Analog Devices Inc./Maxim Integrated MAX6339FUT+T

Overview

MAX6339FUT+T from Maxim Integrated is a precision 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 a single 6-pin SOT23 package. It asserts a single active-low open-drain RESET output when any monitored supply falls below its threshold, with guaranteed operation down to IN1 or IN2 ≥ 1V and a minimum 140ms reset timeout. It targets multi-rail embedded systems requiring compact, low-power power-good monitoring.

For engineers reviewing the MAX6339FUT+T datasheet, MAX6339FUT+T pinout, MAX6339FUT+T application, or MAX6339FUT+T equivalent, key selection criteria include factory-trimmed −5% thresholds for 5V/3V/2.5V rails, 55µA typical supply current, immunity to short transients (<1µs at 50mV overdrive), and compatibility with mixed-voltage logic interfaces via internal 10µA pullup to IN2.

Technical Context

The MAX6339FUT+T integrates four independent comparators with a shared 1.23V bandgap reference and factory-laser-trimmed resistor-divider networks for fixed thresholds on IN1 (+5.0V), IN2 (+3.0V), and IN3 (+2.5V), all with −5% tolerance. The fourth input (IN4) connects directly to the reference, enabling user-defined thresholds via external resistor dividers.

Its reset logic uses a NOR-gated output stage with built-in 140ms minimum timeout counter and 0.3% threshold hysteresis per channel. The device draws power solely from IN2, and RESET remains valid as long as IN1 ≥ 1V or IN2 ≥ 1V - critical for brownout detection during partial rail collapse.

Key Specifications

Pinout & Package

MAX6339FUT+T is housed in a 6-pin SOT23-6 package (2.9mm × 1.6mm × 1.1mm), optimized for space-constrained PCB layouts and reflow-compatible assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6340FUT+T and TPS3307-33D, the MAX6339FUT+T uniquely delivers quad monitoring with one adjustable input in SOT23-6, making it optimal for space-constrained designs needing four-rail coverage without watchdog overhead or external components.

Availability

MAX6339FUT+T is available at Aetrix Electronics and suitable for telecommunications infrastructure, industrial PLCs, network-attached storage, and high-end multifunction printers requiring stable component supply and long-term industrial temperature support.

Supply support for MAX6339FUT+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 MAX6339FUT+T belongs to Maxim's µP supervisory product line, designed specifically for compact, low-power, multi-rail voltage monitoring in space- and power-sensitive embedded systems.

FAQ

What is the exact threshold voltage range for the +3.0V input on MAX6339FUT+T?

The +3.0V input (IN2) on MAX6339FUT+T has a factory-trimmed −5% threshold range of 2.55V to 2.70V. This is specified in the Electrical Characteristics table under "+3.0V (−5%) threshold" with MIN = 2.55V, TYP = 2.63V, and MAX = 2.70V. The device asserts RESET when IN2 drops below this range, and the threshold is guaranteed over the full −40°C to +85°C operating temperature range. MAX6339FUT+T uses this same IN2 pin as its power supply source.

Can MAX6339FUT+T monitor a −12V supply, and if so, how?

MAX6339FUT+T does not natively support −12V monitoring, as its fixed negative option is only −5V. However, it can monitor −12V using an external resistor divider on IN4 (the adjustable input). Per the datasheet Figure 5, a two-resistor network scales −12V down to match the internal 1.23V reference. For −12V nominal with −11.1V threshold, R1 = 3.48kΩ and R2 = 2.49kΩ yields <1% error. MAX6339FUT+T's IN4 input accepts this scaled voltage while maintaining full comparator accuracy.

Is an external pullup resistor required for the RESET output of MAX6339FUT+T?

No external pullup resistor is required for MAX6339FUT+T when interfacing with logic powered by the same IN2 supply (e.g., 3.0V), because it includes a 10µA internal pullup to IN2. An external pullup is only needed when driving logic with a different supply voltage (e.g., 5V or 1.8V), and must be sized to overdrive the internal pullup without exceeding 20mA sink current. MAX6339FUT+T's RESET pin is open-drain and fully compatible with mixed-voltage systems.

What is the minimum valid supply voltage for MAX6339FUT+T to maintain RESET output integrity?

MAX6339FUT+T guarantees correct RESET output state as long as either IN1 ≥ 1.0V or IN2 ≥ 1.0V. This is explicitly stated in Note 3 of the Electrical Characteristics table and enables reliable brownout detection even when one rail collapses completely. The device continues asserting RESET until all monitored inputs recover above their thresholds and the 140ms timeout expires. MAX6339FUT+T relies on IN2 for internal power, but retains functional reset signaling down to 1V on either IN1 or IN2.

How does MAX6339FUT+T handle short-duration voltage transients on monitored inputs?

MAX6339FUT+T is designed to reject short transients: the Typical Operating Characteristics graph "MAXIMUM IN_ TRANSIENT DURATION vs. RESET THRESHOLD OVERDRIVE" shows immunity to pulses <1µs wide when overdrive is ≥50mV. This is achieved via internal filtering and comparator hysteresis (0.3% per channel), preventing false resets caused by switching noise or ESD events. MAX6339FUT+T maintains stable operation in electrically noisy environments such as motor-driven or SMPS-based systems without requiring external RC filters.