GENERAL DESCRIPTION
The AD7705/AD7706 are complete analog front ends for low frequency measurement applications. These two-/three-channel devices can accept low level input signals directly from a transducer and produce a serial digital output. They employ a sigma-delta conversion technique to realize up to 16 bits of no missing codes performance. The selected input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an onchip digital filter. The first notch of this digital filter can be programmed via an on-chip control register allowing adjustment of the filter cutoff and output update rate.

FEATURES
   AD7705: Two Fully Differential Input Channel ADCs
   AD7706: Three Pseudo Differential Input Channel ADCs
      16 Bits No Missing Codes
      0.003% Nonlinearity
   Programmable Gain Front End
      Gains from 1 to 128
   Three-Wire Serial Interface
      SPI™, QSPI™, MICROWIRE™ and DSP Compatible
      Schmitt Trigger Input on SCLK
   Ability to Buffer the Analog Input
   2.7 V to 3.3 V or 4.75 V to 5.25 V Operation
   Power Dissipation 1 mW max @ 3␣ V
   Standby Current 8 mA max
   16-Lead DIP, 16-Lead SOIC and TSSOP Packages