AT8557/TR

Overview

The AT8557/TR is a zero-drift, rail-to-rail input/output CMOS operational amplifier manufactured by Analog Technologies. It utilizes auto-zero techniques to achieve an offset voltage of 20µV (typical) and 50µV (maximum), with an input offset drift of 0.03µV/°C (maximum). The device features a gain bandwidth product of 4.3MHz and a slew rate of 2.5V/µs. It operates on a supply voltage range of +2.7V to +5.5V, consuming 650µA per amplifier. Key specifications include a common-mode rejection ratio and power supply rejection ratio of ≥120dB, low noise of 0.93µVP-P from 0.01Hz to 10Hz, and an overload recovery time of 1µs.

Feature Summary

• Auto-zero technology provides ultralow offset voltage and near-zero drift over time and temperature.
• Rail-to-rail input and output capabilities ensure maximum dynamic range operation.
• High precision performance characterized by high gain, CMRR, and PSRR exceeding 120dB.
• Robust design includes integrated RFI/EMI rejection filters and high electrostatic discharge protection.

Applications

• Temperature and pressure sensor amplification
• Weight scale and strain gage signal conditioning
• Medical and industrial instrumentation systems
• Precision current sensing circuits

Procurement Notes

Verify the specific package suffix corresponding to the required footprint, as the AT8557 family supports SOT23-5, MSOP-8, and SOIC-8 configurations. Confirm that the selected variant meets the extended industrial temperature range requirements of −40°C to +125°C for the intended application environment. Ensure proper PCB layout practices, including the use of 0.1µF bypass capacitors placed closely to the supply pins, are implemented to maintain specified performance levels.

Selection Notes

Select the AT8557 when ultra-low offset voltage and minimal drift are critical for maintaining accuracy in low-frequency or DC applications. The device is suitable for designs requiring rail-to-rail signal swing within a single supply voltage range of 2.7V to 5.5V. Consider this component for space-constrained layouts due to its availability in small surface-mount packages while maintaining high precision characteristics comparable to higher-cost alternatives.

Part Context

The AT8557 is positioned as a drop-in replacement for the AD8557, offering upgraded performance metrics such as a higher gain bandwidth product and slew rate. Manufactured by Analog Technologies, it targets cost-sensitive markets requiring high-precision analog signal processing without compromising on electrical specifications or reliability standards defined for industrial and automotive environments.

Replacement Considerations

The datasheet explicitly identifies the AT8557 as an upgraded drop-in replacement for the AD8557. Designers should verify pin compatibility and thermal characteristics when transitioning between these specific part numbers to ensure seamless integration into existing hardware architectures.

FAQ

Does the AT8557 require external capacitors for stability?

No external capacitors are required for stability as the device is unity-gain stable and features integrated RFI/EMI rejection filters.

What is the input bias current specification for the AT8557?

The input bias current is specified at a maximum of 50pA over the operating temperature range.