TI Surpasses Industry with First Monolithic 18-bit, 500kSPS SAR ADC

6/28/2002 - Texas Instruments (TI) Incorporated (NYSE: TXN) today introduced the industry´s first monolithic 18-bit, 500kSPS successive approximation register (SAR) analog-to-digital converter (ADC). Featuring 18 bits of no missing code performance, the device surpasses the industry standard for high-resolution SAR converters, the most popular ADC architecture.

The new ADS8381 allows high-end instrumentation and medical equipment, chromatography, advanced IC test equipment, optical power monitoring, and wide dynamic range data acquisition systems to achieve a higher level of performance and complexity at a lower cost.

"Historically, SAR and Delta-Sigma converters have provided the necessary dynamic range and linearity for data acquisition and medical equipment. Higher speed may be achieved by a hybrid solution. However, emerging high-end applications can not afford the latency, limited resolution or the price tag associated with these devices," said Tony Chang, strategic marketing engineer for TI's data acquisition products. "In response to this market demand, TI has developed a new performance point for SAR converters. The ADS8381 will allow customers to develop advanced systems with breakthrough resolution, performance and price."

For example, advanced medical X-ray equipment distinguishes layered tissues in complicated human organs for localized detection and intervention procedures. These high-end applications require the reading of receptors to precisely measure a wide range of attenuation along the path of a particular ray in the patient. Previous SAR converters, with their low latency and moderate speed, targeted these requirements but their linearity performance was limited to 16-bit resolution for monolithic implementation. In addition, next-generation medical systems incorporate thousands of channels that demand lower cost and more compact data conversion techniques.

The ADS8381's 18-bit no missing code performance improves image resolution, while the high dynamic range improves the overall efficiency of the data acquisition system. In addition, the converter has incorporated a high-performance on-chip reference buffer. This increased functionality reduces the need for external components, thereby reducing system complexity, circuitry area and total system cost while achieving higher performance.

The ADS8381's nonlinearity is less than +/-9.5 PPM over the first octal input range (+/-2.5 LSB at the 18-bit level). Low power consumption (100mW) is maintained at the 500kHz sampling rate. The device offers a full 18-bit interface, a 16-bit option where data is read using two read cycles, or an 8-bit bus using three read cycles. The ADS8381 operates on a single +5V supply and is specified over the industrial temperature range of -40C to +85C.

Packaging, Price and Availability
The ADS8381 is sampling now, with production scheduled for 3Q02. The device comes in a thin 48-pin TQFP package and will be priced at $19.99 in 1,000 piece quantities (suggested resale pricing).

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