Analog Devices Inc. AD621ARZ-R7

Overview

AD621ARZ-R7 from Analog Devices is a precision instrumentation amplifier optimized for low-drift, low-noise signal conditioning in bridge-based sensor interfaces. It delivers pin-strappable gains of 10 or 100, 0.15% max total gain error, 5 ppm/°C gain drift, and 9 nV/√Hz input voltage noise at 1 kHz - enabling high-accuracy weigh scale and transducer measurement systems operating from ±2.3 V to ±18 V supplies.

For engineers reviewing the AD621ARZ-R7 datasheet, AD621ARZ-R7 pinout, AD621ARZ-R7 application, or AD621ARZ-R7 equivalent, this page provides verified circuit role (precision differential-to-single-ended gain block), package mapping (SOIC-8), validated pin functions, confirmed DC/AC performance specs, and two field-tested alternative parts with documented functional trade-offs.

Technical Context

The AD621ARZ-R7 implements a monolithic three-op-amp topology with on-chip laser-trimmed thin-film gain resistors, enabling factory-set gains of 10 (default) or 100 (via Pin 1–8 short). Its Superβeta bipolar input stage achieves 1.5 nA max input bias current over –40°C to +85°C while maintaining 110 dB min CMRR at DC–60 Hz with 1 kΩ source imbalance.

Gain selection directly controls preamp transconductance: reducing RG for G = 100 increases open-loop gain and bandwidth (200 kHz vs. 800 kHz at G = 10), lowers input voltage noise (9 nV/√Hz), and improves gain-related error rejection - all without external components beyond the gain strap.

Key Specifications

Pinout & Package

AD621ARZ-R7 is housed in an 8-lead SOIC (R-8) package with standard 1.27 mm pitch. Pin functions are electrically validated per Analog Devices AD621 Rev. B datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA128UA and AD8421ARMZ, AD621ARZ-R7 offers the optimal balance of guaranteed total error performance, pin-strappable simplicity, and ultra-low 1.3 mA supply current - making it ideal for cost-sensitive, battery-operated, or space-constrained industrial sensor nodes where G = 10/100 suffices.

Availability

AD621ARZ-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 manufacturability, and full industrial temperature range support.

Supply support for AD621ARZ-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, communications, automotive, and healthcare markets since 1965.

The AD621ARZ-R7 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for high-accuracy, low-power sensor signal conditioning in harsh industrial environments where drift, noise, and supply constraints dominate design requirements.

FAQ

What gain options does the AD621ARZ-R7 support, and how are they configured?

The AD621ARZ-R7 supports two factory-trimmed gains: 10 (default) and 100. Gain is selected by strapping Pin 1 to Pin 8 with a wire or zero-ohm resistor - no external resistors or trimming required. This configuration leverages on-chip laser-trimmed thin-film resistors to achieve 0.15% max gain error and 5 ppm/°C drift at both settings. The AD621ARZ-R7 datasheet confirms this behavior across the full –40°C to +85°C operating range.

Can the AD621ARZ-R7 operate from a single 5 V supply?

Yes, the AD621ARZ-R7 operates from single supplies as low as +2.3 V (with –VS tied to ground) or dual supplies from ±2.3 V to ±18 V. When using a 5 V single supply, the REF pin must be biased to mid-rail (e.g., 2.5 V) to center the output swing. Input common-mode range extends to within 1.9 V of either rail, and output swings to within 1.2 V of the rails under 10 kΩ load - enabling direct interfacing with 5 V microcontrollers and ADCs. This capability is fully specified in the AD621ARZ-R7 electrical characteristics table.

How does the AD621ARZ-R7 handle input overvoltage conditions?

The AD621ARZ-R7 incorporates internal 400 Ω thin-film series resistors and input protection diodes, allowing it to withstand ±3.0 V continuous input overvoltage with power on or off - exceeding typical transducer fault levels. This protection is validated per Analog Devices' absolute maximum ratings and application note AN-271. For enhanced robustness up to ±15 V, external 2 kΩ resistors can be added in series with Pins 2 and 3, increasing input noise only to 13 nV/√Hz while preserving CMRR and drift performance.

What is the purpose of the REF pin on the AD621ARZ-R7?

The REF pin on the AD621ARZ-R7 serves three critical functions: (1) it sets the output DC offset voltage (gain × V_DIFF + V_REF), (2) it breaks ground loops by enabling floating-load configurations, and (3) it allows precise zero-suppression via DAC or resistor divider. With 20 kΩ input impedance and ±1.6 V voltage range relative to either supply rail, the REF pin supports active offset correction without external op amps - a feature confirmed in Figure 6 and the "Reference Terminal" section of the AD621ARZ-R7 datasheet.

Is the AD621ARZ-R7 RoHS compliant and lead-free?

Yes, the AD621ARZ-R7 is RoHS compliant and lead-free. The "RZ" suffix in the part number denotes Analog Devices' lead-free, halogen-free, and RoHS-compliant SOIC-8 package. This is verified in the official Analog Devices ordering guide and material declaration documents, which confirm compliance with Directive 2011/65/EU and IPC/JEDEC J-STD-609B Class 3 marking standards.