Analog Devices Inc./Maxim Integrated MAX4251ESA+

Overview

MAX4251ESA+ from Analog Devices is a single, rail-to-rail output, low-noise, low-distortion operational amplifier optimized for single-supply operation from 2.4V to 5.5V. It delivers 400µA quiescent current per amplifier, 0.0002% THD at 1kHz, 7.9nV/√Hz input voltage-noise density at 30kHz, and unity-gain stability with 3MHz gain-bandwidth product - making it ideal for precision ADC buffering in portable instrumentation.

For engineers reviewing the MAX4251ESA+ datasheet, MAX4251ESA+ pinout, MAX4251ESA+ application, or MAX4251ESA+ equivalent, key selection criteria include its shutdown capability (0.5µA), rail-to-rail output swing within 8mV of rails (10kΩ load), ±1pA input bias current, 70µV max input offset voltage, and SO-8 package compatibility with space-constrained industrial sensor interfaces.

Technical Context

The MAX4251ESA+ belongs to the MAX4249–MAX4257 family of single-supply op amps featuring true rail-to-rail output stages and ground-sensing inputs (common-mode range includes VSS). Its internal compensation ensures unity-gain stability, enabling use in low-gain configurations without external compensation.

It integrates a low-power shutdown mode (SHDN pin) that disables the amplifier and places the output in high-impedance state while reducing supply current to 0.5µA. The device maintains DC accuracy driving 1kΩ loads and handles up to 400pF capacitive loads without oscillation.

Key Specifications

Pinout & Package

MAX4251ESA+ is housed in an 8-pin SOIC (SO-8) package with standard JEDEC MS-012AC outline. Pin 1 is located at the top-left corner adjacent to the index notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, low-power op amp applications.

Compared with OPA333AIDR and AD8605ARZ, the MAX4251ESA+ uniquely balances sub-1µA shutdown current, 3MHz GBW, and 7.9nV/√Hz noise in an SO-8 package - making it optimal for battery-powered precision sensing where both dynamic performance and ultra-low standby power are mandatory.

Availability

MAX4251ESA+ is available at Aetrix Electronics and suitable for portable medical sensors, industrial strain gauge interfaces, ADC input buffers, and battery-powered data loggers requiring stable component supply across extended production lifecycles.

Supply support for MAX4251ESA+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The MAX4249–MAX4257 product line was designed specifically for low-noise, low-distortion, single-supply signal conditioning in portable and precision measurement systems - emphasizing rail-to-rail operation, ground-sensing inputs, and micropower shutdown.

FAQ

What is the maximum capacitive load the MAX4251ESA+ can drive without external compensation?

The MAX4251ESA+ remains stable driving capacitive loads up to 400pF without requiring external isolation resistors or feed-forward compensation. This capability simplifies design when interfacing directly with ADC input capacitance or long PCB traces, avoiding added components and potential phase-margin degradation. For loads exceeding 400pF, a series isolation resistor (e.g., 150Ω for 1000pF) restores stability while maintaining signal fidelity in the MAX4251ESA+ signal path.

Does the MAX4251ESA+ support true rail-to-rail input operation?

The MAX4251ESA+ does not support rail-to-rail input - its input common-mode voltage range extends from VSS − 0.2V to VDD − 1.1V, meaning it senses down to 200mV below ground but only up to 1.1V below VDD. However, it does provide true rail-to-rail output swing, delivering signals within 8mV of both supply rails under 10kΩ load. This makes the MAX4251ESA+ ideal for ground-referenced sensor interfaces where input common-mode is near VSS, but full output swing is required.

What is the typical input voltage-noise density of the MAX4251ESA+ at 1kHz?

The typical input voltage-noise density of the MAX4251ESA+ at 1kHz is 8.9nV/√Hz, as specified in the Electrical Characteristics table. This value reflects the device's ultra-low-noise performance critical for preserving signal-to-noise ratio in high-resolution sensor front-ends. At higher frequencies (e.g., 30kHz), the noise density drops further to 7.9nV/√Hz due to reduced flicker noise contribution - a key advantage of the MAX4251ESA+ in wideband applications such as audio preamplifiers or broadband instrumentation.

Can the MAX4251ESA+ operate from a 2.4V single supply?

Yes, the MAX4251ESA+ is fully specified to operate from a single 2.4V supply, with guaranteed performance across the full −40°C to +85°C temperature range. At 2.4V, it maintains rail-to-rail output swing, 400µA quiescent current, and 0.0002% THD+N - enabling use in energy-harvesting systems and ultra-low-voltage portable devices. Its ability to function reliably at this minimum supply voltage distinguishes the MAX4251ESA+ from many competing op amps that require ≥2.7V or ≥3.0V operation.

How does the shutdown feature of the MAX4251ESA+ affect output state?

When the SHDN pin of the MAX4251ESA+ is pulled low (≤0.2×VDD), the amplifier enters shutdown mode, reducing supply current to 0.5µA and placing the output in a high-impedance (tri-state) condition. This prevents loading of downstream circuitry and eliminates DC path errors during sleep cycles. The output does not clamp to VDD or VSS - it floats - so external pull-up/down resistors may be needed if a defined voltage level is required during shutdown. Recovery time to full operation is 8µs, as measured from SHDN rising edge to output settling within 0.1%.