GENERAL DESCRIPTION
The AD7798/AD7799 is a low power, low noise, complete analog front end 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 30 nV for the AD7799 and 40 nV for the AD7798 when the update rate equals 4.17 Hz.

FEATURES
RMS noise: 80 nV at 16.6 Hz (AD7798)
           65 nV at 16.6 Hz (AD7799)
           30 nV at 4.17 Hz (AD7799)
Current: 400 µA typ
Power-down: 1 µA max
Low noise programmable gain instrumentation-amp
Update rate: 4.17 Hz to 500 Hz
3 differential inputs
Internal clock oscillator
Simultaneous 50 Hz/60 Hz rejection
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
Pressure measurement
Weigh scales
Strain gauge transducers
Gas analysis
Industrial process control
Instrumentation
Portable instrumentation
Blood analysis
Smart transmitters
Liquid/gas chromotography
6-digit DVM