GENERAL DESCRIPTION†

The AD7714 is a complete analog front end for low-frequency measurement applications. The device accepts low level signals directly from a 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-chip control register allowing adjustment of the filter cutoff and settling time.

FEATURES

Charge Balancing ADC 24 Bits No Missing Codes 0.0015 Nonlinearity

Five-Channel Programmable Gain Front End Gains from 1 to 128 Can Be Configured as Three Fully Differential Inputs or Five Pseudo-Differential Inputs

Three-Wire Serial Interface SPI™, QSPI™, MICROWIRE™ and DSP Compatible

3 V (AD7714-3) or 5 V (AD7714-5) Operation

Low Noise (<150 nV rms)

Low Current (350␣ mA typ) with Power-Down (5 mA typ)

AD7714Y Grade:

+2.7 V to 3.3 V or +4.75 V to +5.25 V Operation 0.0010 Linearity Error –40°C to +105°C Temperature Range Schmitt Trigger on SCLK and DIN

Low Current (226␣ mA typ) with Power-Down (4 mA typ)

Lower Power Dissipation than Standard AD7714 Available in 24-Lead TSSOP Package

Low-Pass Filter with Programmable Filter Cutoffs

Ability to Read/Write Calibration Coefficients

APPLICATIONS

Portable Industrial Instruments

Portable Weigh Scales

Loop-Powered Systems

Pressure Transducers