The ad7768-1 is a low power, high performance Σ-Δ An analog-to-digital converter (ADC) having a Σ-Δ Modulator and digital filter can realize the accurate conversion of AC and DC signals. The ad7768-1 is a single channel version of the ad7768, which is an 8-channel synchronous sampling Σ-Δ ADC。 Ad7768-1 provides a single configurable and reusable data acquisition (DAQ) package, establishes a new industry standard in the comprehensive performance of AC and DC, and enables instrument and industrial system designers to design across multiple measurement variables for isolated and non isolated applications.

When using low ripple, finite impulse response (FIR) digital filter at 256ksps, ad7768-1 can achieve 108.5db dynamic range, provide 110.8khz input bandwidth (BW), integral nonlinearity (inl) of ± 1.1ppm, offset error of ± 30 µ V and gain error of ± 30ppm.

The sinc5 filter can provide a wide bandwidth of up to 500KHz Nyquist frequency (the − 3dB point of the filter is 204khz), so that the signal can be viewed in an extended range.

Ad7768-1 allows users to flexibly configure and optimize input bandwidth relative to output data rate (ODR) and power consumption. Ad7768-1 is flexible and can dynamically analyze changing input signals, making it especially suitable for general-purpose DAQ systems. Designers can choose one of the three available power modes, so they can achieve the required noise objectives while minimizing power consumption. The design of ad7768-1 is unique. It has become a reusable and flexible platform for low-power DC and High-Performance AC measurement modules.

The ad7768-1 achieves the best balance between DC and AC performance and has excellent power efficiency. The following three operating modes allow the user to make a trade-off between input bandwidth and power budget:

Fast mode can provide a sinc filter with up to 256ksps sampling rate, 52.2khz bandwidth and 26.4mw power consumption, or an FIR filter with up to 256ksps sampling rate, 110.8khz bandwidth and 36.8mw power consumption.

The median mode provides an FIR filter with up to 128ksps sampling rate, 55.4khz bandwidth and 19.7mw power consumption.

Low power mode provides an FIR filter with up to 32ksps sampling rate, 13.85khz bandwidth and 6.75mw power consumption.

High performance Σ-Δ Functional characteristics and application of analog-to-digital converter ad7768-1

Ad7768-1 has a comprehensive digital filtering function, which can meet a variety of system requirements. With these filter options, it is possible to configure frequency domain measurements with tight gain errors over the entire frequency range, linear phase response requirements (brick wall filters), low delay paths (inc5 or sinc3) for control loop applications, and DC input measurements, and to configure sinc3 filters to suppress line frequencies of 50Hz or 60Hz. All filters provide programmable decimation rates.

For users seeking higher ODR than when using low ripple FIR filters, there is a 1.024mhzsinc5 filter path. This path limits quantization noise. Therefore, it is most suitable for customers who need the lowest delay for the control loop or implement custom digital filtering on an external field programmable gate array (FPGA) or digital signal processor (DSP).

Filter options are as follows:

Low ripple FIR filter with ± 0.005db passband ripple (to 102.4khz).

Low delay sinc5 filter with data rate up to 1.024mhz to maximize control loop response performance.

Fully programmable low delay sinc3 filter with 50Hz / 60Hz suppression.

When using ad7768-1, the embedded simulation function in ad7768-1 can greatly reduce the design burden in the whole application range. Compared with competitive products, the precharge buffer on each analog input can reduce the analog input current, thus simplifying the task of external amplifier driving analog input.

The fully buffered input on the reference can reduce the input current and provide a high impedance input to the external reference device, or provide a high impedance input during buffering any reference detection resistor scheme used in proportional measurement.

The device operates with a 5.0vavdd1 − AVSS power supply, a 2.0V to 5.0vavdd2 − AVSS power supply and a 1.8V to 3.3viovdd − DGND power supply.

In low power mode, avdd1, avdd2 and iovdd power supplies can operate with a single 3.3V power rail.

The device requires an external reference. The absolute input reference voltage source (refin) voltage range is 1V to avdd1 − AVSS.

The specified operating temperature range is − 40 ° C to + 125 ° C. The device is packaged in 4mmx5mm28 pin lfcsp.

Please note that in the full text of this data manual, multi-function pins (such as xtal2 / MCLK) can be referred to by the full name of the pin or by a single function of the pin, such as MCLK (when only related to this function).

Application:

Provides a platform ADC with a superset of measurement and sensor types

Sound and vibration, sound wave and material science research and development

Control and hardware cycle verification

Status monitoring for predictive maintenance

Electrical testing and measurement

Audio test and current and voltage measurement

Clinical EEG, EMG and ECG vital signs monitoring

Modular DAQ based on USB, PXI and Ethernet

Channel to channel isolated modular DAQ design

Responsible editor: GT

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