AD7715

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.

CMOS construction ensures very low power dissipation, and the power-down mode reduces the standby power consumption to 50Ê mW typ. The part is available in a 16-lead, 0.3 inch-wide, plastic dual-in-line package (DIP) as well as a 16-lead 0.3 inchwide small outline (SOIC) package and a 16-lead TSSOP package.