AD8684ARZ-REEL

Overview

The AD8684ARZ-REEL is a quad, low power, high speed JFET input operational amplifier manufactured by Analog Devices Inc. It features a maximum supply current of 250 μA per amplifier and a typical slew rate of 9 V/μs. The device offers a gain bandwidth product of 3.5 MHz and a maximum offset voltage of 1 mV at 25°C. Input bias current is limited to 20 pA maximum at 25°C, rising to 125 pA over the operating temperature range. Common-mode rejection ratio is typically 90 dB. It supports dual supplies from ±4.5 V to ±18 V or single supplies from 9 V to 36 V. The component is housed in a 14-Lead SOIC_N package.

Feature Summary

• JFET input stage ensures extremely low input bias current for high source impedance applications
• Unity-gain stable with fast settling time suitable for precision signal processing
• Optimized for high speed performance while maintaining low quiescent power consumption
• Common-mode input range extends to the positive supply rail

Applications

• Portable telecommunications equipment
• Low power industrial and instrumentation systems
• Active and precision filters
• Strain gauge amplifiers
• Supply current monitoring circuits

Procurement Notes

Verify that the ordering suffix REEL corresponds to the tape and reel packaging format specified in the manufacturer's ordering guide. Confirm the RoHS compliant status indicated by the Z suffix. Ensure the 14-Lead SOIC_N package option matches the required footprint for the design. Cross-reference the specific part number against the latest datasheet revision B to confirm electrical characteristics have not changed.

Selection Notes

Select this component when a quad configuration is required alongside low power constraints and high speed requirements. The JFET input architecture is preferred over CMOS for lower bias currents in high impedance sensor interfaces. Verify that the 3.5 MHz bandwidth and 9 V/μs slew rate meet the dynamic signal requirements. Consider the phase inversion behavior if input signals exceed the common-mode range near the negative rail.

Part Context

This device belongs to the AD8682/AD8684 family of low power, high speed JFET operational amplifiers. The AD8684 provides four independent amplifiers within a single package, whereas the AD8682 provides two. Both share identical electrical specifications and are designed for portable, battery-powered applications requiring precision and speed.

Replacement Considerations

The AD8682 serves as the dual-channel equivalent within the same family. Other quad JFET op-amps may be considered if pin compatibility is not required, but direct substitutes must match the 14-Lead SOIC_N package and similar electrical parameters.

FAQ

Does the AD8684 experience phase inversion?

Yes, most JFET input amplifiers invert the phase if either input exceeds the common-mode range. For the AD8684, a negative signal exceeding 11 V causes phase inversion due to input stage saturation.

What is the input common-mode voltage range?

The guaranteed common-mode range is -11 V to +15 V when supplied with ±15 V, which includes the positive supply rail.

How does the input bias current vary with temperature?

The input bias current is typically a few picoamps at 25°C and increases with temperature, reaching a maximum of 125 pA over the full operating temperature range of -40°C to +85°C.