Analog Devices Inc. AD8228ARZ

Overview

AD8228ARZ from Analog Devices is a precision instrumentation amplifier optimized for low-drift bridge signal conditioning in industrial and medical systems. It delivers 2 ppm/°C gain drift (B grade, G=10), 50 μV max input offset voltage, and 100 dB CMRR at DC–60 Hz - enabling high-accuracy measurement of microvolt-level differential signals amid high common-mode voltages up to ±10 V.

For engineers reviewing the AD8228ARZ datasheet, AD8228ARZ pinout, AD8228ARZ application, or AD8228ARZ equivalent, key selection criteria include guaranteed gain accuracy over temperature, rail-to-rail output swing on ±2.3 V to ±18 V supplies, low 1.5 μV/°C offset drift (B grade), and dual fixed-gain configuration (10 or 100) via pin-strapping without external resistors.

Technical Context

The AD8228ARZ implements a laser-trimmed three-op-amp architecture with internal gain-setting resistors, eliminating external component mismatch as a source of error. Its preamplifier stage uses matched bipolar input transistors and precision thin-film resistors to achieve <0.8 μV/°C input offset drift and <2 ppm/°C gain drift.

Gain is selected by shorting (G = 100) or leaving open (G = 10) Pins 2 and 3; both configurations maintain full rail-to-rail output swing and retain >114 dB CMRR (DC–60 Hz, G = 100). The reference terminal supports precise level-shifting for single-supply ADC interfacing while maintaining 124 dB PSRR at DC.

Key Specifications

Pinout & Package

AD8228ARZ is housed in an 8-lead SOIC package (body width 3.9 mm, JEDEC MS-012), RoHS-compliant and rated for −40°C to +125°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD8228ARZ, AD8221ARZ trades guaranteed low drift for flexible gain, while INA128UA sacrifices precision for lower cost - making AD8228ARZ the optimal choice when metrology-grade stability is mandatory in fixed-gain bridge interfaces.

Availability

AD8228ARZ is available at Aetrix Electronics and suitable for weigh scales, industrial process controls, and medical instrumentation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AD8228ARZ 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 AD8228ARZ belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for DC-accurate, low-drift signal conditioning in bridge-based sensor systems operating from −40°C to +125°C.

FAQ

What are the valid supply voltage ranges for AD8228ARZ?

The AD8228ARZ operates from ±2.3 V to ±18 V dual supplies or single supplies from +4.6 V to +36 V. Performance is fully specified over −40°C to +85°C at all supply levels. At ±2.3 V, output swing is reduced to −VS + 1.1 V to +VS − 1.2 V (RL = 10 kΩ); at ±18 V, it extends to −VS + 1.6 V to +VS − 1.5 V. The AD8228ARZ remains functional up to +125°C ambient, though some parameters degrade outside the industrial grade range.

How do I configure AD8228ARZ for gain = 100?

To set AD8228ARZ to gain = 100, short Pin 2 (G1) and Pin 3 (G2) together using a zero-ohm resistor or solder bridge. Leave both pins unconnected for gain = 10. Do not float either pin - floating G1/G2 may cause undefined behavior. The transfer function becomes VOUT = 100 × (VIN+ − VIN−) + VREF. Verify continuity with a multimeter post-assembly, as parasitic capacitance >1 pF on these pins can degrade high-frequency CMRR.

Can AD8228ARZ drive a 12-bit SAR ADC directly?

Yes, AD8228ARZ can directly drive most 12-bit SAR ADCs. Its rail-to-rail output swing (e.g., −13.8 V to +13.6 V on ±15 V supplies) and 2 V/μs slew rate support full-scale step responses within settling time specifications. For 12-bit accuracy (LSB = 2.44 mV at 10 V range), the AD8228ARZ's 0.3 μV p-p 0.1–10 Hz noise and <10 ppm nonlinearity ensure no code missing or distortion. Use a 10 Ω series resistor + 1 nF capacitor at VOUT to isolate capacitive loads >100 pF.

What is the maximum allowable differential input voltage for AD8228ARZ at G = 100?

At gain = 100, the AD8228ARZ limits continuous differential input voltage to ≤5 V to prevent input current exceeding 6 mA - its absolute maximum safe input current. Exceeding this risks permanent damage. For applications with larger differential signals (e.g., defibrillator pulse detection), add identical series protection resistors: RPROTECT = (VDIFF_MAX − 5 V)/6 mA. Example: for 20 V max differential, use two 2.5 kΩ resistors (one per input) to limit current to 6 mA.

Does AD8228ARZ require external input protection in industrial environments?

The AD8228ARZ includes integrated ESD protection (2 kV HBM) and can tolerate dc overvoltage up to ±3.5 V beyond supplies. However, in harsh industrial settings with lightning-induced surges or inductive kickback, external protection is recommended: 10 kΩ series resistors per input + BAV199L low-leakage clamps to ±VS. This preserves the AD8228ARZ's 0.4 nA input bias current and avoids degrading CMRR from added source impedance mismatch. Always verify protection network does not reduce bandwidth below application needs.