AD8638ARJZ-R2

Overview

The AD8638ARJZ-R2 is a single-channel, precision auto-zero operational amplifier manufactured by Analog Devices Inc. It features rail-to-rail output swing and operates on a single supply from 5 V to 16 V or dual supplies of ±2.5 V to ±8 V. The device utilizes a patented auto-zero topology to achieve extremely low offset voltage (9 μV maximum) and drift (0.04 μV/°C maximum). Key electrical parameters include a gain bandwidth product of 1.5 MHz, a slew rate of 2 V/μs at 16 V, and a maximum input bias current of 40 pA. It offers high common-mode rejection ratio (133 dB typical) and power supply rejection ratio (143 dB typical), with a supply current of 1.3 mA maximum.

Feature Summary

• Patented auto-zeroing topology eliminates 1/f noise and maintains low offset voltage over temperature and time without external capacitors.
• Rail-to-rail output swing maximizes signal-to-noise ratio by utilizing the full dynamic range between supply rails.
• Very low input bias current minimizes errors when interfacing with high-impedance sensors.
• Fast overload recovery time ensures rapid stabilization after saturation events.

Applications

• Pressure and position sensors
• Strain gage amplifiers
• Medical instrumentation
• Thermocouple amplifiers
• Precision current sensing

Procurement Notes

Verify the specific package type associated with the ARJZ suffix against official documentation before procurement. Confirm that the R2 suffix corresponds to the correct reel quantity and packaging format required for your assembly process. Ensure compatibility with the intended operating temperature range of -40°C to +125°C.

Selection Notes

Select this component for applications requiring high DC precision and low drift in a compact SOT-23 package. It is suitable where low noise and wide bandwidth are critical alongside ultra-low offset. Consider the rail-to-rail output capability if maximizing dynamic range is necessary. Verify input voltage constraints to prevent phase reversal.

Part Context

The AD8638 is part of the AD8638/AD8639 family of wide bandwidth, auto-zero amplifiers. While the AD8639 provides dual channels, the AD8638 offers a single channel configuration. This series combines the benefits of zero-drift amplifiers with lower cost and reduced digital switching noise compared to traditional chopper-stabilized designs.

Replacement Considerations

Check for AD8638 variants with different package options such as SOIC if pin count or footprint requirements differ. Verify if automotive qualified versions like the AD8639 are needed for specific industry standards.

FAQ

Does the AD8638 have rail-to-rail input capability?

No, the AD8638 does not have rail-to-rail inputs. Care must be taken to ensure the input common-mode voltage remains within the specified range to avoid output phase reversal.

How does the AD8638 handle 1/f noise?

The internal auto-zeroing mechanism effectively eliminates 1/f noise, significantly reducing output errors in DC-coupled measurements.