AD7719BR-REEL
AD7719BR-REEL - 16/24-Bit Dual Sigma-Delta ADC AFE | Analog Devices
The Analog Devices AD7719BR-REEL is a complete low-frequency analog front-end integrating two independent high-resolution Sigma-Delta analog-to-digital converters (one 24-bit main channel, one 16-bit auxiliary channel) with switchable matched excitation current sources, low-side power switches, a digital I/O port and an on-chip temperature sensor, packaged in a 28-pin SOIC (300 mil body, 0.295" / 7.50 mm width). It is factory-calibrated so no field calibration is required, accepts fully differential, unipolar or bipolar input ranges from ±REFIN1/128 up to ±REFIN1 through the programmable gain front end, and outputs settle in a single conversion cycle in single-conversion mode. The serial interface is SPI/QSPI/MICROWIRE/DSP-compatible, supporting simultaneous sampling and conversion of two signal sources with separate reference inputs per channel and simultaneous 50 Hz and 60 Hz mains rejection at a 20 Hz update rate.
A Sigma-Delta ADC (also written as Sigma-Delta or SD ADC) is a class of oversampling noise-shaping converter that uses high clock rates and digital filtering to achieve very high effective resolution in low-bandwidth measurement applications such as strain gauges, RTDs, thermocouples and industrial process signals. Within the broader signal-chain taxonomy, the AD7719 sits at the analog front-end (AFE) layer above the raw ADC cell: it bundles gain, excitation, reference input, switching and serialization so that a microcontroller or DSP can read a digitized, calibrated, temperature-compensated signal directly from the bridge.
Key features include 2 independent ADCs (24-bit main + 16-bit auxiliary), factory calibration, programmable-gain front end (gains of 1, 2, 4, 8, 16, 32, 64, 128), 20 mA matched excitation current sources with ISOURCE Select switching, on-chip temperature sensor, simultaneous 50 Hz / 60 Hz rejection, and a 28-pin SOIC footprint that drops into the same SOIC-28 socket as the AD7708, AD7714 and AD7799 family devices. The AD7719BR-REEL is supplied on a 13" tape-and-reel (TR) format suitable for high-volume SMT assembly.
Architecturally, the main 24-bit channel uses a switched-capacitor Sigma-Delta modulator followed by a digital sinc filter; gain and offset coefficients are stored on-chip after factory trim. Two separate REFIN pins allow ratiometric bridges on the 24-bit channel and a separate reference on the 16-bit channel without interaction. Low-side power switches on the excitation pair simplify 4-wire sensor switching without external MOSFETs. Typical input ranges are ±20 mV to ±2.56 V at the 24-bit channel and 0 to VREF at the 16-bit channel.
Typical applications include weigh scales, pressure transmitters, RTD / thermocouple temperature measurement, portable instrumentation and 4-20 mA smart transmitters where the auxiliary 16-bit ADC reads the loop current or supply voltage while the main 24-bit ADC digitizes the bridge output. Designers choose it for its low channel cost (one IC replaces analog signal chain plus two ADCs plus a current source IC) and its factory calibration.
When designing with the AD7719, always provide 0.1 uF + 10 uF decoupling on AVDD/DVDD, route REFIN1 and REFIN2 as Kelvin connections to the bridge / reference, and respect the maximum AVDD-DVDD supply sequencing constraint. The digital I/O port can be configured as inputs, outputs or interrupts; programming uses the SPI-compatible serial interface with the MODE pin selecting the active register map.
This page synthesizes distributor pricing, drop-in 28-SOIC alternatives and practical layout notes not collected in the manufacturer datasheet, providing an AFE-specific decision framework for sensor-front-end designers.
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