AD8639ARZ

Overview

The AD8639ARZ is a dual-channel, wide-bandwidth auto-zero operational amplifier manufactured by Analog Devices Inc. It features rail-to-rail output swing and operates on single supplies from 5 V to 16 V or dual supplies from ±2.5 V to ±8 V. Key electrical specifications include a maximum offset voltage of 9 μV, a maximum offset drift of 0.04 μV/°C, and a typical gain bandwidth product of 1.5 MHz. The device draws a maximum supply current of 1.3 mA per amplifier and offers high common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR). It is housed in an 8-lead MSOP package.

Feature Summary

• Utilizes a patented ping-pong auto-zero topology that combines chopping and auto-zeroing techniques to minimize low-frequency noise and digital switching artifacts without requiring external filtering capacitors.
• Provides rail-to-rail output swing capability, allowing the signal to utilize the full dynamic range between the supply rails to maximize signal-to-noise ratio.
• Delivers ultrahigh precision with extremely low input offset voltage and drift, ensuring stable performance across the extended industrial temperature range.

Applications

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

Procurement Notes

Verify the specific ordering suffix 'ARZ' against the manufacturer's official documentation to confirm the package type and temperature grade. Ensure compatibility with the required PCB footprint for the 8-lead MSOP configuration. Cross-reference the datasheet revision to validate all electrical parameters before finalizing procurement specifications.

Selection Notes

Select this component when high DC accuracy and low drift are critical requirements. The dual-channel architecture allows for cost-effective implementation in multi-sensor systems. Consider the 1.5 MHz bandwidth and slew rate for applications requiring moderate speed alongside high precision. Verify that the input common-mode voltage remains within the specified limits to prevent phase reversal.

Part Context

The AD8639 is part of the AD8638/AD8639 family of auto-zero amplifiers designed to offer zero-drift performance at a lower cost than traditional chopper-stabilized devices. While the AD8638 provides a single channel, the AD8639 integrates two identical channels into one package. This series is engineered to eliminate 1/f noise internally, making it suitable for high-resolution data acquisition systems.

Replacement Considerations

The AD8639ACPZ serves as a pin-compatible alternative utilizing an LFCSP package. For single-channel applications, the AD8638ARZ provides equivalent electrical characteristics in an SOIC package. Verify thermal resistance values and physical dimensions when substituting packages.

FAQ

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

No, the AD8639 utilizes an internal patented topology that eliminates the need for external capacitors typically required in other auto-zero or chopper-stabilized amplifiers.

What is the mechanism behind the low noise performance of the AD8639?

The device employs a ping-pong arrangement of auto-zeroing and chopping to reduce low-frequency noise and minimize noise energy at the clock frequencies, effectively eliminating 1/f noise internally.