The AD7768 is an 8-channel, synchronous sampled Sigma-Delta analog-to-digital converter (ADC) that integrates a sigma-delta modulator and digital filter per channel to support simultaneous sampling of AC and DC signals.
The AD7768 achieves a dynamic range of 108 dB at a maximum input bandwidth of 110.8 kHz and has typical performance of ±2 ppm integral nonlinearity (INL), ± 50 μV offset error, and ± 30 ppm gain error.
AD7768 users can make trade-offs between input bandwidth, output data rate, and power consumption. Choose one of three power modes to optimize noise target and power consumption. The flexibility of the AD7768 makes it a reusable platform for low-power DC and high-performance AC measurement modules.
The AD7768 offers rich digital filtering performance such as wideband, ±0.005 dB low-pass band ripple, anti-aliasing low-pass filter with integrated sharp roll-off performance, and 105 dB attenuation at Nyquist frequency.
Frequency domain measurements can be made using a wideband linear phase filter. The filter has a flat pass band (±0.005 dB ripple) :D C to 102.4 kHz (256 kSPS), DC to 51.2 kHz (128 kSPS), or DC to 12.8 kHz (32 kSPS) in the following ranges. The AD7768 also provides sinc response (via sinc5 filter), low-latency path with low bandwidth, and low-noise measurements. Wideband and sinc5 filters can be selected and run for each channel.
Within these filter options, users can increase dynamic range by selecting from extraction rates ×32, ×64, ×128, ×256, ×512, and ×1024. The ability to change the decimation filter optimizes the noise performance of the required input bandwidth.
Embedded analog functions for each ADC channel simplify the design, such as a precharge buffer on the analog input to reduce the analog input current and a precharge reference buffer for each channel to reduce the input current and glitch at the reference input.
The devices operate from 5 V AVDD1A and AVDD1B supplies, 2.25 V to 5.0 V AVDD2A and AVDD2B supplies, and 2.5 V to 3.3 V or 1.8 V IOVDD supplies (see the "1.8 V IOVDD Power Supply" section for specific supply supply requirements for 1.8 V IOVDD).
For clarity in this document, AVDD1A and AVDD1B power supplies are referred to as AVDD1 and AVDD2A, and AVDD2B power supplies are referred to as AVDD2. For negative supplies, AVSS is used to refer to AVSS1A, AVSS1B, AVSS2A, AVSS2B, and all other AVSS pins.
The devices are rated for a temperature range of −40°C to +105°C and are available in a 12 mm × 12 mm, 64-pin LQFP package.
Throughout the datasheet, multi-function pins (e.g., XTAL2/MCLK) are represented by the entire pin name or the individual function of the pin (e.g., MCLK means that it is only related to this function).
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