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Analog Devices AD7768

ADI AD7768: 24-bit, 8-Channel Simultaneous-sampling 256 kSPS Σ-Δ ADC

The AD7768/AD7768-4 are 8-channel and 4-channel, simultaneous sampling sigma-delta (Σ-Δ) analog-to-digital converters (ADCs), respectively, with a Σ-Δ modulator and digital filter per channel, enabling synchronized sampling of ac and dc signals. The AD7768/AD7768-4 achieve 108 dB dynamic range at a maximum input bandwidth of 110.8 kHz, combined with typical performance of ±2 ppm INL, ±50 µV offset error, and ±30 ppm gain error. The AD7768/AD7768-4 user can trade off input bandwidth, output data rate, and power dissipation, and select one of three power modes to optimize for noise targets and power consumption. The flexibility of the AD7768/AD7768-4 allows them to become reusable platforms for low power dc and high performance ac measurement modules. 

The AD7768/AD7768-4 have three modes: fast mode (256 kSPS maximum, 110.8 kHz input bandwidth, 51.5 mW per channel), median mode (128 kSPS maximum, 55.4 kHz input bandwidth, 27.5 mW per channel) and eco mode (32 kSPS maximum, 13.8 kHz input bandwidth, 9.375 mW per channel). The AD7768/AD7768-4 offer extensive digital filtering capabilities, such as a wideband, low ±0.005 dB pass-band ripple, antialiasing low-pass filter with sharp roll-off, and 105 dB stop band attenuation at the Nyquist frequency. Frequency domain measurements can use the wideband linear phase filter. This filter has a flat pass band (±0.005 dB ripple) from dc to 102.4 kHz at 256 kSPS, from dc to 51.2 kHz at 128 kSPS, or from dc to 12.8 kHz at 32 kSPS. The AD7768/AD7768-4 also offer sinc response via a sinc5 filter, a low latency path for low bandwidth, and low noise measurements. The wideband and sinc5 filters can be selected and run on a per channel basis.

AD7768 Evaluation Board - EVAL-AD7768

Features and Benefits

  • Precision ac and dc performance
  • 8-/4-channel simultaneous sampling
    • 256 kSPS maximum ADC output data rate per channel
    • 108 dB dynamic range
    • 110.8 kHz maximum input bandwidth (−3 dB bandwidth)
    • −120 dB total harmonic distortion (THD) typical
    • ±2 ppm of full-scale range (FSR) integral nonlinearity (INL), ±50 µV offset error, ±30 ppm gain error
  • Optimized power dissipation vs. noise vs. input bandwidth
  • Selectable power, speed, and input bandwidth (BW) modes
    • Fast: highest speed; 110.8 kHz BW, 51.5 mW per channel
    • Median: half speed, 55.4 kHz BW, 27.5 mW per channel
    • Eco: lowest power, 13.8 kHz BW, 9.375 mW per channel
  • Input BW range: dc to 110.8 kHz
  • Programmable input bandwidth/sampling rates

Applications

  • Data acquisition systems: USB/PXI/Ethernet
  • Instrumentation and industrial control loops
  • Audio test and measurement
  • Vibration and asset condition monitoring
  • 3-phase power quality analysis
  • Sonar
  • High precision medical electroencephalogram (EEG)/electromyography (EMG)/electrocardiogram (ECG)

Block Diagram

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