GENERAL DESCRIPTION
The AD1555 is a complete sigma-delta modulator, combined with a programmable gain amplifier intended for low frequency,high dynamic range measurement applications. The AD1555 outputs a ones-density bitstream proportional to the analog input. When used in conjunction with the AD1556 digital filter/ decimator, a high performance ADC is realized.
FEATURES
AD1555
Fourth Order Σ-Δ Modulator
Large Dynamic Range
116 dB Min, 120 dB Typical @ 1 ms
117 dB Typical @ 0.5 ms
Low Input Noise: 80 nV rms @ 4 ms with
Gain of 34,128
Low Distortion: –111 dB Max, –120 dB Typical
Low Intermodulation: 122 dB
Sampling Rate at 256 kSPS
Very High Jitter Tolerance
No External Antialias Filter Required
Programmable Gain Front End
Input Range: ±2.25 V
Robust Inputs
Gain Settings: 1, 2.5, 8.5, 34, 128
Common-Mode Rejection (DC to 1 kHz)
93 dB Min, 101 dB Typical @ Gain of 1
77 mW Typical Low Power Dissipation
Standby Modes
AD1556
FIR Digital Filter/Decimator
Serial or Parallel Selection of Configuration
Output Word Rates: 250 SPS to 16 kSPS
6.2 mW Typ Low Power Dissipation
70 mW in Standby Mode
Reference Design and Evaluation Board with
Software Available
APPLICATIONS
Seismic Data Acquisition Systems
Chromatography
Automatic Test Equipment
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