Analog Devices Inc. AD629ANZ

Overview

AD629ANZ from Analog Devices is a precision unity-gain difference amplifier engineered for high common-mode voltage measurement, delivering ±270 V input common-mode range, ±13 V differential input range, and 500 kHz bandwidth with 86 dB CMRR at 500 Hz (B-grade). It replaces isolation amplifiers in battery cell monitoring and motor control current sensing where galvanic isolation is unnecessary.

For engineers reviewing the AD629ANZ datasheet, AD629ANZ pinout, AD629ANZ application, or AD629ANZ equivalent, this page provides verified specifications, functional pin mapping, real-world use cases in high-voltage sensing, and validated alternative options for industrial power electronics design.

Technical Context

The AD629ANZ integrates a precision op amp with a laser-trimmed 20:1 internal resistor network that attenuates the noninverting input signal before amplification, enabling rejection of ±270 V common-mode voltages while preserving differential gain of exactly 1. Its super beta input stage delivers low offset drift (10 μV/°C max for B-grade) and high open-loop gain (>20 million) to minimize gain error dependence on op amp performance.

Input protection withstands ±500 V common-mode and differential transients; output swings ±10 V on ±12 V supply into 2 kΩ load. The device operates across ±2.5 V to ±18 V supplies and is guaranteed over −40°C to +85°C in the 8-lead PDIP package (N-8).

Key Specifications

Pinout & Package

AD629ANZ is packaged in an 8-lead plastic dual in-line package (PDIP, N-8), with lead pitch 0.1 inch and body width 0.3 inches. Pin 8 is no-connect and must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA117P and AD8479ARZ, AD629ANZ offers the best balance of ±270 V common-mode capability, 86 dB CMRR, and PDIP packaging for legacy industrial PCBs - delivering verified performance at lower unit cost than AD8479ARZ while significantly exceeding INA117P's voltage and accuracy limits.

Availability

AD629ANZ is available at Aetrix Electronics and suitable for battery management systems, industrial motor controls, and high-voltage power supply monitoring requiring stable component supply and long-lifecycle support.

Supply support for AD629ANZ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD629 belongs to Analog Devices' precision difference amplifier product line, designed specifically for high common-mode voltage measurement in industrial, automotive, and energy infrastructure applications without galvanic isolation.

FAQ

What is the maximum common-mode voltage the AD629ANZ can handle continuously?

The AD629ANZ supports continuous operation at ±270 V common-mode voltage with ±15 V supplies, as specified in the Absolute Maximum Ratings table. It also withstands ±500 V common-mode transients for up to 10 seconds - a key differentiator from standard instrumentation amplifiers. This rating applies directly to the AD629ANZ in its 8-lead PDIP package and is validated across the full −40°C to +85°C temperature range.

Does the AD629ANZ require external resistors for unity-gain operation?

No, the AD629ANZ does not require external resistors for unity-gain operation. Its internal laser-trimmed resistor network (including 380 kΩ and 21.1 kΩ elements) is factory-configured to deliver precise G = 1 differential gain. External components are only needed for single-supply biasing (REF(+) and REF(−) tied to reference voltage) or output filtering - the core amplification function is fully self-contained within the AD629ANZ die.

Can the AD629ANZ be used with a single 12 V supply?

Yes, the AD629ANZ supports single-supply operation. When using a 12 V supply, REF(+) and REF(−) must be biased to a stable mid-rail voltage (e.g., 6 V) using a low-impedance source capable of sinking current. This shifts the output common-mode level, allowing the AD629ANZ to swing ±3 V around 6 V. Note that single-supply operation reduces the input common-mode range to approximately ±85 V, as calculated from the internal node constraints described in the AD629ANZ datasheet.

What is the purpose of Pin 8 (NC) on the AD629ANZ?

Pin 8 on the AD629ANZ is designated "No Connect" (NC) and is internally unconnected. It must remain unconnected in all PCB layouts - routing, soldering, or grounding Pin 8 degrades common-mode rejection ratio (CMRR) and may cause instability. This requirement is explicitly stated in the Pin Function Descriptions table and Functional Block Diagram of the AD629ANZ datasheet Rev. C.

How does the AD629ANZ compare to the INA117 in terms of input protection?

The AD629ANZ provides robust ±500 V common-mode and differential input protection for up to 10 seconds, whereas the INA117 lacks explicit transient ratings and requires external clamping diodes for voltages above ±35 V. This makes the AD629ANZ suitable for direct connection to high-voltage buses without additional protection circuitry - a verified advantage confirmed in Analog Devices' application notes and error budget analyses comparing AD629ANZ and INA117P in 200 V common-mode scenarios.