Analog Devices Inc./Maxim Integrated MAX951EUA

Overview

MAX951EUA from Maxim Integrated is an ultra-low-power, single-supply analog IC integrating a unity-gain-stable op amp, a comparator with internal 1.2V ±2% bandgap reference, and rail-to-rail output stages in an 8-pin μMAX package. It operates from 2.7V to 7V, draws 7μA typical supply current, and supports common-mode input down to VSS and outputs swinging from VSS to VDD - ideal for battery-powered smoke detectors requiring continuous sensor buffering and threshold-triggered alarm generation.

For engineers reviewing the MAX951EUA datasheet, MAX951EUA pinout, MAX951EUA application, or MAX951EUA equivalent, key selection considerations include its integrated reference accuracy (±2% over –40°C to +85°C), rail-to-rail I/O capability, 1.6V input headroom from VDD, 20kHz gain-bandwidth product, and verified performance in photodiode preamp and low-frequency alarm detector circuits.

Technical Context

The MAX951EUA implements a monolithic CMOS architecture combining three functional blocks: a unity-gain-compensated op amp with 20kHz GBW and 12.5V/ms slew rate; a comparator with ±3mV internal hysteresis, 22µs propagation delay at 10mV overdrive, and 40mA continuous output sourcing; and a buffered 1.2V bandgap reference with ±2% initial accuracy and <1.5% load regulation over ±20µA.

All blocks share a common 2.7V–7V single supply, operate across –40°C to +85°C, and feature rail-to-rail input (VSS to VDD–1.6V) and output (VSS to VDD) ranges. The reference is internally connected to COMPIN–, eliminating external components for threshold-based detection while maintaining isolation from op amp inputs via dedicated pins.

Key Specifications

Pinout & Package

MAX951EUA is housed in an 8-pin μMAX package (2.1mm × 2.1mm, 0.5mm pitch), specified for –40°C to +85°C operation. The μMAX footprint is pin-compatible with SO and DIP variants but offers 60% area reduction for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar op amp + comparator + reference applications.

Compared with MAX952EUA, the MAX951EUA trades bandwidth for guaranteed unity-gain stability in high-impedance sensor interfaces; compared with TLV2304IDR, it delivers functional integration that reduces design cycle time and improves long-term threshold accuracy in battery-operated safety-critical systems.

Availability

MAX951EUA is available at Aetrix Electronics and suitable for smoke detectors, infrared receivers, low-frequency alarm detectors, and bar-code readers requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for MAX951EUA 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 company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.

The MAX951–MAX954 family was designed to deliver integrated analog functionality - op amp, comparator, and reference - in ultra-low-power, single-supply configurations for portable and safety-critical instrumentation where battery life and reliability are paramount.

FAQ

What is the operating temperature range for the MAX951EUA?

The MAX951EUA is rated for operation from –40°C to +85°C, matching the extended industrial temperature grade. This range is validated across all electrical parameters including reference accuracy (±2%), input offset voltage (≤5mV), and supply current (7μA typ), making it suitable for smoke detectors deployed in uncontrolled environments such as garages or attics where ambient temperatures fluctuate widely.

Does the MAX951EUA require external bypass capacitors on the REF pin?

No - the MAX951EUA reference output must not be bypassed. The internal 1.2V bandgap reference is stable only with capacitive loads under 100pF. Adding a capacitor to the REF pin (pin 6) introduces phase shift that can cause oscillation or reference voltage droop. For noise-sensitive applications, a low-pass RC filter (e.g., 10kΩ + 100pF) may be placed between REF and downstream circuitry, but never directly on the REF pin itself.

Can the MAX951EUA drive a 1000pF capacitive load with the op amp?

Yes - the MAX951EUA op amp is specifically characterized to drive loads up to 1000pF while maintaining stability and linearity. This capability is confirmed in the "OP AMP PERCENT OVERSHOOT vs. CAPACITIVE LOAD" graph (Figure TOC12), which shows ≤15% overshoot at 1000pF with unity-gain configuration. This makes it suitable for driving ADC input capacitors or long PCB traces in sensor interface applications without external isolation resistors.

How does the internal hysteresis of the MAX951EUA comparator improve reliability in smoke detection?

The MAX951EUA comparator includes ±3mV internal hysteresis, which creates a 6mV decision window around the 1.2V reference. This prevents output oscillation when the ion chamber voltage rises slowly during smoke accumulation - a common failure mode in low-power detectors. Unlike external hysteresis networks, this feature requires no additional resistors or board area and remains stable across temperature and supply voltage variations, directly enhancing false-alarm immunity in UL-certified smoke alarms.

Is the MAX951EUA pin-compatible with other packages in the MAX951–MAX954 family?

Yes - the MAX951EUA (8-pin μMAX) shares identical pinout and electrical specifications with the MAX951EPA (8-pin PDIP) and MAX951ESA (8-pin SO). All three packages use the same pin numbering and function mapping (e.g., pin 6 = REF/COMPIN−, pin 7 = COMPOUT). This allows drop-in replacement during prototyping or volume production scaling without PCB redesign, provided thermal and mechanical constraints of the μMAX package (2.1mm × 2.1mm) are accommodated.