GENERAL DESCRIPTION

The AD7708/AD7718 are complete analog front-ends for low frequency measurement applications. The AD7718 contains a 24-bit Σ-∆ ADC with PGA and can be configured as 4/5 fully-differential input channels or 8/10 pseudo-differential input channels. Two pins on the device are configurable as analog inputs or reference inputs. The AD7708 is a 16-bit version of the AD7718. Input signal ranges from 20 mV to 2.56 V can be directly converted using these ADCs. Signals can be converted directly from a transducer without the need for signal conditioning.

FEATURES

8-/10-Channel, High Resolution Σ-∆ ADCs

AD7708 Has 16-Bit Resolution

AD7718 Has 24-Bit Resolution

Factory-Calibrated

Single Conversion Cycle Setting

Programmable Gain Front End

Simultaneous 50 Hz and 60 Hz Rejection

VREF Select™ Allows Absolute and Ratiometric

Measurement Capability

Operation Can Be Optimized for

Analog Performance (CHOP = 0) or

Channel Throughput (CHOP = 1)

INTERFACE

3-Wire Serial

SPITM, QSPITM, MICROWIRETM, and DSP-Compatible

Schmitt Trigger on SCLK

POWER

Specified for Single 3 V and 5 V Operation

Normal: 1.28 mA Typ @ 3 V

Power-Down: 30 μA (32 kHz Crystal Running)

On-Chip Functions

Rail-to-Rail Input Buffer and PGA

2-Bit Digital I/O Port

APPLICATIONS

Industrial Process Control

Instrumentation

Pressure Transducers

Portable Instrumentation

Smart Transmitters