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.