Analog Devices Inc./Maxim Integrated MAX971CPA

Overview

The MAX971CPA from Maxim Integrated is a single, ultra-low-power, open-drain comparator with integrated 1.182V ±1% voltage reference and programmable hysteresis via HYST pin. It operates from 2.5V to 11V single supply (or ±1.25V to ±5.5V dual supply), features 4µA max supply current over temperature, rail-to-rail input range down to V−, and supports level translation in battery-powered threshold detection systems.

For engineers reviewing the MAX971CPA datasheet, MAX971CPA pinout, MAX971CPA application, or MAX971CPA equivalent, key selection criteria include its 1.182V ±1% internal reference accuracy, 12µs propagation delay at 10mV overdrive, separate GND pin for output stage enabling bipolar-to-single-ended conversion, and compatibility with 8-pin PDIP packaging for through-hole prototyping and industrial control interfaces.

Technical Context

The MAX971CPA integrates a precision bandgap reference referenced to V− (not GND) and a single comparator with open-drain N-channel MOSFET output sinking to GND - distinct from MAX972/MAX973 variants that sink to V−. Its HYST pin enables hysteresis programming using two external resistors without feedback loops or complex calculations.

This device supports true single-supply operation (V− = GND) while maintaining full input common-mode range from V− to (V+ − 1.3V), and delivers 11V output swing capability independent of supply presence - critical for level-shifting between ±5V and 3.3V domains in portable instrumentation and power-good monitoring circuits.

Key Specifications

Pinout & Package

MAX971CPA uses an 8-pin plastic DIP package with through-hole mounting. Pin functions are validated per Maxim's official pin configuration diagram (Rev 3, Feb 2003).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX971CPA, MAX981CPA trades reference accuracy for lower cost in less demanding applications, while MAX921CPA replaces open-drain flexibility with push-pull simplicity - neither offers pin-compatible replacement without circuit redesign.

Availability

MAX971CPA 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-lifecycle designs.

Supply support for MAX971CPA 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 markets.

The MAX97x/MAX98x comparator family targets ultra-low-power, single/dual-supply sensing systems - emphasizing micropower operation, integrated references, and flexible hysteresis for reliable threshold detection in resource-constrained environments.

FAQ

What is the reference voltage accuracy of the MAX971CPA over its operating temperature range?

The MAX971CPA features a 1.182V internal bandgap reference with ±1% accuracy over the 0°C to +70°C commercial temperature range. This specification is guaranteed per Maxim's datasheet ordering information table and applies specifically to the MAX971CPA variant - not the ±2% MAX98x series. The reference is referenced to V−, not GND, and maintains stability under load currents up to 25µA source / 15µA sink.

Can the MAX971CPA operate from a 3V single supply, and what performance changes occur?

Yes, the MAX971CPA operates from 3V single supply (within its 2.5V–11V range). At 3V, typical supply current is 2.4µA (vs. 3.2µA at 5V), propagation delay increases to ~15µs (from 12µs at 5V), and output sink capability drops slightly - but all specifications remain guaranteed. Input common-mode range stays V− to (V+ − 1.3V), so usable input span is 0V to 1.7V at 3V supply.

How is hysteresis implemented on the MAX971CPA, and what is the maximum achievable hysteresis band?

Hysteresis on the MAX971CPA is implemented using the HYST pin with two external resistors: R1 from REF to HYST, and R2 from HYST to V−. The HYST pin voltage range is (REF − 50mV) to REF, yielding a maximum hysteresis band (VHB) of 100mV. This method avoids external feedback paths and provides faster, lower-current hysteresis than conventional positive-feedback configurations.

Does the MAX971CPA require external bypass capacitors, and what is the recommended layout practice for the REF pin?

No external bypass capacitor is required on V+ for the MAX971CPA if supply impedance is low; however, a 100nF ceramic capacitor is recommended for high-impedance or long-trace supplies. Critically, the REF pin must NOT be bypassed - doing so degrades reference stability and increases noise. Keep REF traces short and isolated from noisy signals (especially OUT) to prevent crosstalk-induced 1mV peak-to-peak reference noise.

What is the absolute maximum output voltage rating for the MAX971CPA, and how does it behave when V+ is unpowered?

The MAX971CPA output supports up to 11V above V−, with absolute maximum rating of (GND − 0.3V) to +12V. Importantly, the output transistor remains functional even when V+ is unpowered - enabling level-shifting applications where the output domain is active independently (e.g., translating signals from a powered subsystem to an unpowered microcontroller I/O line). This behavior is enabled by the separate GND pin for the output stage.