The AD7715 is a complete analog front end for low frequency measurement applications. The part can accept low level input signals directly from a transducer and outputs a serial digital
word. It employs a sigma-delta conversion technique to realize
up to 16 bits of no missing codes performance. The input signal
is applied to a proprietary programmable 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 output update rate.
The AD7715 features a differential analog input as well as a differential
reference input. It operates from a single supply (+3ê V
or +5ê V). It can handle unipolar input signal ranges of 0 mV to
+20ê mV, 0 mV to +80ê mV, 0 V to +1.25ê V and 0 V to +2.5ê V.
It can also handle bipolar input signal ranges of ±20ê mV, ±80ê mV,
±1.25ê V and ±2.5ê V. These bipolar ranges are referenced to
the negative input of the differential analog input. The AD7715
thus performs all signal conditioning and conversion for a singlechannel
system.
The AD7715 is ideal for use in smart, microcontroller or DSP
based systems. It features a serial interface that can be configured
for three-wire operation. Gain settings, signal polarity and
update rate selection can be configured in software using the
input serial port. The part contains self-calibration and system
calibration options to eliminate gain and offset errors on the part itself or in the system.