Analog Devices Inc./Maxim Integrated MAX6389XS16D3+T

Overview

MAX6389XS16D3+T from Maxim Integrated is a low-power, open-drain active-low microprocessor supervisory circuit with factory-set 1.58V reset threshold, 140ms minimum VCC reset timeout, and auxiliary RESET IN input for dual-voltage monitoring. It operates from +1.0V to +5.5V supply, consumes only 3μA at +1.8V, and guarantees valid reset output down to VCC = 1V. Used in battery-powered instrumentation and dual-rail embedded systems requiring precise brownout detection.

For engineers reviewing the MAX6389XS16D3+T datasheet, MAX6389XS16D3+T pinout, MAX6389XS16D3+T application, or MAX6389XS16D3+T equivalent, key selection criteria include its 1.58V ±2.5% threshold accuracy over –40°C to +125°C, open-drain output requiring external pullup, RESET IN comparator referenced to +1.27V, and compatibility with resistor-divider–based secondary voltage monitoring.

Technical Context

The MAX6389XS16D3+T integrates a precision bandgap reference and comparator to monitor VCC against a fixed 1.58V threshold while simultaneously comparing an external voltage at RESET IN to an internal +1.27V reference. Reset asserts if either monitored voltage falls below its respective threshold.

Its internal timer ensures a guaranteed minimum 140ms reset assertion after VCC recovers above 1.58V, and it features negative-going VCC transient immunity up to 35µs for 100mV overdrive. The open-drain RESET output supports wired-OR configurations and level-shifting across voltage domains.

Key Specifications

Pinout & Package

MAX6389XS16D3+T is housed in a RoHS-compliant 4-pin SC70 package (outline 21-0098), measuring 2.0mm × 2.1mm × 0.95mm, with 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 MAX6389XS16D3+T, MAX6387XS16D3+T eliminates external pullup needs but sacrifices bus-sharing capability, while TLV809K33DBZR reduces cost and footprint but abandons dual-supply supervision and low-voltage operation-making MAX6389XS16D3+T uniquely suited for compact, multi-rail, battery-constrained designs.

Availability

MAX6389XS16D3+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and dual-voltage IoT gateways requiring stable component supply across extended temperature and low-power constraints.

Supply support for MAX6389XS16D3+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, emphasizing low power, high reliability, and integration.

The MAX6381–MAX6390 family delivers single/dual-voltage microprocessor supervisors optimized for ultra-low quiescent current, wide temperature operation, and flexible reset architectures-including open-drain, push-pull, and manual reset variants.

FAQ

What is the exact reset threshold voltage of MAX6389XS16D3+T and how stable is it over temperature?

The MAX6389XS16D3+T has a factory-set reset threshold of 1.58V, with guaranteed accuracy of ±2.5% over the full –40°C to +125°C operating range. Its temperature coefficient is 60ppm/°C, resulting in maximum drift of ±31.6mV across the temperature span. This stability ensures reliable brownout detection in automotive and industrial environments where ambient temperature varies widely.

Does MAX6389XS16D3+T support monitoring two independent power rails-and how is the second rail configured?

Yes, MAX6389XS16D3+T supports dual-rail supervision: VCC is monitored against the fixed 1.58V threshold, while the RESET IN pin compares an external voltage to an internal +1.27V reference. To set a custom threshold (e.g., 2.5V), connect a resistor divider between the secondary rail and GND, with the midpoint fed to RESET IN-using R1 = R2 × ((V_INTH/1.27V) − 1) per the datasheet equation.

What is the minimum supply voltage at which MAX6389XS16D3+T guarantees correct RESET output logic state?

MAX6389XS16D3+T guarantees valid RESET output behavior down to VCC = 1.0V. Below this, the internal comparator and timer may not operate reliably. For applications requiring reset assertion all the way to 0V, external pullup/pulldown resistors are needed-but note that MAX6389XS16D3+T's open-drain output does not support pulldown schemes used with push-pull variants.

Can MAX6389XS16D3+T replace MAX809 or MAX6326 in existing designs-and what layout changes are required?

MAX6389XS16D3+T is pin-compatible with MAX809/MAX6326 in the 4-pin SC70 package and shares identical pinout (VCC, RESET, GND, RESET IN). However, MAX809 lacks RESET IN functionality and uses a fixed 3.08V threshold, so replacement requires verifying that 1.58V threshold and auxiliary monitoring align with system requirements-and confirming external pullup resistor value matches open-drain drive strength.

What is the maximum sink current capability of the open-drain RESET output in MAX6389XS16D3+T?

The open-drain RESET output of MAX6389XS16D3+T can sink up to 3.2mA when VCC ≥ 4.5V and RESET is asserted, with VOL ≤ 0.4V. At lower VCC levels, sink capability scales: 1.2mA at VCC ≥ 2.5V (VOL ≤ 0.3V) and 80µA at VCC ≥ 1.0V (VOL ≤ 0.3V). External pullup selection must ensure logic-low voltage stays within host μP's V_IL spec under worst-case sink current.