32-bit Δ-Σ ADCs offer high accuracy, low noise and high integration

July 22, 2015 // By Graham Prophet
Texas Instruments has introduced a pair of 32-bit delta-sigma analogue-to-digital converters (ADCs) that combine high resolution, low noise and integrated fault detection, eliminating, claims TI, many of the performance and features trade-offs typically associated with device evaluation and selection.

Suggested uses include programmable logic controllers, industrial automation and sensor measurement: the highly integrated, sensor-ready ADS1262 and ADS1263 also remove the need for external components that increase system cost and degrade noise and drift performance.

TI adds that system designers who needed a high-resolution ADC have had to sacrifice other desired specifications, such as low noise or low offset drift, as well as several integrated features. The ADS1262 and ADS1263 eliminate these trade-offs by providing 32-bit resolution, along with integration, fault-detection features, a fast data rate and wide temperature range, to help maximise the performance of programmable logic controllers (PLCs), industrial automation equipment and sensor-measurement applications.

Accurate measurements of small signals is enabled by resolution of 32 bits and noise of 7 nV RMS at 2.5 SPS, enabling measurement of the smallest signals, which is essential for bridge applications where typical full-scale signals are 10 mV or less. Offset error drift is also 80% lower than alternative solutions, ensuring measurement stability over the entire temperature range.

The ADS1262 integrates a programmable gain amplifier (PGA), 2.5-V reference, oscillator, level shifter, temperature sensor, dual-excitation current sources (IDACs) and eight general-purpose input/output (GPIO) pins. The ADS1263 adds an auxiliary 24-bit delta-sigma ADC for systems needing parallel main-channel conversions, sensor-temperature compensation or sensor diagnostics.

Features such as internal signal-chain monitoring, data-error detection, sensor-burnout detection and a test digital-to-analogue converter (DAC) provide the internal and external fault detection and diagnostics necessary for high-reliability systems, with integrated monitoring. A white paper outlines how to use the ADS1262 and ADS1263’s integrated diagnostics to help improve system reliability.

A maximum output data rate of 38 ksamples/sec enables the ADCs to be used in high-data-throughput industrial applications, and operating temperature range of -40°C to +125C is 20C wider than competing products.

TI has a range of support tools for the ADS1262 and ADS1263, including a TI Designs reference design for high resolution, low drift precision weigh scale measurements using