Analog Devices Inc. AD8228BRMZ

Overview

AD8228BRMZ from Analog Devices is a precision instrumentation amplifier optimized for high-accuracy bridge signal conditioning. It delivers pin-strappable gains of 10 or 100, 2 ppm/°C gain drift (B grade), 50 μV max input offset voltage, and 100 dB CMRR at DC–60 Hz - enabling stable measurement in weigh scales and industrial process controls.

For engineers reviewing the AD8228BRMZ datasheet, AD8228BRMZ pinout, AD8228BRMZ application, or AD8228BRMZ equivalent, key selection criteria include guaranteed gain accuracy over temperature, low 0.8 μV/°C input offset drift, rail-to-rail output swing on ±2.3 V to ±18 V supplies, and internal laser-trimmed resistor networks eliminating external gain-setting components.

Technical Context

The AD8228BRMZ implements a classic three-op-amp architecture with internal, laser-trimmed resistors for gain setting - ensuring matched ratio accuracy and minimal drift. Its preamplifier stage provides differential gain while preserving common-mode level, followed by a precision difference amplifier that rejects residual common-mode voltage.

Gain is selected via pins G1 and G2: open for G = 10 (transfer function VOUT = 10 × (VIN+ − VIN−) + VREF), shorted for G = 100 (VOUT = 100 × (VIN+ − VIN−) + VREF). The reference terminal (REF) sets output common-mode level and supports single-supply ADC interfacing when biased externally.

Key Specifications

Pinout & Package

AD8228BRMZ is housed in an 8-lead MSOP package (3 mm × 3 mm, 0.65 mm pitch), optimized for space-constrained PCB layouts while maintaining thermal performance (θJA = 135°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD8221ARMZ and INA128UA, AD8228BRMZ provides the lowest guaranteed gain drift (2 ppm/°C), highest CMRR retention over frequency, and eliminates external resistor matching - making it the optimal choice for high-stability bridge signal chains where calibration intervals must exceed 12 months.

Availability

AD8228BRMZ is available at Aetrix Electronics and suitable for weigh scales, industrial process controls, and medical instrumentation requiring stable component supply and long-term parametric consistency.

Supply support for AD8228BRMZ 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 AD8228 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for DC-accurate bridge and transducer signal conditioning in harsh, wide-temperature industrial and medical environments.

FAQ

What gain options does the AD8228BRMZ support, and how are they configured?

The AD8228BRMZ supports two fixed gains: 10 and 100. Gain is selected solely by the state of pins G1 (Pin 2) and G2 (Pin 3): leave both pins unconnected for G = 10; short them together for G = 100. No external resistors or configuration registers are involved. This hardware-strapping method ensures deterministic, drift-free gain selection - a key advantage of the AD8228BRMZ over programmable alternatives.

How does the AD8228BRMZ achieve its low 2 ppm/°C gain drift specification?

The AD8228BRMZ achieves 2 ppm/°C gain drift (B grade) through monolithic integration and laser trimming of all internal gain-setting resistors. Unlike discrete-resistor-based instrumentation amplifiers, this process guarantees precise resistor ratio matching and identical temperature coefficients across the network. The result is a gain error that changes predictably and minimally with temperature - a critical feature confirmed in the AD8228BRMZ datasheet's Figure 20 and Table 2.

Can the AD8228BRMZ operate on a single supply, and what are the REF pin requirements?

Yes, the AD8228BRMZ operates on single or dual supplies (total supply range: +4.6 V to +36 V). When using a single supply, the REF pin must be biased to a stable voltage (e.g., mid-supply) to set output common-mode level. The AD8228BRMZ REF input has 20 kΩ input resistance and requires ≤1 Ω source impedance for optimal CMRR; higher impedances degrade common-mode rejection due to mismatched signal paths.

What is the maximum common-mode input voltage for AD8228BRMZ at ±15 V supplies and G = 100?

At ±15 V supplies and G = 100, the AD8228BRMZ supports a common-mode input voltage range of −13.0 V to +13.8 V (−VS + 2.0 V to +VS − 1.2 V) over −40°C to +85°C, per Table 3 and Figure 13. This wide range allows direct connection to high-common-mode bridge sensors without level-shifting circuitry - a verified capability documented in the AD8228BRMZ datasheet's "Input Operating Voltage Range" section.

Does AD8228BRMZ require external input protection, and what are its built-in safeguards?

The AD8228BRMZ includes ESD protection (2 kV HBM) and can tolerate continuous dc input overvoltage up to ±3.5 V beyond the supply rails. For transient overloads exceeding this (e.g., defibrillator pulses), external series resistors and low-leakage clamping diodes (e.g., BAV199L) are recommended. The AD8228BRMZ datasheet specifies a safe continuous input current limit of 6 mA, defining minimum series resistance values for specific overvoltage conditions.