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Sigma-delta ADC achieves higher speed and resolution for precision sensing

Norwood, Mass. — Analog Devices, Inc. has unveiled a sigma-delta analog-to-digital converter (ADC) that the company says features the industry's best combination of data rate and noise-free resolution. The 24-bit AD7190 sigma-delta ADC achieves greater than true 16-bit noise-free resolution up to 2.4 kHz across all input voltages from 40 mV to 5 V, enabling industrial equipment manufacturers to expand the operating speed and precision of sensitive measurement instruments.

This level of performance allows designers to measure much smaller signals faster and with greater accuracy, which can significantly improve system performance for precision instruments such as weigh scales, process measurement and control modules, scientific instrumentation and medical monitoring devices, said ADI.

The AD7190 sigma-delta ADC also features an advanced, on-chip programmable gain amplifier (PGA) with ultra-low noise and drift from dc to 4.8 kHz. This enables the sigma-delta ADC to realize an ultra-low noise of only 7 nV rms (root mean squared) at 4.7 Hz data rate with a gain of 128, and an offset drift of only 5 nV/degrees C.

In addition to delivering two bits better resolution than competing sigma-delta ADCs designed to convert small input signals at kHz data rates, the highly integrated AD7190 reduces signal chain cost by up to 25 percent through on-chip features that include an oscillator, temperature sensor, bridge power-down switch, reference detect monitor, and a choice of single-ended, pseudo-differential or fully differential input channels.

Other on-chip features include simultaneous 50-/60-Hz rejection, offset and gain calibration, open sensor detection, a choice of chopped or non-chopped signal, and four general-purpose output pins. A zero-latency mode is selectable in order to reduce software overheads if a valid conversion per data output is desired.

Pricing: The AD7190 (24-lead TSSOP) is priced at $5.90 each in quantities of 1,000.
Availability: Sampling now followed by production quantities in November 2008.
Product information: AD7190, PulSAR ADC evaluation tools, and ADC selection guide
Video: AD7626

Analog Devices Inc. , www.analog.com

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