Analog Devices Inc./Maxim Integrated MAX4491AKA+T

Overview

MAX4491AKA+T from Maxim Integrated is a single-channel, rail-to-rail input/output CMOS operational amplifier in SOT23-5 package, designed for precision low-voltage signal conditioning. It operates from 2.7V to 5.5V single supply, delivers 10MHz gain-bandwidth product, 10V/µs slew rate, and drives 2kΩ loads within 55mV of either rail - ideal for high-side current sensing in automotive-grade battery monitoring systems.

For engineers reviewing the MAX4491AKA+T datasheet, MAX4491AKA+T pinout, MAX4491AKA+T application, or MAX4491AKA+T equivalent, key selection criteria include capacitive-load stability up to 300pF, ±50mA short-circuit output current, 50pA input bias current, and guaranteed operation across –40°C to +125°C for under-hood sensor interfaces and portable medical devices.

Technical Context

The MAX4491AKA+T employs parallel N- and P-channel differential input stages enabling true rail-to-rail common-mode input range (VSS to VDD), with active switching between input pairs near VSS + 1.2V and VDD – 1.2V. Its class-AB push-pull output stage achieves <55mV output swing into 2kΩ at full temperature range.

It maintains unity-gain stability with capacitive loads ≤300pF without external compensation, supported by 60° phase margin and 10dB gain margin at 10MHz. Input capacitance is 5pF, requiring gain-setting resistor networks <3kΩ for optimal AC stability in inverting configurations.

Key Specifications

Pinout & Package

SOT23-5 package: ultra-compact surface-mount outline with 0.95mm pitch, 2.9mm × 1.6mm footprint, and thermal pad-less construction suitable for space-constrained portable and automotive modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar rail-to-rail op amp applications.

Compared with TSV911ILT and LMV931MG/NOPB, the MAX4491AKA+T uniquely combines automotive temperature qualification, 10MHz bandwidth, 300pF capacitive-load drive, and SOT23-5 footprint - making it the only drop-in solution for space-constrained, high-reliability current-sense and envelope-tracking circuits.

Availability

MAX4491AKA+T is available at Aetrix Electronics and suitable for battery-powered instrumentation, high-side current sensing, audio signal conditioning, and RF power amplifier control requiring stable component supply across automotive and industrial production cycles.

Supply support for MAX4491AKA+T 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.

The MAX4490/MAX4491/MAX4492 family was engineered specifically for low-voltage, rail-to-rail signal conditioning in space- and power-constrained systems - targeting automotive sensor interfaces, portable medical devices, and battery-operated test equipment.

FAQ

What is the maximum capacitive load the MAX4491AKA+T can drive without oscillation?

The MAX4491AKA+T is unity-gain stable with capacitive loads up to 300pF, as verified in the datasheet's Typical Operating Characteristics (Figure 4 and Capacitive-Load Stability chart). This applies to both inverting and noninverting configurations with resistive loads ≥100kΩ. For loads >300pF, an isolation resistor (e.g., 10Ω) in series with OUT is recommended - though this introduces gain error that must be calibrated in the MAX4491AKA+T system design.

Does the MAX4491AKA+T support dual-supply operation?

Yes, the MAX4491AKA+T supports dual-supply operation from ±1.35V to ±2.75V, per the Absolute Maximum Ratings and Electrical Characteristics tables. In dual-supply mode, VSS connects to the negative rail (e.g., –2.5V) and VDD to the positive rail (e.g., +2.5V), preserving rail-to-rail input/output swing relative to the new common-mode midpoint. The MAX4491AKA+T maintains its 10MHz GBW and 10V/µs slew rate across this range.

What is the input common-mode voltage range specification for the MAX4491AKA+T?

The MAX4491AKA+T features a true rail-to-rail input common-mode voltage range extending from VSS to VDD, confirmed in the Electrical Characteristics table (VCM = VSS to VDD) and Detailed Description section. This is achieved via parallel N- and P-channel input stages that seamlessly transition near VSS + 1.2V and VDD – 1.2V. At 125°C, the range remains fully functional - critical for MAX4491AKA+T use in automotive ambient temperature monitoring.

Is the MAX4491AKA+T pin-compatible with other op amps in the MAX449x family?

No - the MAX4491AKA+T uses the SOT23-5 package with 5-pin configuration (IN+, VSS, IN−, OUT, VDD), while the MAX4490 uses SC70-5 (same pinout but smaller footprint) and the MAX4492 uses 14-pin TSSOP/SO. Though functionally similar, mechanical compatibility is limited to MAX4490 variants in SC70-5; MAX4491AKA+T requires SOT23-5 land pattern and cannot substitute for MAX4490AXK-T without PCB revision.

What is the typical input offset voltage drift over temperature for the MAX4491AKA+T?

The MAX4491AKA+T exhibits a typical input offset voltage drift of ±0.5µV/°C over –40°C to +125°C, inferred from the Input Offset Voltage vs. Temperature plot (MAX4490 toc03) and confirmed by the datasheet's note that VOS is tested at both ends of the common-mode range. This low drift ensures <100µV total offset error across full automotive temperature range - essential for MAX4491AKA+T deployment in precision current-sense amplifiers.