Analog Devices Inc./Maxim Integrated MAX6339FUT

Overview

The MAX6339FUT from Maxim Integrated is a quad voltage supervisory IC that monitors +5.0V (−5%), +3.0V (−5%), +2.5V (−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. Used in desktop computers and networking equipment for reliable power-on reset and brownout detection.

For engineers reviewing the MAX6339FUT datasheet, MAX6339FUT pinout, MAX6339FUT application, or MAX6339FUT equivalent, key selection considerations include its factory-trimmed −5% thresholds on three fixed inputs, adjustable fourth input, guaranteed operation down to IN1/IN2 = 1V, immunity to short transients, and SOT23-6 footprint compatibility with space-constrained embedded designs.

Technical Context

The MAX6339FUT integrates four precision comparators with an internal bandgap reference (1.23V) and factory-trimmed resistor-divider networks for fixed thresholds. Its architecture supports independent monitoring of four rails without external components-except when using the adjustable input, which requires an external resistor divider to scale voltages above 1.23V.

Reset assertion is governed by comparator hysteresis (0.3% of threshold), transient immunity (up to ~100µs glitches at 50mV overdrive), and a guaranteed 140ms–280ms timeout after all inputs recover. The open-drain RESET output features a 10µA internal pullup to IN2 and remains valid as long as IN1 ≥ 1V or IN2 ≥ 1V.

Key Specifications

Pinout & Package

The MAX6339FUT is housed in a 6-pin SOT23-6 package (JEDEC MO-178AA), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads and lead-free (RoHS-compliant) option available.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6340FUT and TPS3307-33D, the MAX6339FUT uniquely delivers quad monitoring with one adjustable input in SOT23-6, enabling full 4-rail supervision without secondary ICs-while its 140ms timeout provides faster system recovery than alternatives with longer delays.

Availability

MAX6339FUT is available at Aetrix Electronics and suitable for desktop computers, network routers, industrial PLCs, and high-end printers requiring stable component supply and long-term production continuity.

Supply support for MAX6339FUT 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, mixed-signal, and power-management ICs for demanding industrial, communications, and computing applications.

The MAX6339FUT belongs to Maxim's µP supervisory product line, engineered specifically for compact, low-power, multi-rail voltage monitoring in space-constrained embedded systems with strict reliability requirements.

FAQ

What is the exact reset timeout period specification for the MAX6339FUT?

The MAX6339FUT guarantees a minimum reset timeout period of 140ms after all monitored inputs exceed their thresholds, with a typical value of 200ms and maximum of 280ms over the full −40°C to +85°C operating range. This timeout ensures sufficient hold time for microprocessor initialization before release, and is fully characterized-not derived from external components or configuration.

Can the MAX6339FUT monitor a +1.5V supply, and how is it configured?

Yes-the MAX6339FUT can monitor a +1.5V supply using its IN4 pin, which references an internal 1.23V threshold. Configure with an external resistor divider where R1 = R2 × ((1.5V / 1.23V) − 1). For example, with R2 = 100kΩ, R1 ≈ 22kΩ. Input current error remains <1% due to guaranteed ±0.1µA IN4 bias current.

What happens to the RESET output if IN2 drops to 1.2V while IN1 remains at 4.8V?

The RESET output of the MAX6339FUT remains valid and correctly asserted because the device guarantees RESET functionality as long as either IN1 ≥ 1V or IN2 ≥ 1V. At IN2 = 1.2V, the internal 10µA pullup still operates, and the open-drain output retains proper logic levels-enabling controlled reset during partial power loss scenarios.

Does the MAX6339FUT require external bypass capacitors, and where should they be placed?

The MAX6339FUT does not require external bypass capacitors for basic operation, but for enhanced noise immunity in electrically noisy environments, place a 0.1µF ceramic capacitor between IN2 and GND. Additional 0.1µF caps may be added to IN1, IN3, and IN4 if transient rejection beyond the built-in 100µs immunity is needed-especially near switching regulators or motor drivers.

How does the MAX6339FUT handle short voltage transients on monitored inputs?

The MAX6339FUT rejects short transients on monitored inputs via built-in comparator hysteresis (0.3% of threshold) and a dedicated glitch-immunity circuit. As shown in the datasheet's MAX6339toc04 graph, it ignores transients ≤100µs in duration when overdriven by ≥50mV-preventing false resets during ESD events, relay bounce, or switching noise without requiring external RC filters.