Wideband converter

Texas Instruments’ ADS1271 is claimed to be the industry’s widest bandwidth 24-bit industrial analog-to-digital converter (ADC) offering 50kHz bandwidth, 1.8uV/C offset drift and up to 109dB signal-to-noise ratio (SNR).

Traditionally, industrial delta-sigma ADCs offering good drift performance used digital filters with large passband droop, resulting in limited signal bandwidth mostly suited for DC measurements. High-resolution ADCs for audio applications offer larger usable bandwidths, but the offset and drift specifications are significantly worse (and often unspecified) than their industrial counterparts. But TI says that the ADS1271 combines these two converter types, allowing high-precision measurements with excellent DC and AC specifications ensured over a -40C to +105C temperature range.

Utilizing proprietary design techniques, the high-order, chopper-stabilized modulator achieves very low drift (less than 1.8uV/C) with low in-band noise (6.5uV rms). The onboard linear phase decimation filter suppresses modulator and signal out-of-band noise, providing a signal pass-band of 90% of the Nyquist rate with less than 0.005dB of ripple.

Three selectable operating modes allow for optimization of speed (105kSPS data rate), resolution (109dB SNR) and power dissipation (35mW). A selectable frame-sync or SPI serial interface provides for convenient interfacing to DSPs and microcontrollers. All operations, including internal offset calibration, are controlled directly by pins – there are no registers to program.

The ADS1271 is sampling now, with volume production scheduled for 4Q 2004. The device comes in a TSSOP-16 package and is priced at $5.90 in 1,000 piece quantities (suggested resale pricing). Evaluation modules (EVMs) are also available.

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