AD7710

a FEATURES Charge Balancing ADC 24 Bits No Missing Codes ؎ 0.0015% Nonlinearity Two-Channel Programmable Gain Front End Gains from 1 to 128 Differential Inputs Low-Pass Filter with Programmable Filter Cutoffs Ability to Read/Write Calibration Coefficients Bidirectional Microcontroller Serial Interface Internal/External Reference Option Single or Dual Supply Operation Low Power (25 mW typ) with Power-Down Mode (7 mW typ) APPLICATIONS Weigh Scales Thermocouples Process Control Smart Transmitters Chromatography GENERAL DESCRIPTION AVDD AVDD Signal Conditioning ADC AD7710* FUNCTIONAL BLOCK DIAGRAM DVDD REF REF IN (–) IN (+) VBIAS REF OUT 4.5␮A 2.5V REFERENCE CHARGE-BALANCING A/D CONVERTER AIN1(+) AIN1(–) AIN2(+) AIN2(–) AVDD 20␮A IOUT M U X PGA A = 1 – 128 AUTO-ZEROED MODULATOR DIGITAL FILTER SYNC CLOCK GENERATION SERIAL INTERFACE CONTROL REGISTER OUTPUT REGISTER MCLK IN MCLK OUT AD7710 AGND DGND VSS RFS TFS MODE SDATA SCLK DRDY A0 The AD7710 is a complete analog front end for low frequency measurement applications. The device accepts low level signals directly from a strain gage or transducer and outputs a serial digital word. It employs a sigma-delta conversion technique to realize up to 24 bits of no missing codes performance. The input signal is applied to a proprietary programmable gain front end based around an analog modulator. The modulator output is processed by an on-chip digital filter. The first notch of this digital filter can be programmed via the on-c...