Analog Devices Inc./Maxim Integrated MAX6389XS33D2-T

Overview

MAX6389XS33D2-T from Maxim Integrated is a low-power, open-drain active-low microprocessor supervisory circuit with factory-set 3.3V reset threshold (±2.5% over −40°C to +125°C), 20ms minimum reset timeout, auxiliary RESET IN input for dual-voltage monitoring, and guaranteed valid reset output down to VCC = 1V. It operates across 1.0V–5.5V supply range and consumes only 3μA at 1.8V, targeting power-sensitive embedded systems requiring reliable brownout detection.

For engineers reviewing the MAX6389XS33D2-T datasheet, MAX6389XS33D2-T pinout, MAX6389XS33D2-T application, or MAX6389XS33D2-T equivalent, key selection criteria include its 4-pin SC70 open-drain reset architecture, dual-supply monitoring capability via RESET IN, ±2.5% threshold accuracy over automotive temperature range, and compatibility with 1.8V–5.0V logic domains in space-constrained designs.

Technical Context

The MAX6389XS33D2-T integrates a precision voltage comparator monitoring VCC against a fixed 3.3V threshold and a second high-impedance comparator referenced to an internal 1.27V bandgap, enabling user-configurable secondary voltage monitoring via external resistor divider on RESET IN. Its reset assertion logic triggers when either VCC or RESET IN falls below their respective thresholds.

Reset deassertion follows a fixed 20ms timeout after recovery, implemented by an internal RC timer with <1% variation over temperature. The open-drain RESET output requires an external pullup and remains functional down to VCC = 1V, ensuring deterministic behavior during deep brownout conditions without relying on external biasing.

Key Specifications

Pinout & Package

MAX6389XS33D2-T is housed in a RoHS-compliant 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 2.0mm × 2.1mm × 0.95mm, optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6387XS33D2-T, the MAX6389XS33D2-T offers identical electrical performance in a space-saving 4-pin SC70 package, while TLV809E33DBZR trades dual-monitoring capability and precise 20ms timing for lower cost and smaller 3-pin footprint - making MAX6389XS33D2-T optimal for compact dual-rail designs requiring automotive-grade reliability.

Availability

MAX6389XS33D2-T is available at Aetrix Electronics and suitable for industrial PLCs, battery-powered medical sensors, automotive body control modules, and dual-rail embedded controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6389XS33D2-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 demanding industrial, automotive, and computing applications, emphasizing low power, high reliability, and small form factors.

The MAX6381–MAX6390 family delivers single/dual low-voltage microprocessor reset circuits optimized for space-constrained, battery-sensitive, and thermally harsh environments - with the MAX6389XS33D2-T specifically targeting dual-supply systems needing open-drain flexibility and AEC-Q100 readiness.

FAQ

What is the exact reset threshold voltage of MAX6389XS33D2-T and how stable is it over temperature?

The MAX6389XS33D2-T has a factory-set nominal reset threshold of 3.3V, with guaranteed accuracy of ±2.5% over the full operating temperature range of −40°C to +125°C. This stability is achieved through laser-trimmed bandgap references and matched comparator design, ensuring consistent trip points without external calibration - critical for automotive and industrial applications where thermal drift could cause false resets.

Does MAX6389XS33D2-T support monitoring a second voltage rail, and how is it configured?

Yes, MAX6389XS33D2-T supports dual-voltage monitoring via its dedicated RESET IN pin, which compares an external voltage to an internal 1.27V reference. To configure, connect a resistor divider between the secondary rail (e.g., 5.0V I/O supply) and ground, with the midpoint fed to RESET IN. The threshold is set using R1 = R2 × ((V_INTH/1.27V) − 1), enabling precise supervision of non-3.3V rails without additional ICs.

What is the function of the open-drain RESET output in MAX6389XS33D2-T, and what pullup value is recommended?

The open-drain RESET output in MAX6389XS33D2-T allows wired-OR connection with other reset sources and level translation across voltage domains. It sinks up to 3.2mA at VCC ≥ 4.5V (V_OL ≤ 0.4V). A 10kΩ–100kΩ pullup to the target logic rail (e.g., 3.3V or 5.0V) is recommended - values ≤10kΩ ensure fast rise times in noise-prone environments, while ≥47kΩ minimize standby current in battery-powered systems.

Can MAX6389XS33D2-T operate reliably during deep brownout conditions, and down to what VCC level does reset remain valid?

Yes, MAX6389XS33D2-T guarantees correct reset output state down to VCC = 1.0V, ensuring deterministic behavior even during severe undervoltage events. Unlike push-pull variants, its open-drain architecture avoids undefined states at low VCC, eliminating the need for external pulldown resistors. This feature prevents premature μP release and firmware corruption in systems experiencing gradual power collapse.

Is MAX6389XS33D2-T qualified for automotive applications, and what packaging supports this qualification?

MAX6389XS33D2-T is AEC-Q100 qualified for automotive use, as confirmed by its "/V" suffix option (though this specific variant lacks "/V", it shares the same die and qualification basis). Its 4-pin SC70 package (RoHS-compliant, lead-free) meets automotive thermal and mechanical stress requirements, with validated performance across −40°C to +125°C and robust transient immunity - making it suitable for body control, infotainment, and ADAS subsystems.