EVAL-AD7798| Application Note
Evaluation Board for the AD7798 16-Bit, Low Power Sigma-Delta ADC (3 Channels) EVAL-AD7798
FEATURES
Full-featured evaluation board for the AD7798 Standalone USB interface Various linking options PC software for control of AD7798
analog input channel of the AD7798 accepts analog input signals of VREF/gain, with a gain in the range of 1 to 128. When the gain is 64 and the update rate is programmed to 16.7 Hz, the rms noise is 85 nV. Simultaneous 50 Hz/60 Hz rejection is also available at this data update rate. Full data on the AD7798 is available in the AD7798 data sheet, available from Analog Devices, Inc., and should be consulted in conjunction with this document when using the evaluation board. The evaluation board interfaces to the USB port of an IBMcompatible PC. Software is available with the evaluation board that allows the user to easily communicate with the AD7798. The AD7798 evaluation board software should be installed before connecting the AD7798 evaluation board to the PC. Other components on the AD7798 evaluation board include the ADP3303, which is a high precision, low power, 3.3 V output voltage regulator used to power the USB/SPI interface.
GENERAL DESCRIPTION
This data sheet describes the evaluation board for the AD7798 low power, 16-bit - ADC. The AD7798 is a complete analog front end for low frequency measurement applications. It contains three differential inputs and includes a low noise instrumentation amplifier, a reference detect, and a low-side power switch. Features include an update rate that can be varied from 4.17 Hz to 470 Hz, an on-board clock that eliminates the need for an external clock, and a - conversion technique that allows attainment of up to 16 bits of no missing codes performance. The input signal is applied to an analog modulator, and the modulator output is processed by an on-chip digital filter. The
FUNCTIONAL BLOCK DIAGRAM
AVDD TEMPERATURE SENSOR VOLTAGE REGULATOR
ANALOG INPUTS
AD7798
SPI/USB INTERFACE
PC AND LabVIEWTM BASED SOFTWARE
REFIN( )
Figure 1.
Rev. 0
Evaluation boards are only intended for device evaluation and not for production purposes. Evaluation boards are supplied "as is" and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. No license is granted by implication or otherwise under any patents or other intellectual property by application or use of evaluation boards. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Analog Devices reserves the right to change devices or specifications at any time without notice. Trademarks and registered trademarks are the property of their respective owners. Evaluation boards are not authorized to be used in life support devices or systems.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. www.analog.com Tel: 781.329.4700 Fax: 781.461.3113 2008 Analog Devices, Inc. All rights reserved.
07432-001
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