Description

Based on the single-channel ADS1271, the ADS1274 (quad) and ADS1278 (octal) are 24-bit, delta-sigma (ΔΣ) analog-to-digital converters (ADCs) with data rates up to 144k samples per second (SPS), allowing simultaneous sampling of four or eight channels. The devices are offered in identical packages, permitting drop-in expandability.

Traditionally, industrial delta-sigma ADCs offering good drift performance use digital filters with large passband droop. As a result, they have limited signal bandwidth and are mostly suited for dc measurements. High-resolution ADCs in audio applications offer larger usable bandwidths, but the offset and drift specifications are significantly weaker than respective industrial counterparts. The ADS1274 and ADS1278 combine these types of converters, allowing high-precision industrial measurement with excellent dc and ac specifications.

The high-order, chopper-stabilized modulator achieves very low drift with low in-band noise. The onboard decimation filter suppresses modulator and signal out-of-band noise. These ADCs provide a usable signal bandwidth up to 90% of the Nyquist rate with less than 0.005dB of ripple.

Four operating modes allow for optimization of speed, resolution, and power. All operations are controlled directly by pins; there are no registers to program. The devices are fully specified over the extended industrial range (–40°C to +105°C) and are available in an HTQFP-64 PowerPAD™ package.

Features

• Simultaneously Measure Four/Eight Channels
• Up to 144kSPS Data Rate
• AC Performance:
• 70kHz Bandwidth
• 111dB SNR (High-Resolution Mode)
• –108dB THD
• DC Accuracy:
• 0.8µV/°C Offset Drift
• 1.3ppm/°C Gain Drift
• Selectable Operating Modes:
• High-Speed: 144kSPS, 106dB SNR
• High-Resolution: 52kSPS, 111dB SNR
• Low-Power: 52kSPS, 31mW/ch
• Low-Speed: 10kSPS, 7mW/ch
• Linear Phase Digital Filter
• SPI™ or Frame-Sync Serial Interface
• Low Sampling Aperture Error
• Modulator Output Option (digital filter bypass)
• Analog Supply: 5V
• Digital Core: 1.8V
• I/O Supply: 1.8V to 3.3V

Applications

• Vibration/Modal Analysis
• Multi-Channel Data Acquisition
• Acoustics/Dynamic Strain Gauges
• Pressure Sensors