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Mixed Signal/Analog

4- and 8-Channel Simultaneous Sampling, 24-bit, 128kSPS Industrial ADCs

20th July 2007

ES Admin

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Texas Instruments has introduced a pair of multi-channel, 24-bit industrial analog-to-digital converters which combine outstanding DC accuracy and AC performance with cost-effective integration. The ADS1274 (4-channel) and ADS1278 (8-channel) provide a delta-sigma simultaneous-sampling measurement system for demanding multi-channel signal acquisition applications, such as vibration analysis, medical monitoring, industrial and energy metering equipment.

The ADS1274 and ADS1278 feature 62kHz bandwidth, 0.8uV/C offset drift and up to 111dB signal-to-noise ratio (SNR). Four operating modes allow for optimization of speed (128kSPS data rate), resolution (111dB SNR) and power dissipation (7mW/channel mode). Traditionally, industrial
delta-sigma ADCs offering good drift performance use digital filters with large passband droop, resulting in limited signal bandwidth and 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. The ADS1274 and ADS1278 combine these two types of converters, allowing high-precision industrial measurements with excellent DC and AC specifications.

The high-order, chopper-stabilized modulator achieves very low drift and low noise over the signal bandwidth of DC up to the Nyquist frequency. The onboard decimation filter suppresses modulator and out-of-band noise, providing a usable signal bandwidth up to 90 percent of the Nyquist rate with less than 0.005dB of ripple.

A selectable frame-sync or SPI serial interface provides for convenient interfacing to DSPs, FPGAs and microcontrollers. Either interface supports daisy chaining to simplify readback of multiple ADS1274s or
ADS1278s in high channel count systems. The ADCs are fully specified over the extended industrial range (-40C to +125C for ADS1274 and -40C to +105C for ADS1278).

The ADS1274 and ADS1278 are optimized to work with TI's high-performance TMS320T DSP platforms. TI also has a range of amplifiers, such as the OPA1632 and OPA350, which are well suited to work with these ADCs toachieve highest performance.

The ADS1274 and ADS1278 are available now from TI and its authorized distributors in HTQFP-64 packages. Suggested resale pricing for the ADS1274 starts at $13.95 in 1,000-unit quantities. The ADS1278 starts at $23.95 in 1,000-unit quantities. Evaluation modules are available.