Analog Devices Inc. AD621ARZ-RL

Overview

AD621ARZ-RL from Analog Devices is a low-drift, low-power instrumentation amplifier in an 8-lead SOIC package, delivering pin-strappable gains of 10 or 100, ±2.3 V to ±18 V supply operation, 1.3 mA max quiescent current, and 0.15% max total gain error - ideal for precision bridge transducer interfaces in weigh scales and industrial process control systems.

For engineers reviewing the AD621ARZ-RL datasheet, AD621ARZ-RL pinout, AD621ARZ-RL application, or AD621ARZ-RL equivalent, key selection criteria include guaranteed gain accuracy over temperature (±5 ppm/°C), 9 nV/√Hz input voltage noise at 1 kHz, 12 µs settling time to 0.01%, and full specification as a total system - eliminating discrete error budgeting.

Technical Context

The AD621ARZ-RL implements a monolithic three-op-amp architecture with on-chip laser-trimmed gain resistors enabling precise fixed gains of 10 (default) or 100 (via Pin 1–8 strap). Its Superβeta bipolar input stage delivers 1.5 nA max input bias current and 10² GΩ input impedance while maintaining low voltage noise.

Gain setting directly controls preamp transconductance: reducing RG for higher gain boosts open-loop gain, increases gain-bandwidth product, and lowers input voltage noise - resulting in 800 kHz bandwidth at G = 10 and 200 kHz at G = 100, with 0.75 V/µs slew rate and rail-sensing output swing.

Key Specifications

Pinout & Package

AD621ARZ-RL is supplied in an 8-lead SOIC (R-8) package, 3.9 mm × 4.9 mm body, 1.27 mm pitch, with exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA128UA and AD8421ARMZ, the AD621ARZ-RL uniquely balances ultra-low drift (0.6 µV/°C), pin-strappable fixed gains, and sub-1.5 mA power - making it the optimal choice for cost-sensitive, battery-operated, high-accuracy transducer signal chains where design simplicity and guaranteed system-level specs are prioritized.

Availability

AD621ARZ-RL is available at Aetrix Electronics and suitable for weigh scales, industrial process controls, and battery-powered portable equipment requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to +85°C.

Supply support for AD621ARZ-RL 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 AD621 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for high-accuracy, low-power sensor signal conditioning in harsh environments - emphasizing total system error guarantees, thermal stability, and ease of use over discrete alternatives.

FAQ

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

The AD621ARZ-RL supports two factory-trimmed gains: G = 10 (default, Pins 1 and 8 open) and G = 100 (Pins 1 and 8 shorted). This pin-strapping eliminates external resistor matching errors and guarantees 0.15% max total gain error. The AD621ARZ-RL does not support programmable gains between 10 and 100 without degrading accuracy and temperature coefficient.

What is the maximum continuous input overvoltage the AD621ARZ-RL can withstand?

The AD621ARZ-RL safely withstands ±3.0 V continuous input overvoltage at both inputs - independent of gain setting or power state. This is achieved via integrated 400 Ω thin-film input resistors and diode clamps. External series resistors (e.g., 2 kΩ per input) extend protection to ±15 V while increasing input noise to 15 nV/√Hz.

How does the REF pin function in the AD621ARZ-RL, and what voltage range is allowed?

The REF pin sets the output DC offset: V_OUT = G × (V_+IN – V_–IN) + V_REF. It accepts voltages from (–V_S + 1.6 V) to (+V_S – 1.6 V), enabling level-shifting, ground-loop elimination, and precise zero suppression. Driving REF with a DAC (e.g., AD548) allows dynamic offset cancellation without AC coupling time constants.

What is the guaranteed total input offset voltage for the AD621ARZ-RL over temperature?

The AD621ARZ-RL (B grade) guarantees ≤125 µV total input offset voltage at ±15 V supply and ≤215 µV over the full –40°C to +85°C range. Its average offset drift is 0.6 µV/°C max, limiting total drift-induced error to <40 µV across the operating temperature span - critical for uncalibrated high-resolution measurements.

Can the AD621ARZ-RL operate from a single supply, and what are the input/output voltage limitations?

Yes, the AD621ARZ-RL supports single-supply operation (e.g., +5 V and GND) with appropriate reference biasing. Input common-mode range extends to within 1.9 V of each rail; output swing reaches within 1.2 V of each rail at ±5 V supply. For single +5 V, configure REF at 2.5 V and ensure inputs stay between 1.1 V and 3.9 V to avoid saturation.