Analog Devices Inc./Maxim Integrated MAX921CUA

Overview

The MAX921CUA 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 portable instrumentation and low-power sensor interfaces.

For engineers reviewing the MAX921CUA datasheet, MAX921CUA pinout, MAX921CUA application, or MAX921CUA equivalent, key selection criteria include its 4μA max quiescent current over 0°C to +70°C, rail-to-rail input range (V− to V+ −1.3V), 12μs propagation delay at 10mV overdrive, internal reference accuracy, and μMAX-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX921CUA implements a micropower comparator core paired with a precision 1.182V bandgap 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 stringent layout constraints.

Hysteresis is implemented externally via the HYST pin using two resistors-no feedback loop required-enabling adjustable hysteresis bands up to 100mV while maintaining sub-4μA supply current. Input common-mode range extends from V− to V+ −1.3V, supporting direct sensing near supply rails in single-supply systems.

Key Specifications

Pinout & Package

Package: 8-pin μMAX (3mm × 3mm, 0.5mm pitch), thermally enhanced leadless package optimized for compact, high-density designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMV331M5X and TLV3691DBVR, the MAX921CUA delivers integrated reference, programmable hysteresis, and 40mA push-pull output in a single μMAX-8 package-reducing BOM count and PCB area while enabling faster design iteration for precision threshold detection.

Availability

MAX921CUA is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, window comparators, and oscillator circuits requiring stable component supply and long-term lifecycle support.

Supply support for MAX921CUA 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 MAX921CUA belongs to the MAX921–MAX924 micropower comparator family, designed specifically for ultra-low-power, precision threshold detection in space- and energy-constrained applications such as portable medical devices and remote sensors.

FAQ

What is the maximum supply voltage for the MAX921CUA?

The MAX921CUA supports a single-supply voltage range of +2.5V to +11V. When operated from dual supplies, it accepts ±1.25V to ±5.5V. The absolute maximum rating is +12V between V+ and V−, but operation above +11V is not guaranteed. For reliable performance across temperature, the recommended maximum is +11V, as specified in the Electrical Characteristics table under "Supply Voltage Range."

Does the MAX921CUA require external hysteresis components?

The MAX921CUA does not require external hysteresis components to function-it operates as a standard comparator with zero hysteresis when HYST is tied to REF. However, to add programmable hysteresis (up to 100mV), two external resistors (R1 between REF and HYST, R2 between HYST and V−) are used. This method avoids feedback loops and preserves low quiescent current, unlike traditional positive-feedback configurations.

Can the MAX921CUA operate from a 3V supply?

Yes, the MAX921CUA is fully specified and characterized for operation from a +3V single supply. At V+ = 3V, it maintains ≤4μA supply current, 1.182V ±1% reference accuracy, and 14μs propagation delay (10mV overdrive). Input common-mode range extends from V− (GND) to V+ −1.3V = 1.7V, supporting wide dynamic range sensing in 3V systems.

What is the purpose of the REF pin on the MAX921CUA?

The REF pin on the MAX921CUA provides a precision 1.182V ±1% bandgap reference voltage referenced to V− (not GND). It serves as a stable, low-drift threshold source for IN+ or IN−, eliminating the need for external references or trimmed resistor dividers. The REF output can source up to 25μA and sink up to 15μA at +25°C, and must not be bypassed to preserve noise performance.

Is the MAX921CUA pin-compatible with other MAX92x variants?

The MAX921CUA is pin-compatible with the MAX921CPA (DIP-8) and MAX921CSA (SO-8) within the same temperature grade (0°C to +70°C), sharing identical pinout and electrical behavior. It is not pin-compatible with MAX922CUA, MAX923CUA, or MAX924 variants due to differing channel counts, internal reference presence, and pin assignments (e.g., MAX922 lacks REF and HYST pins).