ADS1284 - Ultra-high-resolution 4kSPS 2-ch ADC w/ PGA and low-power mode for seismic and geospace exploration

The ADS1284 is a high-performance, single-chip, analog-to-digital converter (ADC). Thisdevice includes a low-noise programmable gain amplifier (PGA), delta-sigma (ΔΣ) modulator, anddigital filter. The ADC supports two modes of operation with trade-offs between power andresolution.

The two-channel multiplexer has the inputs for signal measurement and an ADC signal test.A mode is available to short circuit the inputs and test for internal noise. The PGA has the highinput impedance and low noise, which provides for the direct connection of geophone and hydrophonesensors.

The fourth-order, inherently stable modulator provides outstanding noise and linearityperformance. The modulator output is filtered and decimated by the on-chip digital filter to yieldthe ADC conversion result.

The digital filter provides data rates from 250 to 4000 SPS. The high-pass filter (HPF)has a programmable corner frequency. On-chip gain and offset scale registers support systemcalibration.

The synchronization input controls the timing of the ADC conversion. The power-down inputputs the ADC into power-down mode.

The ADS1284 is available in a compact 24-lead, 5-mm × 4-mm VQFN package, and is fullyspecified from –40°C to +85°C, with a maximum operating temperature range of –50°C to+125°C.

• Selectable Operating Modes
• Low-Power Mode
  • 12 mW (PGA = 1, 2, 4 and 8)
  • 127 dB SNR (250 SPS, PGA = 1)
• High-Resolution Mode
  • 18 mW (PGA = 1, 2, 4 and 8)
  • 130 dB SNR (250 SPS, PGA = 1)
• THD: –122 dB
• CMRR: 110 dB
• Two-Channel Multiplexer
• Inherently-Stable Modulator
• Fast Responding Overrange Detector
• Flexible Digital Filter:
  • Sinc + FIR + IIR (Selectable)
  • Linear or Minimum Phase Option
  • Programmable High-Pass Filter
• Offset and Gain Calibration
• SYNC Input
• Analog Supply: 5 V or ±2.5 V
• Digital Supply: 1.8 V to 3.3 V

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