GENERAL DESCRIPTION
The AD7709 is a complete analog front-end for low frequency measurement applications. The AD7709 contains a 16-bit sigma delta ADC with PGA and can be configured as 2 fully-differential input channels or 4 pseudo-differential input channels. Inputs signal ranges from 20mV to 2.56V can be directly converted using the AD7709. These signals can be converted directly from a transducer without the need for signal conditioning. Other on-chip features include three software configurable current sources, switchable reference inputs, low side power switches and a 4-bit digital I/O port.

FEATURES
    16-BIT SINGLE CHANNEL SIGMA DELTA-ADC
    Factory Calibrated (field calibration not required)
    Output settles in one conversion cycle (single conver sion mode)
    Programmable Gain Front End
    16-bit No Missing Codes
    13-bit Pk-Pk Resolution @ 20Hz, 20mV Range
    16-bit Pk-PK Resolution @ 20Hz, 2.56V Range
INTERFACE
    Three-Wire Serial
    SPI™, QSPI™, MICROWIRE™ and DSP Compatible
    Schmitt Trigger on SCLK
POWER
    Specified for Single 3V and 5V operation
    Normal : 2mA @ 3V
    Powerdown : 20uA (32kHz Crystal Running)
On-Chip Functions
    Rail-to-Rail Input Buffer and PGA
    Switchable Reference Inputs
    3 Configurable Current Sources
    Low Side Power Swtches
    Digital I/O Port

APPLICATIONS
    Industrial Process Control
    Instrumentation
    Pressure Transducers
    Portable Instrumentation