Analog Devices Inc. AD7718BRZ-REEL7

Overview

AD7718BRZ-REEL7 from Analog Devices is a 24-bit Σ-Δ analog-to-digital converter (ADC) with integrated programmable gain amplifier (PGA), 10-channel pseudo-differential or 5-channel fully differential input capability, on-chip 32.768 kHz crystal oscillator and PLL, and 3-wire SPI-compatible serial interface. It delivers up to 18 bits peak-to-peak resolution at ±2.56 V input range with CHOP = 0 mode and supports simultaneous 50 Hz/60 Hz rejection for industrial sensor signal acquisition.

For engineers reviewing the AD7718BRZ-REEL7 datasheet, AD7718BRZ-REEL7 pinout, AD7718BRZ-REEL7 application, or AD7718BRZ-REEL7 equivalent, key selection considerations include its 24-bit resolution, factory-calibrated offset/gain performance, rail-to-rail input buffer, dual reference inputs (REFIN1/REFIN2), and pin compatibility with the 16-bit AD7708 for scalable system design.

Technical Context

The AD7718BRZ-REEL7 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 update rate) and CHOP = 1 (optimized for throughput, 16.06 Hz–1.365 kHz). Its PGA offers gain settings from 1 to 128, enabling direct digitization of low-level transducer signals from ±20 mV to ±2.56 V without external amplification.

It features dual configurable reference inputs (REFIN1 and REFIN2), each supporting ratiometric or absolute measurement via VREF Select™, and includes a 2-bit digital I/O port. The device uses separate analog (AVDD/AGND) and digital (DVDD/DGND) supplies, with independent power domains and strict ground isolation requirements to maintain 110 dB common-mode rejection at DC on the ±20 mV range.

Key Specifications

Pinout & Package

AD7718BRZ-REEL7 is housed in a 28-lead SOIC package (R-28), RoHS-compliant and tape-and-reel packaged per the -REEL7 suffix. Pin layout follows standard Analog Devices 28-pin SOIC footprint with exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7708BRZ-REEL7, the AD7718BRZ-REEL7 provides 8 additional resolution bits and enhanced noise performance at low update rates, while ADS1256IPWR trades built-in oscillator and dual-reference flexibility for higher speed-making AD7718BRZ-REEL7 optimal for low-noise, low-power, line-immune industrial sensing.

Availability

AD7718BRZ-REEL7 is available at Aetrix Electronics and suitable for industrial process control, smart transmitter design, and portable instrumentation requiring stable component supply, long-term manufacturability, and guaranteed RoHS compliance.

Supply support for AD7718BRZ-REEL7 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 Wilmington, MA, serving industrial, automotive, communications, and healthcare markets.

The AD7718BRZ-REEL7 belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-frequency, high-accuracy measurement applications including sensor interfaces, weigh scales, and analytical instrumentation where noise, drift, and line-frequency interference must be minimized.

FAQ

What is the maximum achievable peak-to-peak resolution of the AD7718BRZ-REEL7?

The AD7718BRZ-REEL7 achieves up to 18 bits peak-to-peak resolution at the ±2.56 V input range when operating in CHOP = 0 mode with a 20 Hz output update rate. At the ±20 mV range under the same conditions, it delivers 13 bits p-p. These values are measured and specified in the AD7718 datasheet Rev. 0, Table on page 4, and reflect real-world effective resolution after noise shaping and digital filtering.

Does the AD7718BRZ-REEL7 require an external crystal oscillator?

No, the AD7718BRZ-REEL7 integrates a buffered 32.768 kHz crystal oscillator circuit. External crystals connected between XTAL1 and XTAL2 are supported, but no external oscillator IC or clock generator is needed. The internal PLL generates all required internal clocks, eliminating BOM components and layout complexity associated with external timing sources.

Can the AD7718BRZ-REEL7 interface directly with a 3.3 V microcontroller SPI bus?

Yes, the AD7718BRZ-REEL7 supports 3 V digital operation: its logic inputs accept VINL ≤ 0.4 V and VINH ≥ 2.0 V at DVDD = 3 V, and outputs drive VOH ≥ DVDD − 0.6 V and VOL ≤ 0.4 V at 100 µA load. This ensures robust interoperability with standard 3.3 V MCUs without level-shifting circuitry.

How does the VREF Select™ feature work on the AD7718BRZ-REEL7?

VREF Select™ allows dynamic configuration of the AD7718BRZ-REEL7's reference architecture: REFIN1 and REFIN2 can be used simultaneously-one as the ADC reference and the other as an analog input (e.g., AIN9/AIN10)-enabling true ratiometric measurement where sensor excitation voltage serves as the reference, improving accuracy against supply variations.

Is the AD7718BRZ-REEL7 pin-compatible with any lower-resolution alternatives?

Yes, the AD7718BRZ-REEL7 is pin-for-pin compatible with the AD7708BRZ-REEL7 (16-bit version), sharing identical SOIC-28 packaging, pin functions, register map, and serial interface protocol. This enables seamless hardware upgrades from 16-bit to 24-bit resolution without PCB changes or firmware rearchitecture.