Analog Devices Inc. AD8221ARM-REEL7

Overview

AD8221ARM-REEL7 from Analog Devices is a precision instrumentation amplifier in 8-lead MSOP package, delivering 80 dB CMRR to 10 kHz (G = 1), 825 kHz –3 dB bandwidth at unity gain, and 8 nV/√Hz input voltage noise. It features gain programmability via single external resistor (1–1000 V/V), ±2.3 V to ±18 V dual-supply operation, and is optimized for bridge sensor signal conditioning in industrial weigh scales and strain gage interfaces.

For engineers reviewing the AD8221ARM-REEL7 datasheet, AD8221ARM-REEL7 pinout, AD8221ARM-REEL7 application, or AD8221ARM-REEL7 equivalent, key selection criteria include its guaranteed 80 dB CMRR at 10 kHz, low 0.25 µV_p-p (0.1 Hz–10 Hz) RTI noise at G ≥ 100, ±40°C to +85°C specified performance range, and MSOP-8 footprint compatibility with space-constrained multichannel data acquisition systems.

Technical Context

The AD8221ARM-REEL7 implements a laser-trimmed 3-op-amp topology with superbeta input transistors and current-feedback architecture, enabling gain-bandwidth product increase with gain-e.g., 562 kHz at G = 10 versus 825 kHz at G = 1. Its balanced pinout (RG pins adjacent to inputs, REF next to VOUT) minimizes parasitic coupling to sustain high CMRR over frequency.

It supports level-shifting via the REF terminal, accepts ±10 V input common-mode voltages across full supply range, and maintains 100 dB CMRR at 10 kHz for G = 100. Input bias current remains ≤ 2 nA (typ 0.5 nA) over −40°C to +85°C, with 0.9 µV/°C max input offset drift in ARM grade.

Key Specifications

Pinout & Package

AD8221ARM-REEL7 is housed in an 8-lead MSOP package (3.0 mm × 3.0 mm, 0.5 mm pitch), requiring half the PCB area of SOIC-8 and optimized for high-density layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with AD8221ARM-REEL7, AD8421ARMZ delivers superior CMRR and lower bias current but requires PCB redesign for 10-pin MSOP; INA128UA offers lower unit cost in SOIC but sacrifices MSOP density and high-frequency rejection capability-making AD8221ARM-REEL7 the optimal balance of size, performance, and cost for space-limited industrial DAQ.

Availability

AD8221ARM-REEL7 is available at Aetrix Electronics and suitable for industrial process controls, precision data acquisition systems, and medical instrumentation requiring stable component supply and long-term manufacturing continuity.

Supply support for AD8221ARM-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD8221 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for high-accuracy, low-drift sensor signal conditioning in harsh industrial and medical environments.

FAQ

What is the maximum gain error specification for AD8221ARM-REEL7 at G = 100?

The AD8221ARM-REEL7 has a maximum gain error of 0.3% at G = 100, as specified in Table 1 of the Rev. C datasheet under ARM grade conditions. This error includes contributions from internal laser-trimmed resistors and is measured with V_OUT = ±10 V. External RG resistor tolerance directly impacts total system gain accuracy, so 0.1% metal-film resistors are recommended for sub-0.1% overall error.

Can AD8221ARM-REEL7 operate from a single +5 V supply?

No, AD8221ARM-REEL7 requires dual supplies (±2.3 V to ±18 V) or split-rail configuration; it does not support true single-supply operation. While the input common-mode range extends to within 1.9 V of each rail, the device lacks rail-to-rail input/output stages needed for unipolar 0 V to +5 V operation. For single-supply designs, consider the AD8237 or AD8420 as alternatives.

What is the purpose of the REF pin on AD8221ARM-REEL7, and what voltage range is safe?

On AD8221ARM-REEL7, the REF pin sets the output DC level relative to the chosen reference potential-enabling level-shifting for ADC interfacing. The safe voltage range is −V_S to +V_S, but Analog Devices specifies that REF must not exceed either supply rail by more than 0.5 V. For ±15 V supplies, REF must remain between −15.5 V and +15.5 V; typical use ties REF to ground or mid-supply (e.g., +2.5 V) for bipolar ADCs.

How does AD8221ARM-REEL7 achieve 80 dB CMRR at 10 kHz when most competitors degrade below 200 Hz?

AD8221ARM-REEL7 achieves 80 dB CMRR at 10 kHz through a combination of laser-trimmed thin-film resistors, superbeta input transistors with matched IB compensation, and a uniquely balanced pinout (RG pins adjacent to inputs, REF next to VOUT) that minimizes parasitic capacitance asymmetry. This layout and trimming strategy suppresses frequency-dependent CMRR roll-off inherent in conventional 3-op-amp topologies.

Is AD8221ARM-REEL7 RoHS compliant and lead-free?

Yes, AD8221ARM-REEL7 is RoHS compliant and lead-free. Per Analog Devices' official product change notice (PCN-14-0103), all MSOP-packaged AD8221 variants-including AD8221ARM-REEL7-have been manufactured in lead-free, halogen-free, and RoHS-compliant processes since 2014. The "ARM" suffix denotes the MSOP-8 package with Pb-free matte tin finish.