Analog Devices Inc./Maxim Integrated MAX921ESA+

Overview

The MAX921ESA+ from Maxim Integrated is a single, ultra-low-power, rail-to-rail input comparator with integrated 1.182V ±1% bandgap reference, programmable hysteresis via HYST pin, and TTL/CMOS-compatible output capable of sourcing up to 40mA. It operates from +2.5V to +11V single supply (or ±1.25V to ±5.5V dual supply), features 4μA max quiescent current over –40°C to +85°C, and supports battery-powered threshold detection with minimal power overhead.

For engineers reviewing the MAX921ESA+ datasheet, MAX921ESA+ pinout, MAX921ESA+ application, or MAX921ESA+ equivalent, this page delivers verified electrical specs, package-confirmed pin functions, real-world use cases in low-power sensing, and validated alternative options - all grounded in Maxim's official 19-0115 Rev 7 documentation.

Technical Context

The MAX921ESA+ integrates a precision micropower comparator and a stable 1.182V reference referenced to V−, not GND. Its unique output stage eliminates crowbar current during transitions, minimizing supply-line parasitic feedback and enabling stable operation without strict layout constraints.

Input common-mode range extends from V− to (V+ − 1.3V); output swings from V+ to GND in single-supply mode. Hysteresis is implemented externally via two resistors on the HYST pin (REF–HYST voltage sets hysteresis band width), avoiding feedback networks and simplifying design for noise-immune threshold detection.

Key Specifications

Pinout & Package

MAX921ESA+ uses an 8-pin SO (Small Outline) package, RoHS-compliant, with standard JEDEC MS-012AC footprint (5.0mm × 4.0mm, 1.27mm pitch).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar comparator applications.

Compared with LM393MX/NOPB and TLV3701IDBVR, the MAX921ESA+ uniquely combines integrated ±1% reference, programmable hysteresis via HYST pin, 40mA output drive, and sub-4μA quiescent current - making it optimal for self-contained, battery-sensitive threshold detection where BOM reduction and layout simplicity are essential.

Availability

MAX921ESA+ is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, window comparators, and oscillator circuits requiring stable component supply across industrial temperature ranges.

Supply support for MAX921ESA+ 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) designs precision analog and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX921ESA+ belongs to the MAX921–MAX924 micropower comparator family, engineered specifically for ultra-low-power, single-supply threshold detection with integrated reference and hysteresis - targeting portable instrumentation, energy-harvesting systems, and long-life battery applications.

FAQ

What is the operating temperature range of the MAX921ESA+?

The MAX921ESA+ is rated for –40°C to +85°C (industrial temperature range). This is confirmed in the Ordering Information table, where "ESA" suffix denotes the extended temperature grade. All electrical specifications - including 4μA max supply current and 1.182V ±1% reference - are guaranteed across this full range, making MAX921ESA+ suitable for outdoor, automotive under-hood, and industrial control environments.

Does the MAX921ESA+ require external hysteresis components?

The MAX921ESA+ supports both internal and external hysteresis implementation. Its dedicated HYST pin allows simple two-resistor hysteresis programming (REF → HYST → V−), delivering up to 100mV hysteresis band without feedback loops. If no hysteresis is needed, connect HYST directly to REF. Unlike comparators lacking this pin, MAX921ESA+ does not require external positive-feedback networks for basic hysteresis - reducing component count and layout complexity.

Can the MAX921ESA+ operate from a 3V supply?

Yes, the MAX921ESA+ operates from +2.5V to +11V single supply, fully supporting 3V systems. At V+ = 3V, it maintains 4μA max supply current, 1.182V reference accuracy (±1%), and functional hysteresis control. Input common-mode range extends to (3V − 1.3V) = 1.7V, and output swings from 3V to GND - ensuring compatibility with 3V logic families and low-voltage sensors without level shifting.

What is the purpose of the REF pin on the MAX921ESA+?

The REF pin on the MAX921ESA+ outputs a precision 1.182V ±1% bandgap reference voltage referenced to V− (not GND). It sources up to 25μA and sinks up to 15μA, enabling direct use as a stable threshold reference for the comparator inputs or external circuitry. The REF pin must not be bypassed, as capacitive loading degrades noise performance and stability - a key design requirement explicitly stated in the datasheet.

How does the MAX921ESA+ eliminate supply-line glitches during output transitions?

The MAX921ESA+ eliminates supply-line glitches by using a unique output stage that prevents crowbar current - simultaneous conduction of pull-up and pull-down devices during logic transitions. This architecture removes transient current spikes into V+ and GND, minimizing parasitic feedback through shared supply paths. As a result, MAX921ESA+ achieves stable operation even with suboptimal PCB layout or high-impedance supplies, unlike conventional comparators requiring careful decoupling and routing.