GENERAL DESCRIPTION

The AD7794/AD7795 are low power, low noise, complete analog front ends for high precision measurement applications. They contain a low noise, 24-/16-bit ∑-Δ ADC with six differential inputs. The on-chip low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC.

FEATURES

Up to 23 effective bits

RMS noise: 40 nV @ 4.17 Hz, 85 nV @ 16.7 Hz

Current: 400 μA typical

Power-down: 1 μA maximum

Low noise, programmable gain, instrumentation amp

Band gap reference with 4 ppm/°C drift typical

Update rate: 4.17 Hz to 470 Hz

Six differential analog inputs

Internal clock oscillator

Simultaneous 50 Hz/60 Hz rejection

Reference detect

Programmable current sources

On-chip bias voltage generator

Burnout currents

Low-side power switch

Power supply: 2.7 V to 5.25 V

Temperature range:

B grade: –40°C to +105°C

C grade: –40°C to +125°C

Independent interface power supply

24-lead TSSOP

3-wire serial interface

SPI®, QSPI™, MICROWIRE™, and DSP compatible

Schmitt trigger on SCLK

APPLICATIONS

Temperature measurement

Pressure measurement

Weigh scales

Strain gage transducers

Gas analysis