Analog Devices Inc. ADA4638-1ARZ-R7

Overview

ADA4638-1ARZ-R7 from Analog Devices is a single-channel, high-voltage zero-drift operational amplifier with rail-to-rail output, 4 μV max offset voltage, 0.05 μV/°C max drift, and 130 dB min CMRR. It operates from 4.5 V to 30 V single supply or ±2.25 V to ±15 V dual supply, consuming ≤0.95 mA, and is used in precision sensor front-ends such as thermocouple and strain gage amplifiers.

For engineers reviewing the ADA4638-1ARZ-R7 datasheet, ADA4638-1ARZ-R7 pinout, ADA4638-1ARZ-R7 application, or ADA4638-1ARZ-R7 equivalent, this page delivers verified specifications, SOIC-8 package mapping, real-world use scenarios in medical instrumentation and electronic weigh scales, and two validated alternative op-amps with documented functional trade-offs.

Technical Context

The ADA4638-1ARZ-R7 implements a patented dual-stage auto-zeroing and chopping architecture with 8 kHz auto-zero and 16 kHz chop frequencies, eliminating 1/f noise while minimizing switching artifacts. Its input stage uses transconductance amplifiers A1/A2 with nulling amplifiers A3/A4 and storage capacitors C1–C4 to dynamically correct offset in alternating phases.

It features input common-mode range extending to the negative rail, no output phase reversal under overdrive, and internal ESD diodes requiring external current limiting if inputs exceed supply rails. The output drives ≥10 kΩ loads to within 60 mV of rails at ±5 V, supporting high SNR in low-frequency DC-coupled signal chains.

Key Specifications

Pinout & Package

ADA4638-1ARZ-R7 is supplied in an 8-lead SOIC package (SOIC_N) with exposed pad connected to V– per datasheet recommendation. Pin 1 is NC (no connect), pins 2 and 3 are inverting and non-inverting inputs, pin 4 is V–, pin 6 is output, and pin 7 is V+.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision op-amp applications.

Compared with AD8628ARZ and ADA4528-1ARMZ, the ADA4638-1ARZ-R7 uniquely balances 30 V operation, sub-5 μV offset, and 0.05 μV/°C drift-making it the only option for high-voltage, high-accuracy DC signal chains where supply headroom and long-term calibration stability are co-constrained.

Availability

ADA4638-1ARZ-R7 is available at Aetrix Electronics and suitable for electronic weigh scale manufacturing, medical device production, and industrial pressure sensor module assembly requiring stable component supply across extended temperature and voltage ranges.

Supply support for ADA4638-1ARZ-R7 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 ADA4638-1ARZ-R7 belongs to Analog Devices' zero-drift op-amp portfolio targeting ultra-precision DC-coupled applications-including sensor signal conditioning, medical diagnostics, and test equipment-where offset, drift, and low-frequency noise must be minimized without sacrificing supply flexibility.

FAQ

What is the maximum supply voltage rating for the ADA4638-1ARZ-R7?

The ADA4638-1ARZ-R7 has an absolute maximum supply voltage of 33 V. It is fully specified for continuous operation from 4.5 V to 30 V single supply or ±2.25 V to ±15 V dual supplies. Exceeding 33 V risks permanent damage per Absolute Maximum Ratings table on page 6 of the Rev. 0 datasheet.

Does the ADA4638-1ARZ-R7 require external components for stability with capacitive loads?

Yes-the ADA4638-1ARZ-R7 exhibits overshoot and potential ringing when driving >100 pF directly. Figure 39 shows >20% overshoot at 1000 pF. For loads >100 pF, Analog Devices recommends adding a series resistor (typically 10–100 Ω) between the output and capacitive load to isolate the amplifier's output impedance from the capacitance.

How does the ADA4638-1ARZ-R7 handle input overvoltage conditions?

The ADA4638-1ARZ-R7 includes internal ESD diodes from each input to V+ and V–. If either input exceeds the supply rails, these diodes forward-bias and conduct. To prevent damage, external series resistors must limit input current to ≤10 mA. This is mandatory for applications with transient overvoltage exposure, such as industrial sensor nodes.

Is the ADA4638-1ARZ-R7 pin-compatible with other zero-drift op-amps in SOIC-8 packages?

No-ADA4638-1ARZ-R7 is not pin-compatible with AD8628ARZ or ADA4528-1ARMZ. While all three use SOIC-8, ADA4638-1ARZ-R7 places NC on pins 1 and 5, whereas AD8628ARZ uses pin 1 for shutdown and ADA4528-1ARMZ assigns pin 5 to V–. PCB layout must be dedicated to ADA4638-1ARZ-R7.

What is the typical closed-loop bandwidth of the ADA4638-1ARZ-R7 at unity gain?

At unity gain (AV = +1), the ADA4638-1ARZ-R7 achieves a −3 dB closed-loop bandwidth of 2.5 MHz under 30 V operation (Table 2), 1.9 MHz at 10 V (Table 3), and 1.8 MHz at 5 V (Table 4). Bandwidth scales with supply voltage due to increased slew rate headroom and internal bias current.