MAX4238ASA

Instrumentation, Op Amps, Buffer Amps Overview

The MAX4238ASA+ is a single-channel, ultra-high precision amplifier from Analog Devices/Maxim Integrated. It features an input offset voltage of 0.1µV typical and 2µV maximum at +25°C, with a drift of 10nV/°C. The device operates on a single supply ranging from 2.7V to 5.5V, consuming 600µA in active mode and 0.1µA in shutdown. Key electrical parameters include a gain-bandwidth product of 1MHz, a slew rate of 350mV/µs, and an input bias current of 1pA. It offers rail-to-rail output capability and high common-mode rejection ratio (CMRR) and power-supply rejection ratio (PSRR) values of 140dB.

Instrumentation, Op Amps, Buffer Amps Feature Summary

• Utilizes patented autocorrelating zeroing techniques to eliminate DC offset and low-frequency noise.
• Features a ground-sensing input allowing operation with signals referenced to the negative supply rail.
• Includes an active-low shutdown mode that significantly reduces quiescent current consumption.

Instrumentation, Op Amps, Buffer Amps Applications

• Thermocouple signal conditioning
• Strain gauge interface circuits
• Electronic scales
• Medical instrumentation
• High-precision instrumentation amplifiers

Instrumentation, Op Amps, Buffer Amps Procurement Notes

Verify the specific package suffix against the manufacturer's ordering guide to ensure correct pinout and thermal characteristics. Confirm RoHS compliance status as indicated by the '+' symbol in the part number. Check for automotive qualification requirements if the application demands AEC-Q100 standards, which may require a different suffix variant.

Instrumentation, Op Amps, Buffer Amps Selection Notes

Select the MAX4238ASA+ when unity-gain stability is required for low-noise, high-precision applications. This model is distinct from the decompensated MAX4239, which requires a minimum closed-loop gain of 10V/V. Ensure the design accounts for the maximum stable gain limits specified in the datasheet to maintain phase margin and prevent oscillation.

Instrumentation, Op Amps, Buffer Amps Part Context

This component belongs to the MAX4238/MAX4239 family of ultra-low offset and drift precision amplifiers. These devices are designed for sensor interfaces where DC accuracy is critical. The family utilizes BiCMOS process technology and employs autozeroing to cancel 1/f noise and long-term drift, making them suitable for demanding measurement environments.

Instrumentation, Op Amps, Buffer Amps Replacement Considerations

The MAX4239ASA+ serves as a functional substitute within the same package but requires a minimum closed-loop gain of 10V/V due to its decompensated nature. Direct replacement without adjusting circuit gain settings will result in instability. Verify that the system gain configuration meets the stability requirements of the alternative part.

Instrumentation, Op Amps, Buffer Amps FAQ

How does the MAX4238 handle low-frequency noise?

The device uses a patented autocorrelating zeroing technique that treats 1/f noise as a slow-varying offset error, inherently canceling it to achieve ultra-low noise performance.

What is the function of the SHDN pin?

The SHDN pin controls the shutdown mode. Pulling it low stops the internal clock and places the output in a high-impedance state, reducing supply current to 0.1µA. Connecting it to VCC enables normal operation.