FEATURES

Full-featured evaluation board for the AD7793

Standalone USB interface

Various linking options

PC software for control of AD7793

GENERAL DESCRIPTION

This data sheet describes the evaluation board for the AD7793, which is a low power, 24-bit sigma-delta (Σ-Δ) ADC. The AD7793 is a complete analog front end for low frequency measurement applications. It contains three differential inputs and includes a low noise instrumentation amplifier, an embedded reference, and programmable current sources. The update rate can be varied from 4.17 Hz to 470 Hz. It also has an on-board clock, eliminating the need for an external clock. It employs a Σ-Δ conversion technique to realize up to 24 bits of no missing codes performance. The input signal is applied to an analog modulator. The modulator output is processed by an on-chip digital filter. The analog input channel of the AD7793 accepts analog input signals of ±VREF/gain, with gain equal to 1 to 128.

With a gain of 64 and the update rate programmed to 16.7 Hz, the rms noise is 85 nV. Simultaneous 50 Hz/60 Hz rejection is available at this data update rate also.

Full data on the AD7793 is available in the AD7793 data sheet available from Analog Devices, Inc., and should be consulted in conjunction with this data sheet when using the evaluation board.

The evaluation board interfaces to the USB port of an IBM-compatible PC. Software is available with the evaluation board that allows users to easily communicate with the AD7793.

Note that the AD7793 evaluation board software should be installed before connecting the AD7793 evaluation board to the PC.

Another component on the AD7793 evaluation board is the ADP3303 high precision, low power, 3.3 V output voltage regulator, which is used to power the USB/SPI interface.