1 Features
• Selectable resolution-power modes:
– Dynamic range: 134 dB at 2 ms, 11.5 mW
– Dynamic range: 129 dB at 2 ms, 4.8 mW
• Flexible digital filter:
– Selectable sinc + FIR + IIR
– Linear or minimum phase
– High-pass filter
• THD: < –120 dB
• CMRR: 125 dB
• Data rates: 125 SPS to 4000 SPS
• Programmable gains: 1 to 64
• PGA bypass option
• SYNC input
• Clock error compensation
• Two-channel multiplexer
• Offset and gain calibration
• General-purpose digital I/Os
• Analog supply operation: 5 V, 3.3 V, or ±2.5 V
• Reference voltage options: 5 V, 4.096 V, or 2.5 V

2 Applications
• Energy exploration
• Passive seismic monitoring
• Earth sciences and geology
• Precision instrumentation

3 Description
The ADS1285 is a 32-bit, low-power, analog-to-digital
converter (ADC), with a programmable gain amplifier
(PGA) and a finite impulse response (FIR) filter.
The ADC is designed for the demanding needs of
seismology equipment requiring low-noise precision
digitization and extended battery run time.
The low-noise PGA allows direct connection of
geophones and transformer-coupled hydrophones
without the need of an external amplifier.
The ADC incorporates a high-resolution, delta-sigma
(ΔΣ) modulator and a FIR filter with programmable
phase response. The high-pass filter removes dc
and low-frequency content from the signal. Clock
frequency error is compensated by the sample rate
converter with 7-ppb resolution.
Choice of power modes optimize dynamic range
verses power consumption. Power consumption is
further reduced by PGA bypass operation.
The ADC is available in a compact 5-mm × 5-mm
VQFN package and is fully specified over the –40°C
to +85°C ambient temperature range.