Analog Devices Inc. AD7718BRUZ

Overview

AD7718BRUZ from Analog Devices is a 24-bit Σ-Δ analog-to-digital converter (ADC) with integrated programmable-gain amplifier (PGA), rail-to-rail input buffer, and on-chip 32.768 kHz crystal oscillator/PLL. It supports up to 10 pseudo-differential or 5 fully-differential analog input channels, delivers 18-bit peak-to-peak resolution at ±2.56 V range with 20 Hz update rate (CHOP = 0), and enables simultaneous 50 Hz/60 Hz rejection for precision industrial sensor interfacing.

For engineers reviewing the AD7718BRUZ datasheet, AD7718BRUZ pinout, AD7718BRUZ application, or AD7718BRUZ equivalent, key selection considerations include its 24-bit resolution, factory-calibrated performance, VREF Select™ ratiometric/absolute measurement capability, 3-wire SPI/QSPI/MICROWIRE compatibility, and pin-for-pin upgrade path from the 16-bit AD7708BRUZ in TSSOP-28 packaging.

Technical Context

The AD7718BRUZ implements a chopper-stabilized Σ-Δ modulator architecture with digital filtering, supporting two operational modes: CHOP = 0 (optimized for analog performance, 5.4–105 Hz output rates) and CHOP = 1 (optimized for channel throughput, 16.06 Hz–1.365 kHz). Its dual reference inputs (REFIN1/REFIN2) allow flexible configuration as either reference sources or additional analog inputs (AIN9/AIN10).

It integrates a 2-bit digital I/O port, serial interface logic with Schmitt-triggered SCLK, and independent AVDD/DVDD supplies (2.7–3.6 V or 4.75–5.25 V). The device achieves ≥100 dB normal-mode rejection at 50/60 Hz and ≥110 dB common-mode rejection (DC, 50/60 Hz) on ±20 mV range - critical for low-level transducer signal acquisition without external conditioning.

Key Specifications

Pinout & Package

AD7718BRUZ is housed in a 28-lead TSSOP package (RU-28), RoHS-compliant, with 0.65 mm lead pitch and exposed pad for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7708BRUZ, AD7718BRUZ delivers 8 extra bits of resolution and superior 50/60 Hz rejection, while ADS1248IPWR offers faster sampling but lacks the integrated crystal oscillator and pin compatibility - making AD7718BRUZ optimal for precision, low-noise, drop-in-upgrade scenarios.

Availability

AD7718BRUZ is available at Aetrix Electronics and suitable for industrial process control, portable instrumentation, and smart transmitter designs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7718BRUZ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7718BRUZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered for low-frequency, high-accuracy measurement applications including sensor conditioning, weigh scales, and analytical instrumentation.

FAQ

What is the maximum achievable peak-to-peak resolution of the AD7718BRUZ?

The AD7718BRUZ achieves up to 18-bit peak-to-peak resolution when configured for ±2.56 V input range with 20 Hz output update rate and CHOP = 0 mode. This value is measured under specified conditions (B-grade, AVDD = 3 V, REFIN = 2.5 V) and reflects effective noise-free code resolution - not theoretical ENOB. At higher update rates or in CHOP = 1 mode, resolution decreases to maintain throughput.

Does the AD7718BRUZ require an external crystal oscillator?

No, the AD7718BRUZ includes an on-chip oscillator buffer and PLL that accept a standard 32.768 kHz tuning-fork crystal directly on XTAL1/XTAL2 pins. No external capacitors or driver circuitry are needed. The internal PLL generates all required internal clocks, enabling full functionality with minimal external components - a key advantage over alternatives requiring external clock sources.

Can the AD7718BRUZ measure both ratiometric and absolute voltage signals in the same system?

Yes, the AD7718BRUZ implements VREF Select™ technology, allowing runtime selection between ratiometric mode (where REFIN tracks sensor excitation voltage) and absolute mode (using a fixed 2.5 V reference). This is controlled via the ADC Control Register, enabling a single hardware design to support diverse sensor types - such as strain gauges (ratiometric) and thermocouples (absolute) - without external component changes.

How does the CHOP mode affect performance and timing in the AD7718BRUZ?

CHOP = 0 (chopper-stabilized mode) optimizes offset drift and 1/f noise, delivering 10 nV/°C offset drift and ≥110 dB CMRR at DC/50/60 Hz, but limits max update rate to 105 Hz. CHOP = 1 disables chopping, doubling throughput (up to 1.365 kHz) at the expense of higher offset drift (200 nV/°C) and reduced CMRR - making it ideal for multiplexed, high-channel-count systems where speed outweighs ultimate precision.

Is the AD7718BRUZ pin-compatible with any other Analog Devices ADCs?

Yes, the AD7718BRUZ is pin-for-pin compatible with the AD7708BRUZ (16-bit version) in both SOIC and TSSOP packages. They share identical pin functions, register maps, and timing - enabling seamless hardware upgrades from 16-bit to 24-bit resolution without PCB redesign. This compatibility is explicitly confirmed in the AD7708/AD7718 datasheet Rev. 0, page 1.