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