ADS1257 24-Bit Industrial ADC

Texas Instruments' ADS1257 is a low-noise, 30 kSPS, 24-bit, delta-sigma (ΔΣ) analog-to-digital converter (ADC) with an integrated multiplexer, input buffer, and programmable gain amplifier (PGA). This is in a small 20-pin, 5 mm × 5 mm VQFN package. The combination of integration, high conversion rate, and 24-bit resolution together in a small package makes the device ideally suited for space-constrained applications.

The input multiplexer accepts either two differential or three single-ended input measurements. The sensor break circuit verifies the input connection continuity to the ADC. The selectable input buffer greatly increases the input impedance and, in many cases, eliminates the need for external buffers. The buffer input voltage range includes AGND. The low-noise PGA provides gains from 1 to 64 to accommodate a wide range of inputs (from ±78 mV to ±5 V). The programmable digital filter optimizes ADC resolution (up to 23 bits noise-free) and conversion rates (up to 30 kSPS). The digital filter provides single-cycle settled conversions, and rejection of 50 Hz and 60 Hz interference signals.

The SPI-compatible serial interface operates with as little as three wires, simplifying connections to external controllers. Integrated calibration features support both self and system correction of offset and gain errors for all PGA gain settings. Two bidirectional digital I/Os pins control external circuits.