GENERAL DESCRIPTION

The AD7195 is a low noise, complete analog front end for high precision measurement applications. It contains a low noise, 24-bit sigma-delta (Σ-Δ) analog-to-digital converter (ADC). The on-chip low noise gain stage means that signals of small amplitude can be interfaced directly to the ADC. The AD7195 contains ac excitation, which is used to remove dc-induced offsets from bridge sensors.

FEATURES

AC or DC sensor excitation

RMS noise: 8.5 nV at 4.7 Hz (gain = 128)

16 noise-free bits at 2.4 kHz (gain = 128)

Up to 22.5 noise-free bits (gain = 1)

Offset drift: 5 nV/°C

Gain drift: 1 ppm/°C

Specified drift over time

2 differential/4 pseudo differential input channels

Automatic channel sequencer

Programmable gain (1 to 128)

Output data rate: 4.7 Hz to 4.8 kHz

Internal or external clock

Simultaneous 50 Hz/60 Hz rejection

Power supply

AVDD: 4.75 V to 5.25 V

DVDD: 2.7 V to 5.25 V

Current: 6 mA

Temperature range: –40°C to +105°C

Package: 32-lead LFCSP

INTERFACE

3-wire serial

SPI, QSPI™, MICROWIRE™, and DSP compatible

Schmitt trigger on SCLK

APPLICATIONS

Weigh scales

Strain gage transducers

Pressure measurement

Temperature measurement

Chromatography

PLC/DCS analog input modules

Data acquisition

Medical and scientific instrumentation