ADS1287 - Low-Power, 1kSPS, 1-Ch Delta-Sigma ADC With PGA for Seismic and Energy Exploration

The ADS1287 device is a low-power, analog-to-digital converter (ADC), with an integratedprogrammable gain amplifier (PGA) and finite-impulse-response (FIR) digital filter. The ADC issuitable for the demanding needs of seismic equipment requiring precision digitizing with low powerconsumption.

The ADC features a programmable-gain, high-impedance complementary metal oxidesemiconductor (CMOS) amplifier, suitable for direct connection of geophone and hydrophone sensorsto the ADC over a wide range of input signals (±2.5 V to ±0.156 V).

The ADC incorporates a fourth-order, inherently stable, delta-sigma (ΔΣ) modulator. Themodulator digital output is filtered and decimated by the internal FIR digital filter to yield theADC conversion result.

The FIR digital filter provides data rates up to 1000 samples per second (SPS). Thehigh-pass filter (HPF) removes DC and low frequency components from the conversion result. On-chipgain and offset scaling registers support system calibration.

Together, the amplifier, modulator, and digital filter dissipate 4.5 mW inhigh-resolution mode (2.4 mW in low-power mode). The ADC is packaged in a compact 5-mm × 4-mm VQFNpackage. The ADC is fully specified over the –40°C to +85°C temperature range.

• Selectable Operating Modes
• High-Resolution Mode:
  • SNR: 113 dB (1000 SPS, Gain = 1)
  • Power: 4.5 mW
• Low-Power Mode:
  • SNR: 110 dB (1000 SPS, Gain = 1)
  • Power: 2.4 mW
• THD: –115 dB
• CMRR: 115 dB
• High-Impedance CMOS PGA
  • Gains 1, 2, 4, 8, and 16
• Data Rates: 62.5 SPS to 1000 SPS
• Flexible Digital Filter:
  • Sinc + FIR + IIR (Selectable)
  • Linear and Minimum Phase Response
  • Programmable High-Pass Filter
• Offset and Gain Calibration
• Synchronization Control
• SPI-Compatible Interface
• Analog Power Supply: 5 V or ±2.5 V
• Digital Power Supply: 2.5 V to 3.3 V

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