ADS124x Analog-to-Digital Converters

By Texas Instruments 88

ADS124x Analog-to-Digital Converters

Texas Instruments' ADS1246, ADS1247, and ADS1248 are highly-integrated, precision, 24-bit ADCs. The devices feature an onboard, low-noise, PGA, a precision delta-sigma (ΔΣ) ADC with a single-cycle settling digital filter, and an internal oscillator. The ADS1247 and ADS1248 also provide a built-in, very low drift voltage reference with 10 mA output capacity and two matched programmable current digital-to-analog converters (DACs). The devices provide a complete front-end solution for temperature sensor applications including thermal couples, thermistors, and resistance temperature detectors (RTDs).

An input multiplexer supports four differential inputs for the ADS1248, two for the ADS1247, and one for the ADS1246. In addition, the multiplexer has a sensor burn-out detect, voltage bias for thermocouples, system monitoring, and general-purpose digital I/Os (ADS1247 and ADS1248). The onboard, low-noise PGA provides selectable gains of 1 to 128. The ΔΣ modulator and adjustable digital filter settle in only one cycle for fast channel cycling when using the input multiplexer, and support data rates up to 2 kSPS. For data rates of 20 SPS or less, both 50 Hz and 60 Hz interference are rejected by the filter.

Features
  • 24-bits, no missing codes
  • Programmable data rates up to 2 kSPS
  • Single-cycle settling for all data rates
  • Simultaneous 50 Hz and 60 Hz rejection at 20 SPS
  • Analog multiplexer with eight (ADS1248) and four (ADS1247) independently selectable inputs
  • Low-noise PGA: 48 nVRMS at PGA = 128
  • Dual-matched programmable excitation current sources
  • Low-drift internal 2.048 V reference: 10 ppm/°C (max)
  • Sensor burn-out detection
  • Four or eight general-purpose I/Os (ADS1247, ADS1248)
  • Internal temperature sensor
  • Power supply and VREF monitoring (ADS1247, ADS1248)
  • Self and system calibration
  • SPI-compatible
  • Analog supply: unipolar (2.7 V to 5.25 V) and bipolar (±2.5 V) operation
  • Digital supply: 2.7 V to 5.25 V
  • Operating temperature: -40°C to +125°C
Applications
  • Temperature sensor measurements:
    • RTDs, thermocouples, and thermistors
  • Pressure measurements
  • Flow meters
  • Factory automation and process controls

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