Analog Devices Inc. AD8422BRZ

Overview

AD8422BRZ from Analog Devices is a high-precision, low-power, rail-to-rail instrumentation amplifier optimized for dc-critical sensor signal conditioning. It delivers 150 dB CMRR at G = 1000, 0.04% max gain error (G = 1000), and 0.3 µV/°C input offset drift, enabling accurate bridge measurements in medical instrumentation and industrial process control.

For engineers reviewing the AD8422BRZ datasheet, AD8422BRZ pinout, AD8422BRZ application, or AD8422BRZ equivalent, this page provides verified specifications, SOIC_N package details, real-world use cases, and validated alternative options for precision analog front-end design.

Technical Context

The AD8422BRZ implements a laser-trimmed 3-op-amp topology with superbeta input transistors, achieving ultralow input bias current (0.5 nA max) and high common-mode rejection across frequency and temperature. Its architecture replicates differential input voltage across the external RG resistor to set gain from 1 to 1000.

Input overvoltage protection allows ±40 V operation relative to opposite supply rail without noise degradation, while rail-to-rail output swing (−VS + 0.2 V to +VS − 0.2 V, RL = 10 kΩ) supports single-supply systems down to 4.6 V. The reference pin enables precise output level shifting for unipolar ADC interfacing.

Key Specifications

Pinout & Package

AD8422BRZ is packaged in an 8-lead SOIC_N (R-8) with exposed pad, rated for −40°C to +85°C operation. Thermal resistance θJA = 113°C/W (JEDEC 4-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD8421ARMZ and INA828IDR, AD8422BRZ offers the highest dc precision (150 dB CMRR, 0.04% gain error) and lowest power (368 µA) in SOIC_N, making it optimal for battery-powered, high-accuracy sensor nodes where thermal stability and long-term calibration hold are essential.

Availability

AD8422BRZ is available at Aetrix Electronics and suitable for medical instrumentation, industrial process controls, and precision data acquisition systems requiring stable component supply and long-term lifecycle support.

Supply support for AD8422BRZ 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, serving precision measurement, industrial automation, and healthcare markets.

The AD8422 product line delivers third-generation instrumentation amplifiers with industry-leading precision-per-microampere efficiency, specifically engineered for dc-critical sensor interfaces in harsh, space-constrained, and power-limited environments.

FAQ

What is the maximum allowable input voltage beyond the supply rails for AD8422BRZ?

The AD8422BRZ supports continuous input voltages up to 40 V beyond the opposite supply rail-for example, −IN or +IN may reach −VS + 40 V or +VS − 40 V. This robust input overvoltage protection eliminates external clamping diodes in bridge sensor applications where transient surges occur. The specification applies across all gains and temperatures, and AD8422BRZ maintains full performance within these limits without latch-up or parametric shift.

Does AD8422BRZ require an external gain-setting resistor for G = 1 operation?

No, AD8422BRZ defaults to G = 1 when no resistor is connected across pins 2 and 3 (RG terminals). The internal architecture ensures minimal gain error (0.03% typ) and negligible gain drift at unity gain without external components. Adding an RG resistor is only necessary when setting gains >1, using the formula G = 1 + (19.8 kΩ/RG); AD8422BRZ's laser-trimmed core guarantees accuracy even with standard 1% resistors.

What is the operating temperature range for AD8422BRZ in SOIC_N packaging?

AD8422BRZ in the 8-lead SOIC_N package is specified for −40°C to +85°C for full performance compliance, including CMRR ≥146 dB (G = 1000), gain error ≤0.04%, and quiescent current ≤400 µA. Its extended operating range reaches −40°C to +125°C, though certain parameters (e.g., CMRR, offset drift) are not guaranteed beyond +85°C per the datasheet's specified performance envelope.

Can AD8422BRZ drive a 2 kΩ load while maintaining rail-to-rail output swing?

Yes, AD8422BRZ delivers rail-to-rail output swing into 2 kΩ loads: at ±15 V supplies, output swings from −VS + 0.25 V to +VS − 0.25 V (i.e., −14.75 V to +14.75 V). At cold temperatures, the negative swing degrades slightly to −VS + 0.3 V due to output stage limitations, but full swing remains usable across industrial temperature ranges. This capability enables direct interface with low-impedance ADC inputs or analog multiplexers without buffer amplifiers.

How does the REF pin function in AD8422BRZ, and what are its drive requirements?

The REF pin in AD8422BRZ sets the output voltage offset: VOUT = G × (VIN+ − VIN−) + VREF. To avoid injecting error, the REF node must be driven by a low-impedance source (<1 Ω), such as a precision voltage reference buffered by an op-amp. The pin is protected by ESD diodes and must remain within ±0.3 V of either supply rail. Using REF enables unipolar output scaling for single-supply ADCs-e.g., shifting a ±10 V output to 0–20 V range-without adding external summing circuitry.