Analog Devices Inc./Maxim Integrated MAX6389LT44D3+T

Overview

The MAX6389LT44D3+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 4.38V reset threshold (±2.5% over -40°C to +125°C), 140ms minimum VCC reset timeout, and auxiliary RESET IN input for dual-voltage monitoring. It operates from 1.0V to 5.5V supply and consumes only 3μA at 1.8V, enabling use in battery-powered systems requiring reliable power-on reset and brownout detection.

For engineers reviewing the MAX6389LT44D3+T datasheet, MAX6389LT44D3+T pinout, MAX6389LT44D3+T application, or MAX6389LT44D3+T equivalent, key selection criteria include its open-drain reset architecture, dual-supply monitoring capability via RESET IN, guaranteed reset validity down to VCC = 1V, and AEC-Q100-qualified 4-pin SC70 package compatibility with space-constrained industrial and automotive control modules.

Technical Context

The MAX6389LT44D3+T integrates a precision voltage comparator monitoring VCC against a fixed 4.38V threshold and a separate high-impedance RESET IN input referenced to an internal 1.27V bandgap. When either VCC or RESET IN falls below its respective threshold, the open-drain RESET output pulls low for ≥140ms after recovery - ensuring stable μP initialization during power transients or secondary rail faults.

Its auxiliary RESET IN comparator supports user-defined thresholds via external resistor dividers (e.g., 100kΩ R1 + 100kΩ R2 yields ~2.54V trip point), while negative-going VCC transient immunity up to 35µs at 100mV overdrive prevents false resets in noisy environments. The device guarantees correct logic state for VCC ≥ 1V without external biasing.

Key Specifications

Pinout & Package

MAX6389LT44D3+T uses a RoHS-compliant 4-pin SC70 package (outline 21-0098, land pattern 90-0187) with 0.65mm pitch and thermal resistance θ_JA = 322.6°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6389XS44D3+T and TLV809K33DBZR, the MAX6389LT44D3+T uniquely supports dual-voltage supervision in a compact 4-pin SC70 package while maintaining ultra-low 3μA quiescent current - making it irreplaceable in space-limited automotive and industrial modules requiring coordinated reset of multiple power domains.

Availability

MAX6389LT44D3+T is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, portable medical sensors, and battery-powered data loggers requiring stable component supply with AEC-Q100 qualification and long-term lifecycle support.

Supply support for MAX6389LT44D3+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, and computing applications, with emphasis on power management, sensing, and interface solutions.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy microprocessor supervisory circuits targeting space-constrained and battery-operated systems requiring dual-rail monitoring and guaranteed reset behavior across extended temperature ranges.

FAQ

What is the exact reset threshold voltage of the MAX6389LT44D3+T?

The MAX6389LT44D3+T has a factory-set nominal reset threshold of 4.38V, with tolerance of ±2.5% over the full operating temperature range (-40°C to +125°C). This value is derived from the "44" suffix in the part number, corresponding to the 4.27V/4.38V/4.48V min/nom/max range specified in the Reset Thresholds table. The threshold is internally trimmed and does not require external calibration.

Does the MAX6389LT44D3+T support monitoring two different power rails simultaneously?

Yes, the MAX6389LT44D3+T supports dual-rail monitoring via its dedicated RESET IN pin, which compares an external voltage to an internal 1.27V reference. When either VCC drops below 4.38V or the voltage at RESET IN falls below its calculated threshold (set by external resistors), the open-drain RESET output asserts. This eliminates the need for a second supervisor IC in systems with core and I/O supplies.

What is the function of the RESET IN pin on the MAX6389LT44D3+T?

The RESET IN pin on the MAX6389LT44D3+T is a high-impedance input to a dedicated comparator referenced to an internal 1.27V bandgap. It allows users to monitor a second voltage rail (e.g., 3.3V or 5V) by connecting an external resistor divider. Reset asserts if either VCC < 4.38V or RESET IN < 1.27V × (R1/R2 + 1), enabling flexible dual-supply supervision without additional components.

Can the MAX6389LT44D3+T operate reliably at very low supply voltages?

Yes, the MAX6389LT44D3+T guarantees correct RESET output logic state down to VCC = 1.0V, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Its internal circuitry remains functional and the open-drain RESET output maintains defined behavior throughout this range - critical for brownout recovery in battery-powered systems where supply voltage decays gradually.

Is the MAX6389LT44D3+T qualified for automotive applications?

The MAX6389LT44D3+T is not explicitly marked with the /V automotive qualification suffix in its ordering code, and the provided documentation confirms AEC-Q100 qualification applies only to specific /V-trim versions (e.g., MAX6389XS30D2/V+T). Therefore, standard MAX6389LT44D3+T is intended for industrial and commercial applications, not automotive-grade deployment unless separately validated and certified.