24-Bit, 156 kSPS, 112 dB Sigma-Delta ADC with On-Chip Buffers and Serial Interface
Using the AD7765 eases the front-end antialias filtering requirements, simplifying the design process significantly. The AD7765 offers pin-selectable decimation rates of 128× and 256×. Other features include an integrated buffer to drive the reference, as well as a fully differential amplifier to buffer and level shift the input to the modulator.
An overrange alert pin indicates when an input signal has exceeded the acceptable range. The addition of internal gain and internal overrange registers makes the AD7765 a compact, highly integrated data acquisition device requiring minimal peripheral components.
The AD7765 also offers a low power mode, significantly reducing power dissipation without reducing the output data rate or available input bandwidth.
The differential input is sampled at up to 40 MSPS by an analog modulator. The modulator output is processed by a series of low-pass filters. The external clock frequency applied to the AD7765 determines the sample rate, filter corner frequencies, and output word rate.
The AD7765 device boasts a full band on-board FIR filter. The full stop-band attenuation of the filter is achieved at the Nyquist frequency. This feature offers increased protection from signals that lie above the Nyquist frequency being aliased back into the input signal bandwidth.
The reference voltage supplied to the AD7765 determines the input range. With a 4 V reference, the analog input range is ±3.2768 V differential, biased around a common mode of 2.048 V. This common-mode biasing can be achieved using the on-chip differential amplifier, further reducing the external signal conditioning requirements.
The AD7765 is available in a 28-lead TSSOP package and is specified over the industrial temperature range of −40°C to +85°C.
- Data acquisition systems
- Vibration analysis
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
The EVAL-AD7764EDZ / EVAL-AD7765EDZ are fully featured evaluation kits for the AD7764 / AD7765. These boards operate in stand alone mode or in conjunction with the Converter Evaluation and Development board, EVAL-CED1Z . When operated with the Converter Evaluation and Development board, software is provided enabling the user to perform detailed analysis of the ADC's performance. This software includes the technical note describing the operation and set up of the evaluation boards in standalone operation or when operated with the Converter Evaluation and Development board.
MS-2210: Designing Power Supplies for High Speed ADC
Vibration Analysis Using ADCs Keeps Industrial Equipment Working
By Michael Clifford, Analog Devices, Inc. (ECN, 4/2010)
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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