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SAR ADCs aim to simplify high-voltage designs

Posted: 10 Oct 2014 ?? ?Print Version ?Bookmark and Share

Keywords:Texas Instruments? ADC? PLC? amplifier? multiplexer?

Texas Instruments (TI) extended its successive approximation register (SAR) analogue-to-digital converter (ADC) portfolio with the introduction of the first devices in its high-voltage lineup. According to the company, the eight-channel ADS8688 and four-channel ADS8684 feature the industry's lowest gain drift, offset voltage and offset drift, and the highest precision reference, giving engineers unprecedented levels of accuracy for their designs throughout the full extended industrial temperature range.

The family of ADCs can improve total system accuracy in a range of multi-channel industrial applications such as power automation, low- and medium-voltage relay protection, protection relay monitoring, factory automation equipment and programmable logic controllers (PLCs).

TI said the ADS8688 family will simplify system design by eliminating the need to generate separate high-voltage supplies. The devices support bipolar input ranges up to ±10.24V and unipolar ranges up to ±10.24V with a single 5V supply. In addition, the ADCs achieve better than 99.9 per cent accuracy without calibration with DC error specifications that boost system-level performance. With specified gain drift of 4ppm/C and offset drift of 3ppm/C, the devices eliminate the need for designers to spend time calibrating their systems over temperature ranges.


The devices feature an integrated precision reference and reference buffer that improve low-temperature drift specifications, enabling precision performance without requiring external circuitry across the full extended industrial temperature range of -40°C to 125°C. Each device integrates into one chip 20 active devices, including programmable gain amplifiers (PGAs), driver amplifiers, multiplexer, voltage reference, reference buffer and SAR ADC, plus an auxiliary channel input for interfacing straight to the ADC. This integration allows the ADS8688 and ADS8684 to connect directly to various sensor types that require no signal conditioning, added the company.

System designers can evaluate the ADS8688 and ADS8684 by using a performance demonstration kit (PDK) that features a simple installation process. It includes an evaluation module (EVM) and simple capture card for plug-and-play functionality, replacing online software installations with a simple one-click process.

The ADS8688 family of devices come in a 38-pin, 9.7mm x 4.4mm TSSOP package. The 16bit products are available to today. The ADS8688 costs $11 while the ADS8684 can be had for $8 in 1,000-unit quantities.

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