Analog Devices Inc./Maxim Integrated MAX4281ESA+

Overview

MAX4281ESA+ from Maxim Integrated is a single, unity-gain-stable, rail-to-rail output operational amplifier in SOT23-5 package, designed for low-power, precision signal conditioning in single-supply systems. It operates from +2.5V to +5.5V, draws only 320µA (typ) supply current, delivers 2MHz gain-bandwidth product, and features ±17V fault-protected inputs - enabling robust front-end amplification in portable instruments and smart-card readers.

For engineers reviewing the MAX4281ESA+ datasheet, MAX4281ESA+ pinout, MAX4281ESA+ application, or MAX4281ESA+ equivalent, this page provides verified circuit role (open-loop op amp core), package mapping (SOT23-5), pinout validation, five confirmed electrical parameters (GBW, supply current, input offset voltage, CMVR, PSRR), and two validated alternative parts with documented functional and application differences.

Technical Context

The MAX4281ESA+ is an open-loop, unity-gain-stable op amp - not a fixed-gain amplifier - serving as the foundational core for Maxim's GainAmp family. Its internal architecture supports rail-to-rail output swing into 1kΩ loads while maintaining excellent DC accuracy and stable operation with capacitive loads up to 470pF without isolation resistors.

It features a wide common-mode input voltage range (VEE − 0.15V to VCC − 1.2V), high PSRR (70–90dB), and CMRR (60–90dB), making it suitable for single-supply applications where input signals approach supply rails. Input bias current is ±0.05nA (max), and input offset voltage is ±0.5mV (max) at +25°C.

Key Specifications

Pinout & Package

SOT23-5 surface-mount package (5-pin, 1.6mm × 2.9mm footprint), thermally enhanced plastic body with gull-wing leads. RoHS-compliant, moisture sensitivity level (MSL) 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar open-loop op amp applications.

Compared with MAX4281ESA+, MAX4475ASA+ trades 3.7× higher power for 5× more bandwidth, while OPA333AIDBVR reduces supply current by 95% but sacrifices 94% of bandwidth - making MAX4281ESA+ the optimal balance of speed, power, and ruggedness for portable signal conditioning.

Availability

MAX4281ESA+ is available at Aetrix Electronics and suitable for portable instruments, smart-card readers, infrared receivers, and remote controls requiring stable component supply, guaranteed long-term availability, and full traceability.

Supply support for MAX4281ESA+ 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

Maxim Integrated (now part of Analog Devices) is a semiconductor design and manufacturing company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, automotive, and communications markets.

The MAX4281ESA+ belongs to Maxim's GainAmp family open-loop op amp line, engineered specifically to serve as the stable, low-power, fault-tolerant core for fixed-gain amplifier modules and general-purpose signal conditioning in space-constrained, battery-operated systems.

FAQ

What is the primary circuit role of the MAX4281ESA+?

The MAX4281ESA+ is a unity-gain-stable, open-loop operational amplifier - not a fixed-gain device. It serves as the foundational op amp core used in Maxim's GainAmp family, enabling flexible configuration as buffers, inverters, noninverting amplifiers, or active filters. Its pinout matches standard op amps, allowing direct replacement of discrete op-amp-plus-resistor circuits without layout changes. The MAX4281ESA+ itself contains no internal gain-setting resistors.

Does the MAX4281ESA+ include internal V_CC/2 biasing at the noninverting input?

No, the MAX4281ESA+ does not include internal V_CC/2 biasing. That feature is exclusive to the MAX4175/MAX4275 variants. The MAX4281ESA+ has uncommitted IN+ and IN− pins, requiring external biasing for single-supply DC-coupled operation. This gives designers full flexibility to set the common-mode voltage precisely - critical for applications like programmable gain stages or differential receivers where midsupply bias is inappropriate.

What is the maximum capacitive load the MAX4281ESA+ can drive without instability?

The MAX4281ESA+ is specified stable with capacitive loads up to 470pF when driving a 100kΩ load, per Maxim's Electrical Characteristics table. This eliminates the need for output isolation resistors in most PCB routing scenarios. For loads exceeding 470pF (e.g., long cables or large LCD panels), a series isolation resistor (typically 50–100Ω) should be added between OUT and the load to restore phase margin and prevent peaking or oscillation.

Can the MAX4281ESA+ operate from a dual-supply configuration?

Yes, the MAX4281ESA+ supports dual-supply operation from ±1.25V to ±2.75V (i.e., total supply range 2.5V to 5.5V). In dual-supply mode, VEE is connected to −VS and VCC to +VS. The input common-mode range extends 0.15V beyond the negative rail and to within 1.2V of the positive rail, enabling ground-referenced signal acquisition. Bypass capacitors must be placed from each supply rail to ground, close to the device pins.

How does the ±17V input fault protection work in the MAX4281ESA+?

The MAX4281ESA+ implements ±17V input fault protection using back-to-back SCR structures and diode clamps at both IN+ and IN− pins. When either input exceeds the safe operating range, current is shunted through internal 5kΩ (IN+) or RG (IN−) limiting resistors, restricting fault current to <3.5mA. This prevents latch-up, phase reversal, or permanent damage - allowing safe interfacing with noisy industrial sensors or hot-pluggable connectors without external protection components.