Analog Devices Inc. AD629BNZ

Overview

AD629BNZ 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, 86 dB minimum CMRR at 500 Hz, 500 kHz bandwidth, and 10 μV/°C max offset drift. It serves as a direct replacement for INA117 in battery cell monitoring and motor control current sensing where galvanic isolation is unnecessary.

For engineers reviewing the AD629BNZ datasheet, AD629BNZ pinout, AD629BNZ application, or AD629BNZ equivalent, this page provides verified specifications, functional pin mapping, real-world use cases, and validated alternative options - all aligned with Rev. C datasheet performance across −40°C to +85°C.

Technical Context

The AD629BNZ implements a laser-trimmed resistor network (20× attenuation on +IN path, matched feedback) to achieve precise unity differential gain while rejecting up to ±270 V common-mode signals. Its internal super beta op amp delivers >20 million open-loop gain and >140 dB PSRR, enabling stable operation with ±2.5 V to ±18 V dual supplies.

Input protection withstands ±500 V common-mode and differential transients; output drives ±12.5 V into 2 kΩ with 1.7 V/μs slew rate and settles to 0.01% in 5 μs for common-mode steps. CMRR remains ≥82 dB over full temperature range and degrades only to 73 dB at 1 kHz under ±250 V dc conditions.

Key Specifications

Pinout & Package

AD629BNZ is supplied in an 8-lead PDIP (Plastic Dual In-line Package) with 0.3 inch body width and standard through-hole mounting. Pin 8 is NC (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, AD629BNZ offers the optimal balance of ±270 V CMV capability, 86 dB CMRR, 10 μV/°C drift, and 1 mA quiescent current - making it uniquely suited for cost-sensitive, high-accuracy battery and power supply monitoring where isolation is unnecessary.

Availability

AD629BNZ is available at Aetrix Electronics and suitable for high voltage current sensing, battery cell voltage monitoring, and motor control phase current sensing requiring stable component supply across industrial temperature grades.

Supply support for AD629BNZ 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 accurate high common-mode voltage measurement in power electronics, energy storage, and industrial control systems.

FAQ

What is the maximum common-mode voltage the AD629BNZ can handle continuously?

The AD629BNZ supports a continuous input common-mode voltage range of ±270 V when operated with ±15 V supplies, as specified in the Rev. C datasheet. Absolute maximum ratings allow ±300 V continuous and ±500 V for 10 seconds - but sustained operation above ±270 V may degrade accuracy or reliability. For designs targeting 200–250 V CMV, AD629BNZ provides guaranteed performance with margin.

Does the AD629BNZ require external resistors for unity gain configuration?

No, the AD629BNZ integrates all precision resistors internally - including the 20× attenuator on the +IN path and matched feedback network - so no external gain-setting components are needed for G = 1 operation. REF(−) and REF(+) must be tied to the same low-impedance ground point to maintain specified CMRR; adding external resistors disrupts laser-trimmed matching and degrades performance.

Can the AD629BNZ operate from a single 12 V supply?

Yes, the AD629BNZ supports single-supply operation: apply +12 V to Pin 7 (+VS) and ground Pin 4 (−VS), then bias REF(+) and REF(−) to a mid-rail voltage (e.g., 6 V) to establish output swing centered at that reference. Note that this reduces the usable common-mode input range to approximately ±85 V to −75 V (for 10 V supply) - consult Figure 33 and associated equations in the Rev. C datasheet for exact limits.

What is the purpose of Pin 8 (NC) on the AD629BNZ?

Pin 8 is designated NC (No Connect) and contains no internal connection. It must remain unconnected - neither grounded nor routed - as bonding or loading this pin introduces parasitic capacitance and disturbs internal node symmetry, directly degrading common-mode rejection ratio. The Rev. C datasheet explicitly states "Do not connect to this pin" in Table 4 and Figure 6.

How does the AD629BNZ compare to the AD629ANZ in terms of performance?

The AD629BNZ specifies tighter performance limits than the AD629ANZ: offset drift is 10 μV/°C max (vs. 20 μV/°C for AD629ANZ), gain nonlinearity is 3 ppm max (vs. 4 ppm), and CMRR is 86 dB min at 500 Hz (vs. 77 dB). Both share identical pinout, package, and temperature range (−40°C to +85°C), but AD629BNZ is selected for applications demanding highest DC precision in high-CMV environments.