Analog Devices Inc. AD621BRZ

Overview

AD621BRZ from Analog Devices is a precision, low-power, bipolar-input instrumentation amplifier in an 8-lead SOIC package, delivering pin-strappable gains of 10 or 100, 0.15% max total gain error, 9 nV/√Hz input voltage noise at 1 kHz, and 12 µs settling time to 0.01% - widely deployed in weigh scales and transducer interface circuits for high-accuracy DC-coupled signal conditioning.

For engineers reviewing the AD621BRZ datasheet, AD621BRZ pinout, AD621BRZ application, or AD621BRZ equivalent, key selection criteria include guaranteed gain accuracy over temperature, RTI offset voltage drift ≤1.0 µV/°C (B grade), supply range ±2.3 V to ±18 V, and compatibility with low-noise, high-impedance sensor sources such as pressure bridges and load cells.

Technical Context

The AD621BRZ implements a monolithic three-op-amp architecture with on-chip laser-trimmed thin-film gain resistors enabling fixed gains of 10 (default) or 100 (via Pin 1–8 strap), achieving 5 ppm/°C max gain drift and 0.6 µV/°C max offset drift (B grade). Its Superβeta bipolar input stage delivers 1.5 nA max input bias current over –40°C to +85°C while maintaining 10² GΩ input impedance.

Gain-setting is fully internalized: no external resistors required for G = 10 or 100; optional external resistor between Pins 1 and 8 enables programmable gains from 10 to 100. The REF pin provides direct output offset control with 1 ± 0.0001 gain and ±VS − 1.6 V input voltage range, supporting zero-suppression in wide-dynamic-range applications.

Key Specifications

Pinout & Package

AD621BRZ is supplied in an 8-lead plastic SOIC (R-8) package, 5.0 mm × 6.2 mm body, 1.27 mm pitch, RoHS-compliant, with thermal resistance θ_JA = 155°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA128UA and AD8421ARMZ, the AD621BRZ uniquely balances ultra-low drift (0.6 µV/°C), pin-strappable gain, and 1.3 mA power in a single SOIC - making it optimal for cost-sensitive, battery-operated, or thermally constrained industrial weighing and transducer systems where guaranteed DC accuracy is non-negotiable.

Availability

AD621BRZ is available at Aetrix Electronics and suitable for weigh scales, transducer interface and data acquisition systems, and battery-powered portable equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD621BRZ 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 industrial, automotive, communications, and healthcare markets since 1965.

The AD621BRZ belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for DC-accurate, low-power signal conditioning in sensor front-ends where gain stability, offset drift, and noise performance directly determine measurement fidelity.

FAQ

What is the maximum continuous input overvoltage the AD621BRZ can withstand?

The AD621BRZ safely withstands ±3.0 V continuous input overvoltage at both inputs - with power on or off - thanks to integrated 400 Ω thin-film resistors and input protection diodes. This protects against transducer faults or supply sequencing errors without latch-up or permanent parameter shift. External series resistors (e.g., 2 kΩ per input) extend this to ±15 V while increasing input noise only to 15 nV/√Hz.

Does the AD621BRZ require external resistors to set gain of 10 or 100?

No. The AD621BRZ has factory-laser-trimmed internal gain resistors. Gain = 10 is the default configuration (Pins 1 and 8 open); Gain = 100 is selected by shorting Pins 1 and 8 with a wire or 0 Ω resistor. No external resistors are needed for either standard gain, ensuring accuracy and eliminating layout sensitivity.

What is the operating temperature range specified for the AD621BRZ?

The AD621BRZ is rated for –40°C to +85°C for full performance compliance. This range covers industrial environments including factory floors, outdoor process enclosures, and portable medical devices. The B-grade version (as indicated by 'B' in AD621BRZ) guarantees tighter offset drift (0.6 µV/°C) and lower initial offset (50 µV max) across this entire span.

Can the AD621BRZ be used with single-supply operation?

Yes - the AD621BRZ supports single-supply operation by tying –VS to ground and applying +VS to a positive rail (e.g., +5 V). Input common-mode range extends to –VS + 1.9 V, so with ground-referenced –VS, inputs must stay ≥ +1.9 V. The REF pin can be biased to mid-supply to center the output swing. Full specifications apply only under dual-supply conditions unless explicitly tested for single-supply.

How does the REF pin function in the AD621BRZ?

The REF pin of the AD621BRZ provides unity-gain, buffered access to the output offset voltage. Driving REF with a DAC or precision voltage source injects a controlled DC offset at the output without affecting gain or CMRR. It enables zero suppression (e.g., removing 1 V sensor offset), breaks ground loops, and supports floating loads - all while maintaining 1 ± 0.0001 gain accuracy from REF to OUTPUT.