GENERAL DESCRIPTION

The AD7798/AD7799 are low power, low noise, complete analog front ends for high precision measurement applications. The AD7798/AD7799 contains a low noise, 16-/24-bit ∑-∆ ADC with three differential analog inputs. The on-chip, low noise instrumentation amplifier means that signals of small amplitude can be interfaced directly to the ADC. With a gain setting of 64, the rms noise is 27 nV for the AD7799 and 40 nV for the AD7798 when the update rate equals 4.17 Hz.

FEATURES

RMS noise:

27 nV at 4.17 Hz (AD7799)

65 nV at 16.7 Hz (AD7799)

40 nV at 4.17 Hz (AD7798)

85 nV at 16.7 Hz (AD7798)

Current: 380 µA typical

Power-down: 1 µA maximum

Low noise, programmable gain, instrumentation amp

Update rate: 4.17 Hz to 470 Hz

3 differential inputs

Internal clock oscillator

Simultaneous 50 Hz/60 Hz rejection

Reference detect

Low-side power switch

Programmable digital outputs

Burnout currents

Power supply: 2.7 V to 5.25 V

–40°C to +105°C temperature range

Independent interface power supply

16-lead TSSOP package

INTERFACE

3-wire serial

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

Schmitt trigger on SCLK

APPLICATIONS

Weigh scales

Pressure measurement

Strain gauge transducers

Gas analysis

Industrial process control

Instrumentation

Portable instrumentation

Blood analysis

Smart transmitters

Liquid/gas chromotography

6-digit DVM