Analog Devices Inc./Maxim Integrated MAX6339BUT+T

Overview

MAX6339BUT+T from Maxim Integrated is a precision quad voltage supervisory IC that monitors +5.0V (−5% threshold), +3.3V (−5%), +2.5V (−5%), and one user-adjustable input (1.23V internal reference) in multi-rail systems. It delivers 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 telecom and industrial equipment for reliable power-up/power-down sequencing.

For engineers reviewing the MAX6339BUT+T datasheet, MAX6339BUT+T pinout, MAX6339BUT+T application, or MAX6339BUT+T equivalent, key selection considerations include factory-trimmed −5% thresholds across three fixed rails, adjustable fourth input compatibility, guaranteed operation down to IN1/IN2 = 1V, immunity to short transients, and SOT23-6 footprint constraints.

Technical Context

The MAX6339BUT+T integrates four independent voltage comparators with a shared 1.23V bandgap reference and internal resistor-divider networks calibrated for precise −5% undervoltage detection on +5.0V, +3.3V, and +2.5V rails. Its reset logic uses a NOR-gated output that asserts RESET low upon any threshold violation and holds for ≥140ms after all inputs recover.

Power is derived solely from IN2, which also serves as the internal pullup source for the open-drain RESET output (10µA typ). Input hysteresis is fixed at 0.3% of threshold voltage, and transient immunity is validated up to 1000µs for overdrive ≥50mV - critical for noisy industrial power environments.

Key Specifications

Pinout & Package

The MAX6339BUT+T 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 finish (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6340BUT+T and TPS3307-33DGNR, the MAX6339BUT+T uniquely balances quad-rail coverage, −5% precision, and adjustable threshold capability in a minimal SOT23-6 footprint-making it optimal for space-constrained industrial and telecom systems requiring exactly four monitored supplies without watchdog overhead.

Availability

MAX6339BUT+T is available at Aetrix Electronics and suitable for telecommunications infrastructure, industrial PLC controllers, and network switch ASIC power sequencing requiring stable component supply and long-term industrial temperature support.

Supply support for MAX6339BUT+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The MAX6339 series was designed specifically for compact, multi-rail power supervision in space-constrained embedded systems-delivering precision voltage monitoring, robust reset timing, and minimal external component requirements.

FAQ

What voltage rails does the MAX6339BUT+T monitor?

The MAX6339BUT+T monitors +5.0V (−5% threshold), +3.3V (−5%), +2.5V (−5%), and one user-adjustable input referenced to 1.23V. These settings are factory-trimmed and encoded in the part number; no external resistors are needed for the three fixed rails. The MAX6339BUT+T's IN4 pin accepts an external resistor divider to set custom thresholds, enabling flexibility beyond standard supply voltages.

How does the RESET output behave during power failure?

The MAX6339BUT+T asserts its open-drain RESET output low whenever any monitored input falls below its threshold, and holds RESET low for a minimum of 140ms after all inputs recover above their thresholds. Crucially, RESET remains valid as long as either IN1 or IN2 stays above 1.0V-ensuring supervision continues even during deep brownout conditions where other ICs may lose functionality. The internal 10µA pullup to IN2 eliminates need for external pullup in many cases.

Can unused inputs be left floating on the MAX6339BUT+T?

No. Unused inputs on the MAX6339BUT+T must not be left floating or tied to ground. For positive-threshold inputs (IN1, IN3, IN4 with adjustable option), tie them to a supply voltage greater in magnitude than their specified threshold-typically to IN2. For negative-threshold variants (not applicable to MAX6339BUT+T), unused IN4 would require connection to a more negative supply. This prevents erroneous reset assertion and ensures comparator stability.

What is the supply current consumption of the MAX6339BUT+T?

The MAX6339BUT+T consumes 55µA typical supply current when powered from IN2 across the full −40°C to +85°C range. This low quiescent draw is achieved through BiCMOS process optimization and dynamic biasing. The current splits between internal circuitry (~30µA) and the resistor-divider network for monitored rails (~25µA), making it suitable for battery-backed or always-on supervisory paths without impacting system standby efficiency.

Is the MAX6339BUT+T compatible with lead-free assembly processes?

Yes. The MAX6339BUT+T carries the "+T" suffix, indicating RoHS-compliant, lead-free packaging with matte tin plating and qualification for standard Pb-free reflow profiles (per JEDEC J-STD-020). It supports peak reflow temperatures up to +260°C and is shipped in tape-and-reel format with a 2500-piece minimum order quantity-fully aligned with modern electronics manufacturing requirements.