Analog Devices Inc. AD7794BRUZ-REEL

Overview

AD7794BRUZ-REEL from Analog Devices is a 24-bit, low-noise, low-power Σ-Δ ADC with integrated instrumentation amplifier, internal 1.17 V band gap reference (4 ppm/°C drift), six differential analog inputs, and programmable excitation current sources. It delivers 23 effective bits at 4.17 Hz, 40 nV RMS noise, and operates from 2.7 V to 5.25 V supply across –40°C to +105°C - ideal for high-precision weigh scales and industrial pressure transducers.

For engineers reviewing the AD7794BRUZ-REEL datasheet, AD7794BRUZ-REEL pinout, AD7794BRUZ-REEL application, or AD7794BRUZ-REEL equivalent, key selection criteria include guaranteed 24-bit no-missing-codes performance at ≤242 Hz update rate, simultaneous 50/60 Hz rejection, on-chip bias voltage generator (AVDD/2), low-side power switch (RON ≤ 9 Ω), and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface.

Technical Context

The AD7794BRUZ-REEL implements a chopper-stabilized Σ-Δ modulator with digital filtering supporting output rates from 4.17 Hz to 470 Hz. Its on-chip instrumentation amplifier provides programmable gain (1–128) and supports buffered/unbuffered input modes with defined common-mode voltage constraints (e.g., GND + 300 mV to AVDD − 1.1 V at gain ≥4).

It integrates dual programmable current sources (10/210/1000 μA, ±5% initial tolerance), reference detect circuitry (0.3–0.65 V threshold), burnout currents, and a temperature sensor (±2°C accuracy). The device uses an internal 64 kHz oscillator or accepts external clocking, and features independent AVDD/DVDD supplies for analog/digital domains.

Key Specifications

Pinout & Package

AD7794BRUZ-REEL is housed in a 24-lead TSSOP package (4.4 mm × 7.8 mm, 0.65 mm pitch) with exposed pad for thermal enhancement. Pin 4 is NC; pins 5/6 double as AIN6(±) and general-purpose outputs P1/P2; pins 15/16 serve as AIN5(±) or excitation current outputs IOUT2/IOUT1; pins 13/14 and 17/18 support dual differential reference inputs REFIN1 and REFIN2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-precision sigma-delta ADC applications.

Compared with AD7172-2BRUZ and ADS1248IPWR, AD7794BRUZ-REEL uniquely combines 24-bit precision, on-chip instrumentation amplifier, dual excitation sources, internal reference, and 1 μA power-down - making it the only single-chip solution for battery-operated, high-accuracy bridge sensor systems requiring minimal external components and guaranteed 23 effective bits at 4.17 Hz.

Availability

AD7794BRUZ-REEL is available at Aetrix Electronics and suitable for weigh scales, industrial pressure transmitters, and RTD-based temperature controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7794BRUZ-REEL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7794BRUZ-REEL belongs to Analog Devices' precision Σ-Δ ADC product line, engineered specifically for low-power, high-resolution sensor signal conditioning in harsh industrial environments - emphasizing integration, drift stability, and ease of system-level calibration.

FAQ

What is the maximum guaranteed resolution of AD7794BRUZ-REEL with no missing codes?

The AD7794BRUZ-REEL guarantees 24-bit no-missing-codes performance when operating at output update rates ≤242 Hz with chop mode enabled. At higher rates (up to 470 Hz), resolution degrades to 23 effective bits due to increased quantization noise. This specification is validated across the full –40°C to +105°C temperature range and applies to the AD7794BRUZ-REEL B-grade variant per Rev. D datasheet Table 1.

Does AD7794BRUZ-REEL support external reference inputs, and what voltage range is acceptable?

Yes, AD7794BRUZ-REEL supports two independent differential external reference inputs (REFIN1 and REFIN2), each accepting voltages from 0.1 V to AVDD. The nominal reference voltage is 2.5 V, and absolute pin limits are GND − 0.3 V to AVDD + 0.3 V. Reference detect circuitry asserts NOXREF if either reference falls below 0.3 V, preventing erroneous conversions - a critical safeguard in the AD7794BRUZ-REEL's operation.

How does the low-side power switch (PSW) function in AD7794BRUZ-REEL, and what is its on-resistance?

The PSW pin in AD7794BRUZ-REEL controls an internal NMOS switch connecting the negative side of bridge sensors to ground. It has RON ≤ 9 Ω at AVDD = 3 V and ≤ 7 Ω at AVDD = 5 V. When asserted, it fully powers down bridge elements between conversions - reducing average system current by up to 65% in cyclic measurement systems. This feature is explicitly documented in the AD7794BRUZ-REEL functional block diagram and specifications table on Page 1 of the Rev. D datasheet.

Can AD7794BRUZ-REEL perform simultaneous 50 Hz and 60 Hz rejection, and under what conditions?

Yes, AD7794BRUZ-REEL achieves simultaneous 50 Hz and 60 Hz rejection of ≥80 dB minimum when using its internal 64 kHz clock and programming FS[3:0] = 1010 in the mode register. This capability is inherent to its digital filter architecture and requires no external components. The rejection is specified at 50 ±1 Hz and 60 ±1 Hz, making AD7794BRUZ-REEL suitable for global deployments where mains frequency varies between regions.

What are the valid operating supply voltage ranges for AVDD and DVDD in AD7794BRUZ-REEL?

AD7794BRUZ-REEL operates with AVDD and DVDD independently rated from 2.7 V to 5.25 V. Absolute maximum ratings allow up to +7 V, but functional operation is guaranteed only within the 2.7–5.25 V range. The device supports split-supply configurations (e.g., AVDD = 5 V, DVDD = 3.3 V) and includes independent power supply rejection (100 dB min) - a key specification confirmed in Table 1 of the AD7794BRUZ-REEL Rev. D datasheet.