Analog Devices Inc. AD7798BRUZ

Overview

AD7798BRUZ from Analog Devices is a 16-bit, low-noise, low-power Σ-Δ analog-to-digital converter with integrated instrumentation amplifier, 3 differential input channels, 4.17–470 Hz programmable update rate, and 40 nV rms noise at 4.17 Hz - designed for high-precision industrial sensor signal conditioning in weigh scales and pressure transducers.

For engineers reviewing the AD7798BRUZ datasheet, AD7798BRUZ pinout, AD7798BRUZ application, or AD7798BRUZ equivalent, this page delivers verified specifications, validated pin functions, confirmed alternative parts with documented technical differences, and real-world use context for sensor front-end design, calibration-critical measurement systems, and low-power embedded instrumentation.

Technical Context

The AD7798BRUZ implements a 3-channel, multiplexed Σ-Δ ADC architecture with on-chip instrumentation amplifier supporting gain settings from 1 to 128. Its internal clock oscillator eliminates external timing components, and simultaneous 50 Hz/60 Hz rejection is achieved via programmable filter settling synchronized to line frequency.

It features independent analog (AVDD) and digital (DVDD) supply rails (2.7–5.25 V each), reference detect circuitry, low-side power switch (PSW), burnout currents, and programmable digital outputs (P1/P2). The device operates across –40°C to +105°C and supports SPI/QSPI/MICROWIRE/DSP-compatible 3-wire serial interface with Schmitt-triggered SCLK.

Key Specifications

Pinout & Package

AD7798BRUZ is housed in a 16-lead TSSOP package (4.4 mm × 5.0 mm, 0.65 mm pitch) with exposed pad for thermal enhancement and standard JEDEC MO-153 compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7798BRUZ, AD7792BRUZ reduces channel count and feature set to lower cost and footprint, while ADS124S08IPWR trades off power efficiency and integrated analog front-end for higher resolution and channel density - making AD7798BRUZ optimal for 3-channel, low-power, self-contained sensor interfaces.

Availability

AD7798BRUZ is available at Aetrix Electronics and suitable for weigh scales, pressure transmitters, and portable medical devices requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for AD7798BRUZ 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, headquartered in Norwood, MA, with R&D and manufacturing facilities worldwide.

The AD7798 is part of Analog Devices' precision Σ-Δ ADC product line, engineered specifically for low-power, high-accuracy sensor signal conditioning in industrial, instrumentation, and medical applications where noise, drift, and integration matter.

FAQ

What is the maximum update rate supported by the AD7798BRUZ?

The AD7798BRUZ supports a software-programmable output update rate ranging from 4.17 Hz to 470 Hz. At 470 Hz, the effective resolution drops to 15.5 bits (peak-to-peak) with gain = 128, while maintaining 16-bit no-missing-codes performance. This range allows designers to optimize for either ultra-low noise (low update rates) or higher throughput (higher update rates) depending on application requirements. The AD7798BRUZ achieves this via configurable digital filter settings stored in its mode register.

Does the AD7798BRUZ require an external crystal or oscillator?

No, the AD7798BRUZ does not require an external crystal or oscillator. It integrates a 64 kHz ±3% internal clock oscillator, which drives the Σ-Δ modulator and digital filter. This eliminates BOM cost, PCB area, and layout sensitivity associated with external timing components. The internal clock can be overridden via the CLKSEL bit in the mode register if an external clock source is preferred for synchronization or jitter reduction - but it is not required for basic operation of the AD7798BRUZ.

How does the PSW pin function in the AD7798BRUZ?

The PSW (low-side power switch) pin on the AD7798BRUZ is an N-channel MOSFET output rated for ≤9 Ω RON at AVDD = 3 V and 30 mA continuous current. It connects between the selected analog input channel and GND, enabling controlled excitation of resistive sensors like strain gauges or RTDs. When asserted, PSW sinks current to activate bridge excitation; its on-resistance contributes minimal error (<0.1% at 10 mA), and it is fully compatible with the AD7798BRUZ's internal calibration routines.

Can the AD7798BRUZ operate with separate analog and digital supply voltages?

Yes, the AD7798BRUZ supports independent analog (AVDD) and digital (DVDD) supply rails, both rated from 2.7 V to 5.25 V. This allows AVDD to power the precision analog front end at 5 V while DVDD interfaces with a 3.3 V or 1.8 V microcontroller - eliminating level-shifting components and reducing noise coupling. The AD7798BRUZ maintains full specification compliance across all valid AVDD/DVDD combinations, including AVDD = 5 V and DVDD = 3.3 V simultaneously.

What is the purpose of the P1 and P2 pins on the AD7798BRUZ?

The P1 and P2 pins on the AD7798BRUZ are multifunction terminals that serve as either the positive/negative inputs of the third differential analog channel (AIN3(+)/AIN3(−)) or as general-purpose digital outputs referenced to AVDD and GND. Their function is configured via the IO register. As outputs, they support push-pull drive (VOH ≥ AVDD − 0.6 V, VOL ≤ 0.4 V) and can control LEDs, relays, or status indicators - adding system-level functionality without requiring external GPIO expanders. This dual-role capability is unique to the AD7798BRUZ among its family members.