AD8643ARZ-REEL7

Overview

The AD8643ARZ-REEL7 is a quad, low-power, precision JFET input operational amplifier featuring rail-to-rail output capability. It operates on single supplies from 5 V to 26 V or dual supplies from ±2.5 V to ±13 V. Key electrical characteristics include a maximum supply current of 250 µA per amplifier, a maximum input bias current of 1 pA, and a maximum offset voltage of 750 µV. The device offers a gain bandwidth product of 2.5 MHz and a slew rate of 2 V/µs at 5 V supply. It is unity-gain stable, exhibits no phase reversal, and maintains stability with capacitive loads exceeding 500 pF. The component is fully specified over the extended industrial temperature range of −40°C to +125°C.

Feature Summary

• JFET input stage providing extremely low input bias current for high-impedance signal sources.
• Rail-to-rail output swing enabling full dynamic range utilization in single-supply systems.
• Unity-gain stability with guaranteed performance under capacitive loads greater than 500 pF.
• No phase reversal behavior ensures reliable operation when input common-mode voltage approaches negative supply rails.

Applications

• Photodiode amplifiers
• Precision current sensing
• Battery management systems
• Industrial controls
• ATE reference level drivers

Procurement Notes

Verify that the ordering suffix REEL7 corresponds to the specific tape-and-reel packaging configuration required for automated assembly processes. Confirm the package option matches the 14-Lead Standard Small Outline Package (R-14) as defined in the manufacturer's ordering guide. Ensure the RoHS compliant status indicated by the Z suffix aligns with environmental compliance requirements for the target production environment.

Selection Notes

Select this component when designing circuits requiring four independent amplifiers with low power consumption and high input impedance. The quad configuration reduces board space compared to using individual single or dual amplifiers. Consider the 14-lead SOIC package for applications where surface-mount footprint constraints allow for wider spacing. Verify that the 2.5 MHz gain bandwidth product meets the frequency response requirements of the intended signal processing chain.

Part Context

This part belongs to the AD864x family of low power, precision JFET amplifiers, which includes the single-channel AD8641 and dual-channel AD8642 variants. The AD8643 specifically provides four amplifiers in one package, sharing identical electrical specifications and pinout logic across channels. All members of this series utilize the same underlying JFET input technology and offer similar rail-to-rail output capabilities and low noise characteristics.

Replacement Considerations

Direct functional substitutes within the same family include the AD8641ARZ-REEL7 and AD8642ARZ-REEL7, though these offer different channel counts. Cross-family replacements must be evaluated based on matching JFET input bias currents, rail-to-rail output swing, and supply voltage ranges. Any substitute must maintain compatibility with the 14-lead SOIC footprint if physical interchangeability is required without PCB redesign.

FAQ

Does the AD8643 exhibit phase reversal when the input common-mode voltage reaches the negative supply rail?

No, the datasheet explicitly states that the AD8643 features no phase reversal, ensuring stable operation even when the input common-mode voltage approaches the negative supply rail.

What is the maximum capacitive load the AD8643 can drive while remaining stable?

The outputs remain stable with capacitive loads of more than 500 pF, allowing direct driving of significant cable capacitance or sample-and-hold inputs without additional compensation components.

How does the input bias current vary across the operating temperature range?

At 25°C, the input bias current is typically 0.25 pA with a maximum of 1 pA. Over the extended industrial temperature range of −40°C to +125°C, the maximum input bias current increases to 180 pA to 260 pA depending on the supply voltage configuration.