AD7713

The AD7713 is a complete analog front end for low frequency measurement applications. The device accepts low level signals directly from a transducer or high level signals (4 × VREF) and outputs a serial digital word. It employs a sigma-delta con- version technique to realize up to 24 bits of no missing codes performance. The input signal is applied to a proprietary pro-grammable gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter.The first notch of this digital filter can be programmed via the on-chip control register allowing adjustment of the filter cutoff and settling time.

The part features two differential analog inputs and one single-ended high level analog input as well as a differential reference input. It can be operated from a single supply (AVDD and DVDD at +5 V). The part provides two current sources which can be used to provide excitation in three-wire and four-wire RTD con-figurations. The AD7713 thus performs all signal conditioning and conversion for a single, dual or three-channel system.

The AD7713 is ideal for use in smart, microcontroller-based systems. Gain settings, signal polarity and RTD current control can be configured in software using the bidirectional serial port. The AD7713 contains self-calibration, system calibration and background calibration options and also allows the user to read and to write the on-chip calibration registers.