Analog Devices Inc./Maxim Integrated MAX6339HUT

Overview

MAX6339HUT from Maxim Integrated is a quad voltage supervisory IC that monitors +5.0V (−5%), +3.0V (−5%), +1.8V (−5%), and one user-adjustable input (1.23V internal reference) in multi-rail systems. It provides a single active-low open-drain RESET output with 140ms minimum timeout, operates from IN2 supply (1.0V to 5.5V), and draws only 55µA typical supply current. It is used in industrial equipment and networking gear where reliable power-up sequencing and undervoltage detection are critical.

For engineers reviewing the MAX6339HUT datasheet, MAX6339HUT pinout, MAX6339HUT application, or MAX6339HUT equivalent, key selection considerations include factory-trimmed thresholds for three fixed rails, adjustable fourth threshold via external resistor divider, guaranteed operation down to IN1 or IN2 = 1V, immunity to short transients, and SOT23-6 packaging for space-constrained designs.

Technical Context

The MAX6339HUT integrates four precision comparators with an internal bandgap reference (1.23V) and factory-trimmed resistor-divider networks for three fixed inputs (+5.0V, +3.0V, +1.8V, all −5% tolerance). The fourth input (IN4) connects directly to the comparator's reference node, enabling user-defined thresholds via external resistive dividers.

Its reset logic uses a NOR gate to assert RESET low if any monitored input falls below its threshold (or rises above for negative rails); RESET remains asserted for ≥140ms after all inputs recover. The open-drain output includes a 10µA internal pullup to IN2, eliminating need for external pullup in many 3.3V/5V logic interfaces.

Key Specifications

Pinout & Package

MAX6339HUT is housed in a 6-pin SOT23-6 package (JEDEC MO-178AA), footprint-compatible with standard SOT-23 layouts and suitable for automated placement. Package dimensions: 2.9mm × 1.6mm × 1.1mm (max height).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage supervisory applications.

Compared with TPS3307-33D and ADM1085AKSZ-REEL7, the MAX6339HUT uniquely combines three factory-set thresholds (+5V/−5%, +3V/−5%, +1.8V/−5%) with a fourth user-adjustable input in a single SOT23-6 package, offering higher rail-count density and design flexibility for heterogeneous power systems.

Availability

MAX6339HUT is available at Aetrix Electronics and suitable for industrial equipment, networking gear, high-end printers, and telecommunications infrastructure requiring stable component supply and long-term production continuity.

Supply support for MAX6339HUT 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and computing markets.

The MAX6339HUT belongs to Maxim's µP supervisory product line, designed specifically for compact, low-power, multi-rail voltage monitoring in space- and reliability-critical embedded systems.

FAQ

What voltage rails does the MAX6339HUT monitor by default?

The MAX6339HUT monitors +5.0V (−5% threshold), +3.0V (−5%), +1.8V (−5%), and one user-adjustable input referenced to 1.23V. Its Selector Guide code "H" confirms this configuration: IN1 = +5V, IN2 = +3.0V (power supply), IN3 = +1.8V, IN4 = adjustable. No external components are needed for the three fixed rails.

How is the adjustable threshold on the MAX6339HUT implemented?

The MAX6339HUT's IN4 pin connects directly to an internal 1.23V reference comparator input. To set a custom threshold (e.g., 2.5V), an external resistor divider (R1/R2) is required: V_TH = 1.23V × (R1 + R2)/R2. With ±0.1µA input bias, R2 ≤ 100kΩ maintains <1% error. This allows precise monitoring of nonstandard rails without changing the IC.

What is the minimum operating voltage for the MAX6339HUT's RESET output to remain valid?

The MAX6339HUT's RESET output remains valid (i.e., correctly asserted or deasserted) as long as either IN1 or IN2 is ≥ 1.0V. This is explicitly guaranteed in the datasheet (Note 3) and enables reliable reset signaling during deep brownout conditions where other supplies may collapse first.

Does the MAX6339HUT require an external pullup resistor on the RESET pin?

No - the MAX6339HUT includes a 10µA internal pullup to IN2, sufficient for interfacing with 3.3V or 5V logic without external components. An external pullup is only needed when driving logic with a different supply voltage (e.g., 1.8V), and even then, it overdrives the internal pullup without reverse current flow due to internal protection circuitry.

What is the guaranteed reset timeout period for the MAX6339HUT across temperature?

The MAX6339HUT guarantees a minimum reset timeout period of 140ms after all monitored voltages exceed their thresholds, valid across the full −40°C to +85°C operating range. Typical values reach 200ms, and maximum is 280ms - ensuring compliance with µP, FPGA, and ASIC boot timing requirements under worst-case conditions.