Mixed Signal/Analog

High accuracy SAR ADCs simplify high-voltage designs

9th October 2014
Nat Bowers

Texas Instruments has introduced the first devices in a high-voltage family of SAR ADCs. Claimed to provide the industry’s lowest gain drift, offset voltage and offset drift, the eight-channel ADS8688 and four-channel ADS8684 allow an input of up to ±10.24V from a single 5V supply, significantly simplifying system power requirements.

Also claimed by TI to provide the industry’s highest precision reference, the SAR ADCs enable engineers to achieve unprecedented levels of accuracy for their designs. The ADS8688 and ADS8684 improve total system accuracy in multi-channel industrial applications such as power automation, low- and medium-voltage relay protection, protection relay monitoring, factory automation equipment and PLCs.

The ADCs can achieve accuracy of greater than 99.9% without calibration with DC error specifications that boost system-level performance. Specified gain drift of 4ppm/°C and offset drift of 3ppm/°C eliminate the need for designers to spend time calibrating their systems over temperature ranges. Low-temperature drift specifications are improved by the integrated precision reference and reference buffer, facilitating precision performance over an extended industrial temperature range from -40°C to +125°C, without the need for external circuitry.

Integrating 20 active devices into one chip, including PGAs, driver amplifiers, multiplexer and voltage reference, the SAR ADCs can connect directly to various sensor types that require no signal conditioning.

Texas Instruments also offers a performance demonstration kit (PDK) so that system designers can quickly evaluate the ADS8688 and ADS8684. Including an EVM and simple capture card for plug-and-play functionality, the PDK's GUI enables designers to quickly evaluate ADC performance in specific end equipment.

Supplied in a 38-pin 9.7x4.4mm TSSOP, the ADS8688 and ADS8684 16-bit SAR ADCs are available now for $11.00 and $8.00, respectively. 12- and 14-bit versions will be available in 2015.

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