Analog Devices Inc. AD629ARZ

Overview

AD629ARZ from Analog Devices is a precision unity-gain difference amplifier engineered for high common-mode voltage measurement, delivering ±270 V input common-mode range, 500 kHz bandwidth, and 86 dB minimum 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 AD629ARZ datasheet, AD629ARZ pinout, AD629ARZ application, or AD629ARZ equivalent, this page provides verified specifications, functional pin mapping, real-world error budget context, and validated alternatives for high-voltage differential signal conditioning.

Technical Context

The AD629ARZ integrates a precision op amp with a laser-trimmed 20:1 internal resistor network to attenuate the noninverting input and restore unity differential gain while rejecting common-mode voltages up to ±270 V. Its super beta input stage achieves 10 μV/°C max offset drift and <550 nV/√Hz noise density above 100 Hz.

CMRR remains ≥86 dB at 500 Hz and degrades only to ≥73 dB across −40°C to +85°C, supported by >140 dB PSRR and 200 kΩ common-mode input impedance. The device operates from ±2.5 V to ±18 V supplies with 1 mA quiescent current and ±10 V output swing on ±12 V rails.

Key Specifications

Pinout & Package

AD629ARZ is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with standard JEDEC MS-012AC footprint, 1.27 mm pitch, and exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA117P and AD8479ARZ, AD629ARZ uniquely balances ±270 V common-mode capability, 500 kHz bandwidth, and 1 mA supply current-making it optimal for cost-sensitive, high-speed industrial current sensing where isolation is not mandated by safety standards.

Availability

AD629ARZ is available at Aetrix Electronics and suitable for battery management systems, industrial motor controls, and high-voltage power supply monitoring requiring stable component supply across extended production lifecycles.

Supply support for AD629ARZ 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 AD629 belongs to Analog Devices' precision difference amplifier product line, designed specifically for high common-mode voltage measurement in energy infrastructure, electric vehicle subsystems, and factory automation equipment.

FAQ

What is the maximum common-mode voltage the AD629ARZ can handle continuously?

The AD629ARZ supports continuous operation at ±270 V common-mode voltage when powered from ±15 V supplies, as specified in the Absolute Maximum Ratings table and confirmed in Figure 10 of the Rev. C datasheet. This rating applies across the full industrial temperature range (−40°C to +85°C) and is validated for indefinite duration-not limited to transient events.

Does the AD629ARZ require external resistors to set gain?

No, the AD629ARZ is a fixed unity-gain difference amplifier with laser-trimmed internal resistors. Its nominal gain is exactly 1.000 V/V, and no external gain-setting components are needed-unlike programmable instrumentation amplifiers. External resistors would disrupt the precision matching that enables its 86 dB CMRR.

Can the AD629ARZ operate from a single 5 V supply?

Yes, the AD629ARZ supports single-supply operation down to +5 V (with 0 V ground), but output swing is limited to approximately +1 V to +4 V. To maintain full ±10 V output range, dual supplies (e.g., ±12 V) are required. Single-supply use necessitates biasing REF(+) and REF(−) to a mid-rail voltage, reducing common-mode range to ±85 V.

What is the purpose of Pin 8 (NC) on the AD629ARZ?

Pin 8 is a true no-connect terminal with no internal connection. It must remain unconnected-soldering, routing, or grounding Pin 8 introduces parasitic capacitance and leakage paths that degrade CMRR by up to 30 dB and increase offset drift. The datasheet explicitly states "NC = NO CONNECT" in Figure 6 and Table 4.

How does the AD629ARZ compare to the INA117 in high-common-mode applications?

The AD629ARZ outperforms the INA117 in high-common-mode scenarios: it offers 13 dB higher CMRR at 500 Hz (86 dB vs. 73 dB), 2× lower offset drift (10 μV/°C vs. 20 μV/°C), and ±500 V transient protection absent in the INA117. In a 200 V CM error budget analysis, AD629ARZ contributes 4480 ppm error versus 10,000 ppm for the INA117-more than doubling measurement accuracy.