Sigma-Delta A/D Converters feature low noise and low power.

Press Release Summary:

Series AD779x 16- and 24-bit converters, for industrial/medical instrumentation, offer 40 nVrms noise and 400 µA power characteristics. Operating with 2.7-5.25 V power supply, products feature software-programmable output data rate, variable from 4-500 Hz. At 16.6 Hz, they offer simultaneous rejection of 50 Hz and 60 Hz signals. Each product is comprised of sigma-delta A/D converter, instrumentation PGA, multiplexer, current sources, clock, calibration registers, and SPI interface.

Original Press Release:

Analog Devices Delivers Industry's Highest Performance Sigma-Delta ADCs for Industrial and Medical Instrumentation

-New AD779x family of 16- and 24-bit sigma-delta ADCs offer optimal combination of low noise, low power and highly-integrated functionality

NORWOOD, Mass.--Analog Devices, Inc. (NYSE: ADI), a global leader in high-performance semiconductors for signal processing applications and the market leader in data converters, today introduced a new family of sigma-delta analog-to-digital converters (ADCs) that deliver an unprecedented low-noise and low-power solution for applications in industrial and medical instrumentation markets. Unlike traditional precision data-converter solutions, which compromise on either power or noise, the new ADCs feature both low noise (40 nVrms) and low power (400 uA), while offering a complete range of analog functions in less board area. This combination of features is ideal for applications where noise performance is critical, such as industrial process control and weigh scales, and space-constrained, low-power applications, such as portable instrumentation and medical equipment.

"Designers of instrumentation equipment are continually striving to find new ways to simplify their designs, while achieving the optimal balance of low noise and power," said Leo McHugh, marketing manager for precision converters at Analog Devices. "Our new data-converter family solves these design challenges by delivering the best possible performance levels within a highly integrated, yet easy-to-use solution."

Best Balance of Noise and Power in its Class

The AD779x family of analog-to-digital converters, which include the AD7792 (16-bit), AD7793 (24-bit), AD7794 (24-bit), AD7798 (16-bit) and AD7799 (24-bit), outperform comparable solutions--which trade low power for noise or vice versa--by delivering both low noise and low power. Operating with a 2.7-V to 5.25-V power supply, these converters consume only 400 uA. With noise of only 40 nVrms, they enable more accurate measurements in power-sensitive applications. The output data rate from the devices is software programmable and can be varied from 4 Hz to 500 Hz. At 16.6 Hz they offer simultaneous rejection of 50 Hz and 60 Hz signals.

Highly-integrated Solution Eases Instrumentation Design

In addition to these performance advantages, the devices provide all of the functionality required for instrumentation applications, reducing design work and eliminating many external components. The AD779x data-converters include a high performance sigma-delta ADC, low-noise instrumentation programmable gain amplifier (PGA), multiplexer, current sources, clock, calibration registers, SPI interface, and a precision low-noise, low-drift reference (except the AD7798 and AD7799, which use an external reference for ratiometric measurements). Designers have the flexibility to turn off the internal reference, and use an external reference instead.

The PGA, multiplexer, excitation current sources, and input bias voltages allow the AD779x family to connect directly to sensors in myriad applications including PLC/DCS analog I/O measurement; temperature measurement using thermocouples, RTDs or thermistors; weigh scales; pressure and flow measurement; and general-purpose measurement equipment. For pressure and weigh scale applications, a low-side power switch is available to power down the bridge between conversions, minimizing system power consumption; the AD7799 features lower noise (30 nVrms) for these applications.

The AD7794 can accommodate six differential sensor channels, making it ideal for the higher channel requirements of industrial and factory PLC/DCS applications. The other parts in the family can accommodate two or three differential channels.

Pricing and availability

The AD779x family of devices is sampling now and will be available in production quantities in November 2004. The AD7792 (16-bit), AD7793 (24-bit), AD7798 (16-bit) and AD7799 (24-bit) are available in 16-lead TSSOP (thin shrink small outline package), with prices ranging from $3.80 to $5.10 per unit in 1,000 piece quantities. The AD7794 (24-bit) is available in 24-lead TSSOP, and priced at $5.80 per unit in 1,000 piece quantities. For more information, please visit:

About Analog Devices

Analog Devices, Inc. is a leading manufacturer of precision high-performance integrated circuits used in analog and digital signal processing applications. ADI is headquartered in Norwood, Massachusetts, and employs approximately 8,700 people worldwide. It has manufacturing facilities in Massachusetts, California, North Carolina, Ireland, and the Philippines. Analog Devices' common stock is listed on the New York Stock Exchange and ADI is included in the S&P 500 Index.

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