1 Features

• Power-scalable modes (DR at 500 SPS, gain = 1):

– High-power mode: 134-dB DR, 11.5 mW

– Mid-power mode: 134-dB DR, 8.5 mW

– Low-power mode: 131-dB DR, 6.5 mW

• THD: –120 dB

• CMRR: 125 dB

• Data rate: 125 SPS to 4000 SPS

• PGA gain: 1 to 64

• Power-saving buffer mode

• Sample rate converter

• Linear- and minimum-phase digital filter

• Programmable high-pass filter

• Test input channel

• Offset and gain calibration

• General-purpose I/Os

• Analog power supply: 3.3 V or 5 V

• Single or dual power-supply operation

• Reference option: 5 V, 4.096 V, or 2.5 V

2 Applications

• Energy exploration

• Passive seismic monitoring

• Earth sciences

• Precision instrumentation

3 Description

The ADS1285 is a high-resolution, low-power

consumption, analog-to-digital converter (ADC), with

a programmable gain amplifier (PGA) and a finite

impulse response (FIR) filter. The ADC is suitable for

the demanding needs of seismic equipment requiring

precision digitization with long battery run time.

The ADC features a low-noise PGA (6 nV/√Hz)

suitable for direct connection to geophones and

transformer-coupled hydrophones without the need of

external amplifiers.

Power-scalable modes trade-off dynamic range

against power consumption. Optional buffer operation

bypasses the PGA to further reduce power

consumption.

The ADC incorporates a high-resolution, low-drift,

delta-sigma (ΔΣ) modulator and a FIR digital filter with

programmable phase response. The high-pass filter

(HPF) removes dc and low-frequency content from

the signal. The sample rate converter (SRC) corrects

the effect of clock frequency error to within 7-ppb

resolution.

The ADC is available in a compact 5-mm × 5-mm

VQFN package and is fully specified over the –40°C

to +85°C temperature range.