AD7641 SAR converter (left) include high-speed data acquisition (PC-based systems, SCADA, and DSP interfaces), while AD7760 is suited to vibration analysis, automated test equipment, and medical imaging.

Analog Devices Inc . (ADI) just announced two new data converters that reportedly deliver industry-best speeds and high accuracy at high-bit resolutions. By eliminating the need for complex front-end signal conditioning, these analog-to-digital converters (ADCs) simplify circuit design and decrease system cost, according to ADI. The new converters are: AD7641 , an 18-bit successive-approximation register (SAR) ADC, and AD7760 , a high-speed 20-bit sigma-delta ADC.

“The two converter architectures represent breakthroughs in their own right,” James Caffrey, ADI’s product marketing manager for precision converters, told Control Engineering. “They allow users to maintain signal integrity with less processing and promote a design with fewer components.”

AD7641 SAR converter operates at a sampling rate of 2 MSPS—four times faster than the closest competition, while improving accuracy by a factor of three, says ADI. Typical nonlinearity is 2 LSB (least significant bit) and SNR (signal-to-noise ratio) is 93 dB. Its wider dynamic range eliminates the need for a programmable gain amplifier in many applications. AD7641’s low power consumption (100 mW at 2 MSPS) translates into reduced system cost. Customers can further reduce power dissipation by operating the ADC in “impulse mode,” where power dissipation decreases with throughput. Users can select from fastest throughput to lowest power consumption.

AD7760 sigma-delta converter is said to deliver the industry’s highest SNR of 100 dB at 2.5 MSPS update rate. It also simplifies complex anti-aliasing filtering, which reduces design effort, cost, and time to market. An on-chip buffer and differential amplifier further reduce the need for external components. Caffrey adds that sigma-delta converters, good at digitizing low-value signals, have been slow performers in the past, and therefore were traditionally used for relatively slow signals. “Today, AD7760 sigma-delta pushes the speed boundary.”

Both converters are sampling now with full production expected in October 2004 for AD7641 and February 2005 for AD7760. Pricing in 1,000-piece quantities is $32.95 each for AD7641, available in either a 48-lead LFCSP (lead frame, chip-scale package) or LQFP (low-profile quad flat pack) and $34.95 each for AD7760, which comes in 64-lead TQFP (thin-quad flat pack) or 48-lead LFCSP.

—Frank J. Bartos, executive editor, Control Engineering, fbartos@reedbusiness.com