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x8 ADCs shrink size, power for portable scanner sockets

Texas Instruments’ analogue- product group has introduced a series of analogue-to-digital converters featuring 10- and 12- bit resolution, with up to 65M-sample/sec sampling speeds, in octal format (eight per package), optimised for small size and low power consumption. TI says you might use them in applications such as medical imaging (ultrasound and MRI), wireless communications, military guidance, automatic test equipment and video. The new part numbers are ADS5281, ADS5282 and ADS5287. At 65 Msps, the ADS5281 family uses 77 mW/channel: with dynamic scaling, at 30 Msps, the per-channel power drops to 48 mW. The chips interface directly to TI’s recently introduced octal variable-gain amplifier, the VCA8500, which exhibits 0.8 nV/√Hz input noise for a 63-mW-per-channel power consumption. The ADC-andoctal- amplifier pairing constitutes a complete medical signal-chain solution with better noise and lower power than alternative offerings, TI claims. Both parts come in 64-pin 9x9-mm QFN packages for high-density systems.

The family of parts features a low-frequency noisesuppression mode that eliminates 1/f (flicker) noise, improving SNR by up to 4.2 dB over a 1-MHz band in baseband and time-domain applications. Overload-recovery circuitry allows each ADC to provide valid data within one clock cycle after an input overload as high as 6 dB, allowing for immediate signal recovery and processing. You can program their gain from 0 to 12 dB, driving full-scale outputs for input signals as low as 0.5 V p-p.

TI also supplies the ADCs in an 80-pin TQFP package that provides an easy transition to these next-generation devices, as it is pin-for-pin compatible with the previousgeneration ADS527x family. 100-piece prices range from $40 to $68.60 depending on speed and resolution. The octal amplifi er costs $40.

Texas Instruments, www.ti.com