Analog Devices Inc./Maxim Integrated MAX981ESA+T

Overview

The MAX981ESA+T from Maxim Integrated is a single, ultra-low-power, open-drain comparator with internal 1.182V ±2% voltage reference and programmable hysteresis via HYST pin. It operates from 2.5V to 11V single supply (or ±1.25V to ±5.5V dual), draws ≤4µA supply current over temperature, supports rail-to-rail input down to V− and within 1.3V of V+, and features separate GND for output stage-enabling bipolar-to-single-ended level translation in battery-powered threshold detection.

For engineers reviewing the MAX981ESA+T datasheet, MAX981ESA+T pinout, MAX981ESA+T application, or MAX981ESA+T equivalent, key selection considerations include its 4µA quiescent current, ±2% reference accuracy, 12µs propagation delay at 10mV overdrive, open-drain output with 11V output range, and HYST-pin-based hysteresis programming without external feedback.

Technical Context

The MAX981ESA+T integrates a micropower bandgap reference referenced to V− (not GND) and a single comparator with input common-mode range from V− to (V+ − 1.3V). Its HYST pin accepts voltages from (REF − 50mV) to REF, enabling precise hysteresis band control up to 100mV via two external resistors.

Output stage uses an N-channel MOSFET sinking to GND (separate GND pin), allowing level-shifting across supply domains. Propagation delay is 12µs (high-to-low) at 10mV overdrive with 100pF load and 1MΩ pullup; low-to-high response depends on RC time constant and is not internally accelerated.

Key Specifications

Pinout & Package

MAX981ESA+T is housed in an 8-pin SO (Small Outline) package with gull-wing leads, JEDEC MS-012AC compliant, body size 4.9mm × 3.9mm × 1.75mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX971ESA+, the MAX981ESA+ trades ±1% reference accuracy for lower cost while retaining identical hysteresis implementation and level-shifting capability; compared with TLV3691IDBVR, it provides integrated reference and open-drain output with separate GND-making it uniquely suited for bipolar-to-single-ended translation without added components.

Availability

MAX981ESA+T is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, level translators, and oscillator circuits requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX981ESA+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) designs precision analog and mixed-signal ICs for power, sensing, interface, and timing applications in industrial, medical, and communications systems.

The MAX981ESA+T belongs to the MAX97x/MAX98x micropower comparator family, engineered specifically for ultra-low-quiescent-current sensing and threshold detection in space- and energy-constrained applications.

FAQ

What is the reference voltage accuracy of the MAX981ESA+T over temperature?

The MAX981ESA+T features an internal 1.182V bandgap reference with ±2% accuracy over the 0°C to +70°C commercial temperature range. At extended temperatures (−40°C to +85°C), accuracy degrades to ±3%, as specified in the Electrical Characteristics table under "Reference Voltage" for MAX981–MAX984. This tolerance directly impacts absolute threshold accuracy in reference-based comparator configurations.

Can the MAX981ESA+T operate from a 1.8V single supply?

No-the MAX981ESA+T has a guaranteed minimum single-supply operating voltage of 2.5V. While some comparators in the MAX97x/MAX98x family (e.g., MAX974) may function below 2.5V, the MAX981ESA+T is not characterized or specified for operation below this voltage. Attempting 1.8V operation risks undefined behavior, increased propagation delay, and loss of reference regulation.

How is hysteresis programmed on the MAX981ESA+T?

Hysteresis is programmed using the HYST pin: connect R1 between REF and HYST, and R2 between HYST and V−. The hysteresis band (V_HB) ≈ 2 × (V_REF − V_HYST), with V_HYST adjustable from (REF − 50mV) to REF. For example, setting V_HYST = REF − 25mV yields ~50mV hysteresis. Do not leave HYST floating; tie to REF if unused.

Does the MAX981ESA+T require a bypass capacitor on the REF pin?

No-bypassing the REF pin is explicitly prohibited per the datasheet. The internal reference is designed for direct connection to external resistive dividers or HYST networks. Adding capacitance to REF can cause instability, increased noise, or reference regulation failure. Power supply pins (V+ and V−) may use 100nF bypass capacitors only if supply impedance is high or leads are long.

What is the maximum output sink current of the MAX981ESA+T?

The MAX981ESA+T output transistor is rated for continuous 50mA sink current, as stated in Absolute Maximum Ratings. Under typical operating conditions (e.g., 5V supply, 1.8mA load), output low voltage is ≤0.4V. Sink capability decreases at lower supply voltages-e.g., at 3V supply, VOL rises to ~0.6V at 0.8mA-so design margins must account for V+ dependency.