Analog Devices Inc./Maxim Integrated MAX921ESA

Overview

The MAX921ESA from Maxim Integrated is a single-channel, ultra-low-power comparator with integrated 1.182V ±1% bandgap reference, programmable hysteresis via HYST pin, TTL/CMOS-compatible output capable of sourcing up to 40mA, and operation from +2.5V to +11V single supply (or ±1.25V to ±5.5V dual supply). It targets battery-powered threshold detection in industrial sensors and portable instrumentation.

For engineers reviewing the MAX921ESA datasheet, MAX921ESA pinout, MAX921ESA application, or MAX921ESA equivalent, key selection criteria include its 4μA max quiescent current over –40°C to +85°C, rail-to-rail input range (V– to V+ – 1.3V), 12μs propagation delay at 10mV overdrive, internal reference accuracy, and SO-8 package compatibility with legacy layouts.

Technical Context

The MAX921ESA implements a micropower comparator core paired with a precision bandgap reference referenced to V–, not GND. Its unique output stage eliminates crowbar current during transitions, reducing supply-line parasitic feedback and improving stability without mandatory bypassing.

It supports hysteresis configuration via external resistors on the HYST pin (REF–HYST voltage sets hysteresis band width up to 100mV), and features input common-mode range extending to the negative rail - enabling direct sensing of signals near ground in single-supply systems.

Key Specifications

Pinout & Package

MAX921ESA is housed in an 8-pin SO (Small Outline) package, pin-compatible with industry-standard SOIC-8 footprints and suitable for automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM393DR and TLV3701CDR, the MAX921ESA uniquely combines sub-5μA operation, ±1% factory-trimmed reference, and dedicated HYST pin for simple, precise hysteresis - making it optimal for long-life, self-contained threshold detection where layout simplicity and supply noise immunity are critical.

Availability

MAX921ESA is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, 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 systems.

The MAX921ESA belongs to the MAX921–MAX924 micropower comparator family, engineered specifically for ultra-low-power threshold detection in space- and energy-constrained systems where internal reference accuracy and hysteresis simplicity are essential.

FAQ

What is the maximum operating temperature range for the MAX921ESA?

The MAX921ESA is rated for operation from –40°C to +85°C, as confirmed by its ordering code suffix "ESA" and the Electrical Characteristics tables specifying performance across this extended temperature range. This makes it suitable for industrial and automotive cabin applications where ambient temperatures exceed commercial-grade limits. The MAX921ESA maintains ≤4μA supply current and ±1% reference accuracy across this full range.

Does the MAX921ESA require external hysteresis components?

The MAX921ESA does not require external hysteresis components to implement basic hysteresis - it provides a dedicated HYST pin that, when biased with two resistors between REF and V–, configures adjustable hysteresis (0–100mV band) without feedback networks or op-amps. If no hysteresis is needed, connect HYST directly to REF. This internal architecture reduces component count and layout sensitivity compared to conventional comparator hysteresis methods.

Can the MAX921ESA operate from a 3V supply?

Yes, the MAX921ESA operates from a +2.5V to +11V single supply, fully supporting 3V nominal systems. At V+ = 3V, it delivers 12μs propagation delay (10mV overdrive), 4μA max supply current, and maintains input common-mode range from V– to V+ – 1.3V (i.e., 0V to 1.7V). The internal 1.182V reference remains functional and accurate, enabling reliable threshold detection in 3V microcontroller-based designs.

What is the purpose of the V– pin on the MAX921ESA?

The V– pin on the MAX921ESA serves as the negative supply terminal and defines the reference point for the internal 1.182V reference (which is specified relative to V–, not GND). In single-supply operation, V– is connected to GND; in dual-supply mode, it accepts voltages down to –5.5V. This pin also establishes the lower bound of the input common-mode range and the output low-voltage limit (V– + 0.4V), ensuring correct functionality across both supply configurations.

Is the MAX921ESA pin-compatible with other comparators in the MAX92x family?

The MAX921ESA is pin-compatible with the MAX921CPA, MAX921CSA, and MAX921CUA variants - all share identical 8-pin SO (or DIP/μMAX) pinouts per the Pin Configurations diagram. However, it is not pin-compatible with MAX922ESA, MAX923ESA, or MAX924ESE due to differing channel counts, reference presence, and pin assignments (e.g., MAX922 lacks REF and HYST pins; MAX924 uses 16 pins). Always verify pin function mapping using the MAX921-specific Pin Descriptions table.