Analog Devices Inc./Maxim Integrated MAX971CSA+

Overview

The MAX971CSA+ from Maxim Integrated is a single, ultra-low-power, open-drain comparator with integrated 1.182V ±1% precision 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 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 MAX971CSA+ datasheet, MAX971CSA+ pinout, MAX971CSA+ application, or MAX971CSA+ equivalent, key selection criteria include its 4µA quiescent current, 1.182V ±1% internal reference accuracy, 12µs propagation delay at 10mV overdrive, open-drain output with 11V output voltage range, and HYST-pin-based hysteresis programming without external feedback.

Technical Context

The MAX971CSA+ integrates a bandgap voltage reference referenced to V− (not GND), delivering 1.182V ±1% over 0°C to +70°C. Its comparator core uses micropower design with input common-mode range extending from V− to (V+ − 1.3V), and supports operation with inputs up to 300mV beyond supply rails without damage.

Its open-drain output sinks current to GND (not V−), enabling direct use in wire-OR configurations and level-shifting applications-e.g., translating ±5V signals to 3.3V logic. Hysteresis is implemented by applying a voltage between REF and HYST pins, with programmable band up to 100mV, eliminating need for external positive-feedback networks.

Key Specifications

Pinout & Package

MAX971CSA+ is housed in an 8-pin SO (Small Outline) package with gull-wing leads, JEDEC MS-012AC compliant, 150-mil body width, and standard SOIC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV3701IDBVR and LMV7235M5X, the MAX971CSA+ uniquely integrates ±1% reference and HYST-pin hysteresis in a single 8-pin SO package-reducing total solution size and eliminating calibration drift from external dividers, making it optimal for compact, self-contained threshold detectors.

Availability

MAX971CSA+ is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, and level translators requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for MAX971CSA+ 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 MAX971CSA+ belongs to Maxim's micropower comparator family, engineered specifically for ultra-low-power, reference-integrated threshold detection in space-constrained, battery-operated equipment.

FAQ

What is the maximum supply voltage for the MAX971CSA+?

The MAX971CSA+ supports a maximum total supply voltage of 11V in single-supply mode (V+ to V−), or ±5.5V in dual-supply configuration. Absolute maximum ratings specify V+ to V− up to +12V, but functional operation is guaranteed only up to 11V. Exceeding 11V may cause parametric degradation or reliability risk. The MAX971CSA+'s output stage remains functional even with V+ = 0V, provided V− is at GND and load is pulled up externally.

Does the MAX971CSA+ require an external reference for basic comparator operation?

No, the MAX971CSA+ does not require an external reference for basic comparator operation. It includes an internal 1.182V ±1% bandgap reference referenced to V−, accessible at the REF pin. This reference can directly drive the HYST pin for hysteresis or serve as a stable threshold source. External references are optional-for example, to override the internal reference or achieve tighter tolerance-and are not needed for standard threshold detection using the built-in reference.

How is hysteresis programmed on the MAX971CSA+?

Hysteresis on the MAX971CSA+ is programmed using the HYST pin: connect a resistor divider between REF and V−, with the HYST pin tied to the midpoint. The voltage difference between REF and HYST sets the hysteresis band-up to 50mV yields up to 100mV total hysteresis. For example, with R1 = 2.4MΩ from REF to HYST and R2 = 2.4MΩ from HYST to V−, HYST = 0.5 × REF ≈ 0.591V, giving ~591mV hysteresis band. The MAX971CSA+ datasheet provides exact equations for precise calculation based on desired VHB.

Can the MAX971CSA+ operate from a 2.5V supply?

Yes, the MAX971CSA+ is fully specified to operate from a minimum single-supply voltage of 2.5V (V+ = 2.5V, V− = GND). At 2.5V, supply current remains ≤4µA, input common-mode range extends from 0V to 1.2V, and propagation delay increases to ~18µs (vs. 12µs at 5V). The internal reference remains functional down to ~2.2V, though accuracy degrades below 2.5V. Operation below 2.5V is not guaranteed and requires prototype validation across temperature and load conditions.

What is the purpose of the separate GND pin on the MAX971CSA+?

The separate GND pin on the MAX971CSA+ serves as the return path for the open-drain output transistor-distinct from the V− supply pin. This allows the output to sink current to system ground while V− is tied to GND in single-supply mode, or to a negative rail in dual-supply mode. It enables true level translation: for example, the output can drive a 3.3V logic input while the comparator core runs from ±5V supplies. Without this dedicated GND, output swing would be limited to V−, preventing interoperability across voltage domains.