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.