Analog Devices Inc./Maxim Integrated MAX921CUA+T

Overview

The MAX921CUA+T 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 0°C to +70°C, and supports battery-powered threshold detection with input common-mode range extending from V− to V+ − 1.3V.

For engineers reviewing the MAX921CUA+T datasheet, MAX921CUA+T pinout, MAX921CUA+T application, or MAX921CUA+T equivalent, key selection criteria include its micropower operation, internal reference accuracy, hysteresis configurability without external feedback, and robust output drive for direct LED or logic interfacing in space-constrained portable systems.

Technical Context

The MAX921CUA+T 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, minimizing supply-line parasitic feedback and enabling stable operation without stringent PCB layout requirements.

It supports true single-supply operation with V− tied to GND, and its input voltage range includes the negative rail-critical for ground-referenced sensing. The HYST pin enables precise, resistor-programmable hysteresis (up to 100mV band) independent of external feedback networks, simplifying noise-immune threshold design.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM393DR and TLV3701IDBVR, the MAX921CUA+T delivers superior integration (reference + hysteresis control + 40mA drive), tighter reference accuracy, and guaranteed micropower performance across its full operating temperature range-making it optimal for compact, battery-critical designs where BOM reduction and long-term stability are essential.

Availability

MAX921CUA+T is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, window comparators, and oscillator circuits requiring stable component supply with guaranteed commercial-temperature performance and μMAX footprint compatibility.

Supply support for MAX921CUA+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 semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX921CUA+T belongs to the MAX921–MAX924 micropower comparator family, designed specifically for ultra-low-power sensing and threshold detection in portable and energy-harvesting systems where supply current, reference accuracy, and ease of hysteresis implementation are critical.

FAQ

What is the maximum supply voltage for the MAX921CUA+T in single-supply operation?

The MAX921CUA+T supports a single-supply voltage range of +2.5V to +11V. When operated with V− tied to GND, the absolute maximum voltage applied between V+ and GND is +12V per Absolute Maximum Ratings, but functional operation is specified up to +11V. Exceeding +11V may degrade reference accuracy or long-term reliability.

Can the MAX921CUA+T operate from a dual supply, and what is the range?

Yes, the MAX921CUA+T supports dual-supply operation from ±1.25V to ±5.5V. In this configuration, V+ connects to the positive rail and V− to the negative rail; GND is not used. The output swings from V+ to V−, maintaining TTL compatibility when V+ = +5V and V− = 0V, or bipolar compatibility when V+ = +5V and V− = −5V.

How is hysteresis programmed on the MAX921CUA+T, and what is the maximum achievable band?

Hysteresis is programmed using the HYST pin with two resistors: R1 from REF to HYST, and R2 from HYST to V−. The HYST voltage is adjustable from REF down to REF − 50mV, yielding a maximum hysteresis band (VHB) of approximately 100mV. This method avoids external feedback and ensures fast, stable hysteresis action without additional components.

What is the output drive capability of the MAX921CUA+T, and how does it affect load interfacing?

The MAX921CUA+T output continuously sources ≥40mA and sinks ≥5mA. This allows direct driving of LEDs, small solenoids, or logic inputs without external buffers. At V+ = 5V, it can source 100mA in short pulses if thermal limits permit. The push-pull structure eliminates need for pull-up resistors, simplifying interface to TTL/CMOS loads.

Is the internal reference of the MAX921CUA+T referenced to GND or to V−?

The internal 1.182V reference of the MAX921CUA+T is referenced to V−, not GND. When used in single-supply mode (V− = GND), REF = 1.182V relative to GND. In dual-supply mode (e.g., V+ = +5V, V− = −5V), REF = 1.182V above V−, i.e., −3.818V relative to GND. This architecture ensures consistent reference behavior across both supply configurations.