Analog Devices Inc. AD7709ARU

Description
The AD7709 is a complete analog front end for low-frequency measurement applications. It includes a 16-bit 2-A ADC, selectable reference inputs, three switchable matched excitation current sources, low-side power switches, and a digital I/O port. The 16-bit channel with PGA accepts fully differential, unipolar, and bipolar input signal ranges from 1.024 X REFIN/128 to 1.024 × REFIN. It can be configured as two fully differential input channels or four pseudo-differential input channels. Signals can be converted directly from a transducer without the need for signal conditioning.
The device operates from a 32.768 kHz crystal with an on-chip PLL generating the required internal operating frequency. The output data rate from the part is software programmable. The p-p resolution from the part varies with the programmed gain and output data rate.
The part operates from a single 3 V or 5 V supply. When operating from 3 V supplies, the power dissipation for the part is 3.75 mW. The AD7709 is housed in a 24-lead TSSOP package.

Features
16-Bit Σ-A ADC
Programmable Gain Front End
Simultaneous 50 Hz and 60 Hz Rejection at 20 Hz Update Rate
VREF Select™ Allows Absolute and Ratiometric Measurement Capability
ISOURCE Select™
16-Bit No Missing Codes
13-Bit p-p Resolution @ 20 Hz, 20 mV Range
16-Bit p-p Resolution @ 20 Hz, 2.56 V Range
3-Wire Serial
SPI, QSPI™, MICROWIRE™, and DSP Compatible
Schmitt Trigger on SCLK
Specified for Single 3 V and 5 V Operation
Normal: 1.25 mA Typ @ 3 V
Power-Down: 7 μA (32.768 kHz Crystal Running)
Rail-to-Rail Input Buffer and PGA
Selectable Reference Inputs
3 Switchable, Ratioed Current Sources for VBE Measurements
4-Bit Digital I/O Port
Low-Side Power Switches

Applications
Sensor Measurement
Temperature Measurement
Pressure Measurements
Weigh Scales
Portable Instrumentation
4-20 mA Loops