24-bit ADC performs synchronised AC/DC signal sampling

17th May 2016
Mick Elliott

The AD7768 24-bit analogue-to-digital converter (ADC) from Analog Devices is now in stock at distributor Mouser Electronics.. The 8-channel, simultaneous sampling ADC features a sigma-delta modulator and digital filter per channel, enabling the device to perform synchronised sampling of both AC and DC signals and allowing it to become a reusable platform for low-power DC and high-performance AC measurement modules.

The AD7768 is equipped with three power modes and up to 256 kSPS ADC output data rate per ADC channel, achieving -120dB total harmonic distortion (THD), 108dB of dynamic range at a maximum input bandwidth of 110.8kHz, and has a combined typical performance of ±2 ppm integral nonlinearity (INL), ±50 μV offset error, and ±30 ppm gain error.

The ADC allows designer engineers to trade off input bandwidth, output data rate, and power dissipation. Using one of the three power modes — fast mode (256kSPS maximum), median mode (128kSPS maximum) and eco mode (32kSPS maximum) — designers can optimise their designs for noise targets and power consumption.

In addition, the ADC offers 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.

For low-bandwidth and low-noise measurements, the device also offers a sinc response through a sinc5 filter. Both the wideband and sinc5 filters can be selected and run on a per-channel basis, and between the filter options, designers can improve the dynamic range by selecting from decimation rates of ×32, ×64, ×128, ×256, ×512, and ×1024, providing optimal noise performance to the required input bandwidth.

The 12 × 12mm ADC operates over the -40 to +105 degrees Celsius industrial temperature range, and is targeted toward a variety of low-power applications, including data acquisition systems, instrumentation and industrial control loops, vibration and asset condition monitoring, 3-phase power quality analysis, and high-precision medical equipment. Additionally, the AD7768 is supported by an evaluation board, which is also available to order through the Mouser Electronics website.

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