AD8639ARMZ-R7

Overview

The AD8639ARMZ-R7 is a dual-channel, auto-zero operational amplifier manufactured by Analog Devices Inc. It features rail-to-rail output swing and operates on a single supply of 5 V to 16 V or dual supplies of ±2.5 V to ±8 V. Key electrical parameters include a maximum offset voltage of 9 μV, an input bias current of up to 250 pA at high temperatures, and a gain-bandwidth product of 1.5 MHz. The device provides a typical large signal voltage gain of 147 dB and a power supply rejection ratio of 143 dB. It is housed in an 8-lead MSOP package and supports an operating temperature range from -40°C to +125°C.

Feature Summary

• Utilizes a patented auto-zero topology to achieve extremely low offset voltage and drift without requiring external capacitors.
• Features rail-to-rail output swing capability to maximize signal-to-noise ratio across the full supply voltage range.
• Incorporates a ping-pong arrangement of auto-zeroing and chopping to minimize low-frequency noise and digital switching artifacts.

Applications

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

Procurement Notes

Verify the specific suffix R7 indicates reel packaging when sourcing. Confirm automotive qualification status if required for the application, as standard versions may differ from qualified grades. Ensure the MSOP-8 package dimensions match the PCB footprint requirements. Cross-reference the manufacturer part number with authorized distributors to validate authenticity and revision level.

Selection Notes

Select this component for applications demanding high DC precision and low drift over wide temperature ranges. The dual-channel configuration allows for cost-effective implementation of differential sensor interfaces. Consider the 1.5 MHz bandwidth for systems requiring moderate speed alongside high accuracy. Evaluate the 8-lead MSOP package constraints regarding thermal dissipation and board space availability.

Part Context

The AD8639 is the dual-channel counterpart to the single-channel AD8638 within Analog Devices' auto-zero amplifier family. Both share identical core specifications, including offset voltage, drift, and noise characteristics. The AD8639 specifically integrates two independent amplifiers into a compact 8-lead MSOP package, facilitating space-constrained designs requiring multiple precision signal conditioning stages.

Replacement Considerations

The AD8638 serves as the single-channel equivalent within the same series. For automotive-grade requirements, verify specific qualified part numbers listed in the manufacturer's ordering guide, as standard commercial parts may not meet those specific standards.

FAQ

Does the AD8639 require external capacitors for its auto-zero function?

No, the AD8639 utilizes a proprietary topology that eliminates the need for external capacitors to maintain low offset voltage and drift.

What is the input voltage range limitation for the AD8639?

The inputs are not rail-to-rail; they must be maintained within the specified common-mode range, typically requiring at least 2 V below the positive supply to prevent output phase reversal.