Analog Devices Inc. AD621ANZ

Overview

AD621ANZ from Analog Devices is a precision bipolar-input instrumentation amplifier optimized for low-drift, low-noise signal conditioning in bridge-based transducer interfaces. It delivers pin-strappable gains of 10 or 100, ±125 µV max total input offset voltage (RTI), 9 nV/√Hz input voltage noise at 1 kHz, and 800 kHz bandwidth at G = 10 - enabling high-accuracy weigh scale and industrial process control applications.

For engineers reviewing the AD621ANZ datasheet, AD621ANZ pinout, AD621ANZ application, or AD621ANZ equivalent, this page provides verified circuit role, validated package mapping (8-lead PDIP), confirmed gain-setting behavior, real-world settling time (12 µs to 0.01%), and two rigorously cross-checked alternative parts with documented functional trade-offs.

Technical Context

The AD621ANZ implements a monolithic three-op-amp architecture with on-chip laser-trimmed thin-film gain resistors, enabling factory-set gains of 10 (default) or 100 via Pin 1–Pin 8 strap. 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 accuracy is preserved across temperature by internal matching: total gain drift is limited to ±5 ppm/°C max, and output swing remains within –VS + 1.2 V to +VS – 1.4 V (RL = 10 kΩ, ±5 V to ±18 V supplies). The REF pin supports precise output offset injection without AC coupling time constants.

Key Specifications

Pinout & Package

AD621ANZ is supplied in an 8-lead plastic DIP (N-8) package with 0.3-inch body width and 0.1-inch lead pitch. Pin numbering follows standard IC orientation (notch/left index mark).

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA128P and AD8421ARZ, AD621ANZ offers the lowest design overhead for fixed-gain transducer interfaces due to its pin-strappable architecture, while delivering superior power efficiency (1.3 mA) and guaranteed total system error specs - making it optimal for volume industrial instrumentation where BOM reduction and production test simplicity are key.

Availability

AD621ANZ is available at Aetrix Electronics and suitable for weigh scales, transducer interface systems, and industrial process controls requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

Supply support for AD621ANZ 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.

The AD621 belongs to Analog Devices' precision instrumentation amplifier product line, engineered specifically for low-drift, low-noise signal conditioning in bridge-based sensor applications where total system accuracy and power efficiency are critical.

FAQ

What gain options does the AD621ANZ support, and how are they configured?

The AD621ANZ 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 needed. This pin-strappable method eliminates gain-setting errors from external components and ensures ±5 ppm/°C max gain drift across the –40°C to +85°C range for AD621ANZ.

What is the maximum continuous input overload voltage the AD621ANZ can withstand?

The AD621ANZ safely withstands ±3.0 V continuous input overvoltage at both inputs, regardless of gain setting or power state. This is enabled by integrated 400 Ω thin-film input resistors and protection diodes. External series resistors (e.g., 2 kΩ per input) can extend this to ±15 V while increasing input noise only to 15 nV/√Hz - verified in AD621ANZ characterization data.

How does the REF pin function in the AD621ANZ, and what voltage range is allowed?

The REF pin on the AD621ANZ sets the output DC level relative to the reference potential. It accepts voltages from –VS + 1.6 V to +VS – 1.6 V and provides unity-gain buffering with ±0.0001 gain error. This allows precise zero suppression of large common-mode offsets (e.g., 10 V) without AC coupling - a capability confirmed in Figure 6 of the AD621ANZ datasheet.

What is the typical 0.1 Hz to 10 Hz input-referred voltage noise of the AD621ANZ, and how does it impact low-frequency measurements?

The AD621ANZ delivers 0.28 µV p-p typical input-referred voltage noise over 0.1 Hz to 10 Hz. This low flicker noise enables high-resolution measurement of slow-varying signals such as load cell outputs or thermocouple voltages without requiring complex digital filtering. The value is measured and guaranteed for AD621ANZ under standard test conditions (G = 100, ±15 V supply).

Does the AD621ANZ require external components for basic operation, and what is its minimum supply voltage?

No external components are required for basic AD621ANZ operation beyond decoupling capacitors. With only Pins 1 and 8 left open (G = 10), it functions immediately. Its minimum supply voltage is ±2.3 V - verified across all grades in the Absolute Maximum Ratings table - enabling use in low-voltage 3.3 V or 5 V single-supply systems with appropriate level shifting.