Analog Devices Inc./Maxim Integrated MAX6389XS32D2+T

Overview

The MAX6389XS32D2+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 3.20V VCC reset threshold (±2.5% over -40°C to +125°C), 20ms minimum reset timeout, and auxiliary RESET IN input for dual-voltage monitoring in battery-powered or industrial embedded systems.

For engineers reviewing the MAX6389XS32D2+T datasheet, MAX6389XS32D2+T pinout, MAX6389XS32D2+T application, or MAX6389XS32D2+T equivalent, key selection criteria include its 3.20V threshold accuracy, 20ms reset delay, open-drain output requiring external pullup, RESET IN comparator referenced to +1.27V, and operation down to VCC = 1.0V with guaranteed logic state validity.

Technical Context

The MAX6389XS32D2+T implements a precision bandgap-based voltage monitor for VCC and a separate high-impedance comparator for the RESET IN pin, both feeding into an internal timer that enforces a fixed 20ms reset assertion period after any threshold violation. Its open-drain RESET output requires an external pullup resistor and guarantees valid logic levels down to VCC = 1.0V.

It supports dual-supply monitoring by allowing RESET IN to be configured via an external resistor divider to detect a second voltage rail - e.g., core or I/O supply - with reset asserting if either VCC < 3.20V or RESET IN < 1.27V. The device consumes only 3μA at +1.8V and operates across -40°C to +125°C.

Key Specifications

Pinout & Package

MAX6389XS32D2+T is housed in a 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 2.0mm × 2.1mm × 0.95mm, with RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389XS32D2+T, the μDFN variant offers improved thermal handling but increases board area, while the TPS3808G32DBVR sacrifices dual-supply monitoring and ultra-low 1.8V current for TI ecosystem alignment and slightly lower typical current at 3.3V.

Availability

MAX6389XS32D2+T is available at Aetrix Electronics and suitable for portable/battery-powered equipment, dual voltage systems, industrial sensor nodes, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for MAX6389XS32D2+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 industrial, automotive, communications, and computing markets, emphasizing low power, high reliability, and integration.

The MAX6381–MAX6390 family delivers single/dual low-voltage microprocessor reset circuits optimized for battery life, wide temperature operation, and compact packaging in SC70 and μDFN formats.

FAQ

What is the exact reset threshold voltage of the MAX6389XS32D2+T and how stable is it over temperature?

The MAX6389XS32D2+T has a factory-set nominal VCC reset threshold of 3.20V, with guaranteed accuracy of ±2.5% over the full operating temperature range of -40°C to +125°C. This stability is achieved using a precision bandgap reference and trimmed comparator, ensuring consistent brownout detection across automotive and industrial environments. The MAX6389XS32D2+T maintains this tolerance without external calibration.

Does the MAX6389XS32D2+T support monitoring of a second voltage rail, and how is it implemented?

Yes, the MAX6389XS32D2+T supports dual-rail supervision via its dedicated RESET IN pin, which compares an external voltage to an internal +1.27V reference. To monitor a second rail (e.g., 1.8V), connect a resistor divider between that rail and GND, with the midpoint fed to RESET IN. The MAX6389XS32D2+T asserts reset if either VCC falls below 3.20V or the divided voltage drops below 1.27V - enabling coordinated reset without extra components.

What type of reset output does the MAX6389XS32D2+T provide, and what external components are required?

The MAX6389XS32D2+T features an open-drain active-low RESET output, requiring an external pullup resistor to the host system's logic voltage (e.g., 3.3V or 5V). No pullup is integrated internally. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements. This configuration allows multiple devices to share a common reset line - a key advantage in multi-IC systems where the MAX6389XS32D2+T serves as one supervisor among several.

What is the minimum supply voltage at which the MAX6389XS32D2+T guarantees correct reset output logic states?

The MAX6389XS32D2+T guarantees valid RESET output logic states down to VCC = 1.0V, meaning the open-drain output will correctly assert (pull low) or release (go high-impedance) even during severe brownout conditions. This specification ensures fail-safe behavior in applications where power may collapse gradually, such as battery-powered devices nearing end-of-life. The MAX6389XS32D2+T achieves this through robust internal biasing and comparator design, independent of external pullup voltage.

Is the MAX6389XS32D2+T qualified for automotive applications, and what evidence supports this?

The MAX6389XS32D2+T itself is not automotive-qualified; however, the identical function is available in the /V variant (e.g., MAX6389XS32D2/V+T), which is explicitly AEC-Q100 qualified for Grade 1 (-40°C to +125°C). The datasheet confirms AEC-Q100 qualification applies to /V-trim versions, and the MAX6389XS32D2+T shares the same die, process (BiCMOS), and electrical specifications - differing only in screening and packaging. For automotive use, specify the /V suffix version to ensure compliance.