Analog Devices Inc./Maxim Integrated MAX981CUA+T

Overview

The MAX981CUA+T from Maxim Integrated is a single-channel, ultra-low-power comparator with integrated 1.182V ±2% bandgap reference, programmable hysteresis via HYST pin, open-drain output, and operation from 2.5V to 11V single supply (or ±1.25V to ±5.5V dual supply). It draws ≤4µA supply current over temperature and supports input common-mode range from V− to V+ − 1.3V - ideal for battery-powered threshold detection in portable instrumentation.

For engineers reviewing the MAX981CUA+T datasheet, MAX981CUA+T pinout, MAX981CUA+T application, or MAX981CUA+T equivalent, key selection criteria include its micropower consumption, internal reference tolerance, hysteresis configurability without external feedback, and separate GND pin enabling bipolar-to-single-ended level translation.

Technical Context

The MAX981CUA+T implements a rail-to-rail input comparator stage with an internal 1.182V reference referenced to V−, not GND. Its HYST pin allows precise hysteresis programming using two external resistors - eliminating need for positive-feedback networks and reducing design complexity versus discrete solutions.

It features an open-drain output with dedicated GND terminal (Pin 1), permitting operation with total supply voltages up to 11V and enabling robust level-shifting between bipolar and single-ended domains. Propagation delay is 12µs (10mV overdrive) with 100pF load and 1MΩ pull-up.

Key Specifications

Pinout & Package

MAX981CUA+T is housed in an 8-pin µMAX package (3mm × 3mm, 0.8mm height), pin-compatible with SO and DIP variants. The package features exposed pad for thermal enhancement and is RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX971CUA+T, the MAX981CUA+T trades ±1% reference accuracy for lower cost while retaining identical micropower operation, hysteresis method, and level-shifting capability; versus TLV3701IDBVR, it integrates reference and hysteresis control but consumes slightly higher quiescent current.

Availability

MAX981CUA+T is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, and level translators requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for MAX981CUA+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, automotive, and communications markets.

The MAX981CUA+T belongs to the MAX97x/MAX98x micropower comparator family, designed specifically for ultra-low-power sensing, battery monitoring, and precision threshold detection in space- and energy-constrained applications.

FAQ

What is the maximum supply voltage for MAX981CUA+T in single-supply operation?

The MAX981CUA+T supports a single-supply voltage range of 2.5V to 11V. When operated with V− tied to GND, the maximum allowable V+ is 11V. Absolute maximum rating for V+ to V− is 12V, but functional operation is specified up to 11V. Exceeding 11V may compromise reference stability and output stage reliability. The MAX981CUA+T datasheet confirms this limit under "Absolute Maximum Ratings" and "Electrical Characteristics."

Does MAX981CUA+T require an external reference, or is the internal reference usable directly?

The MAX981CUA+T includes a fully functional 1.182V ±2% internal bandgap reference accessible at the REF pin. It is designed for direct use - no external components are needed, and bypassing is explicitly discouraged. The reference sources up to 25µA and sinks up to 15µA, sufficient to drive HYST networks and small external loads. This eliminates the need for external references in most threshold-detection applications using the MAX981CUA+T.

How is hysteresis programmed on MAX981CUA+T, and what is the maximum achievable hysteresis band?

Hysteresis on the MAX981CUA+T is programmed by connecting two resistors between REF, HYST, and V−. The HYST pin accepts voltages from REF − 50mV to REF, producing a hysteresis band (V_HB) ≈ 2 × (REF − V_HYST). With the maximum 50mV differential, the MAX981CUA+T achieves up to 100mV hysteresis band. Equations for R1 and R2 are provided in the datasheet, with recommended I_REF between 0.1µA and 4µA to ensure accuracy and low power.

Can MAX981CUA+T operate from a 3V supply, and how does performance change vs. 5V?

Yes, the MAX981CUA+T operates reliably from 3V single supply. At 3V, supply current remains ≤4µA, input common-mode range shifts to V− to V+ − 1.3V (i.e., 0V to 1.7V), and propagation delay increases slightly (e.g., 14µs typical at 10mV overdrive). Reference output stays stable at 1.182V ±2%, and output sink capability decreases modestly - VOL = 0.4V at 0.8mA. All specifications are validated in the "3V Operation" section of the MAX981CUA+T datasheet.

What is the purpose of the separate GND pin (Pin 1) on MAX981CUA+T?

The separate GND pin (Pin 1) on the MAX981CUA+T is the dedicated ground connection for the open-drain output transistor. This isolation allows the output to sink current to a ground node independent of the signal ground (V−), enabling level translation between different voltage domains - for example, converting a ±5V input signal into a 0–3.3V logic-level output. It also permits operation with dual supplies (±1.25V to ±5.5V) while maintaining 11V output swing capability. This feature is intrinsic to the MAX981CUA+T's architecture.