ADS888x 18-Bit SAR Analog-to-Digital Converters Texas Instruments ADS888x 18-Bit SAR Analog-to-Digital Converters are 18-bit, true-differential input, analog-to-digital converters (ADCs). These devices operate with a 2.5V to 5V external reference, offering a wide selection of signal ranges without additional input signal scaling. The reference voltage setting is independent of, and can exceed, the analog supply voltage (AVDD).