Analog Devices Inc. AD621BRZ-R7

Overview

AD621BRZ-R7 from Analog Devices is a precision, low-power, bipolar-input instrumentation amplifier in an 8-lead SOIC package, featuring 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%. It is widely used in weigh scales, transducer interfaces, and battery-powered data acquisition systems.

For engineers reviewing the AD621BRZ-R7 datasheet, AD621BRZ-R7 pinout, AD621BRZ-R7 application, or AD621BRZ-R7 equivalent, key selection criteria include guaranteed gain accuracy over temperature, low drift (5 ppm/°C), RTI noise performance below 0.3 µV p-p (0.1–10 Hz), and compatibility with ±2.3 V to ±18 V dual supplies in space-constrained industrial and portable designs.

Technical Context

The AD621BRZ-R7 implements a modified three-op-amp topology with on-chip laser-trimmed thin-film gain resistors enabling precise, low-drift gains of 10 or 100. Its Superβeta bipolar input stage delivers 1.5 nA max input bias current over –40°C to +85°C while maintaining high CMRR (110 dB DC–60 Hz) and PSRR (110 dB).

Gain selection is achieved via external pin strapping between Pins 1 and 8 - open for G = 10, shorted for G = 100 - with internal architecture ensuring bandwidth scaling (800 kHz at G = 10, 200 kHz at G = 100) and transconductance optimization that reduces input voltage noise as gain increases.

Key Specifications

Pinout & Package

AD621BRZ-R7 is housed in an 8-lead SOIC (R-8) package, 3.9 mm × 4.9 mm, with standard JEDEC MS-012 outline and 1.27 mm pitch.

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-R7 uniquely balances pin-strappable dual gain, ultra-low 0.1–10 Hz noise, and sub-1.3 mA power in a compact SOIC - making it optimal for cost-sensitive, battery-constrained, and thermally stable precision measurement systems where gain flexibility and DC accuracy are jointly essential.

Availability

AD621BRZ-R7 is available at Aetrix Electronics and suitable for weigh scales, transducer interface circuits, and battery-powered portable equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for AD621BRZ-R7 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-R7 belongs to Analog Devices' precision instrumentation amplifier product line, designed specifically for high-accuracy, low-power sensor signal conditioning in applications demanding guaranteed total system error, minimal thermal drift, and robust operation across extended industrial temperature ranges.

FAQ

What gain options does the AD621BRZ-R7 support, and how are they configured?

The AD621BRZ-R7 supports two factory-trimmed gains: G = 10 (default, Pins 1 and 8 open) and G = 100 (Pins 1 and 8 shorted). No external resistors are required for these standard gains. The internal thin-film resistor network ensures 5 ppm/°C max gain drift and 0.15% max total gain error. External resistors may be added between Pins 1 and 8 for intermediate gains (e.g., G = 20, 50), though this degrades accuracy and TC.

Does the AD621BRZ-R7 require external components for basic operation?

No, the AD621BRZ-R7 operates fully functional with only dual power supplies (±2.3 V to ±18 V), input signals, and output load. Decoupling capacitors (0.1 µF ceramic near each supply pin) are strongly recommended for stability. The REF pin may be grounded, tied to mid-supply, or driven by a DAC - no pull-up/down resistors are needed. Gain configuration uses only a jumper or solder bridge between Pins 1 and 8.

What is the maximum continuous input overvoltage the AD621BRZ-R7 can withstand?

The AD621BRZ-R7 safely withstands ±3.0 V continuous differential input overvoltage with power on or off - exceeding typical bridge transducer fault conditions. This is enabled by integrated 400 Ω thin-film input resistors and back-to-back diodes protecting the Superβeta input transistors. For higher protection (e.g., ±15 V), external series resistors (e.g., 2 kΩ per input) increase robustness while raising input noise to 15 nV/√Hz - still competitive with discrete three-op-amp designs.

How does the AD621BRZ-R7 achieve low 0.1–10 Hz noise performance?

The AD621BRZ-R7 achieves 0.28 µV p-p RTI noise (0.1–10 Hz) through its proprietary bipolar Superβeta input stage, which minimizes 1/f noise corner frequency and base resistance contributions. Internal gain-resistor trimming and thermal symmetry reduce correlated drift, while the fixed-gain architecture avoids noise-amplifying external resistor Johnson noise. This performance is specified and tested across the full –40°C to +85°C range for the AD621BRZ-R7 B-grade device.

Can the AD621BRZ-R7 be used with a single 5 V supply?

Yes, the AD621BRZ-R7 operates from split supplies (±2.3 V to ±18 V) or a single 5 V supply with appropriate reference biasing. When using 5 V, connect –VS to ground, +VS to 5 V, and drive the REF pin to 2.5 V (e.g., via resistor divider or buffer) to center the output swing. Input common-mode range extends to within 1.9 V of either rail, allowing ±0.5 V differential signals at G = 10. Output swing reaches within 1.2 V of rails into 10 kΩ, supporting direct interfacing to 12-bit+ SAR ADCs.