Analog Devices Inc./Maxim Integrated MAX6731UTSD3+T

Overview

MAX6731UTSD3+T from Maxim Integrated is a single-voltage microprocessor supervisor IC with push-pull active-low reset output, manual reset input, and independent push-pull watchdog output. It monitors one fixed supply (VCC1 = +4.375V nominal threshold), provides 140ms–280ms reset timeout, consumes 14µA typical supply current, and operates from -40°C to +85°C in SOT23-6 package for embedded power sequencing and system reliability in space-constrained applications.

For engineers reviewing the MAX6731UTSD3+T datasheet, MAX6731UTSD3+T pinout, MAX6731UTSD3+T application, or MAX6731UTSD3+T equivalent, key selection criteria include its factory-set +4.375V VCC1 reset threshold, push-pull RST/WDO outputs eliminating external pullups, 140ms minimum reset timeout (D3 suffix), manual reset capability, and immunity to sub-100ns VCC transients - critical for stable boot in telecom and industrial control systems.

Technical Context

The MAX6731UTSD3+T integrates a precision voltage monitor for VCC1 with ±1.25% threshold accuracy over temperature, a 140ms–280ms programmable reset timeout timer, and a dual-mode watchdog: 35s startup delay after reset followed by 1.12s normal-mode timeout. Its push-pull RST and WDO outputs drive logic directly without pullup resistors, simplifying interface to µP reset and NMI pins.

It features a 50kΩ internal MR pullup, 100ns MR glitch rejection, and guaranteed reset assertion down to VCC1 = +0.8V. The device uses BiCMOS process for low 14µA supply current at +3.6V and operates across full industrial temperature range (-40°C to +85°C) with 20ppm/°C reset threshold tempco.

Key Specifications

Pinout & Package

SOT23-6 package: 1.6mm × 2.9mm × 1.1mm body, gull-wing leads, RoHS-compliant lead(Pb)-free finish (+T suffix).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisor applications.

Compared with MAX6730UTSD3+T and TPS3808G33DBVR, the MAX6731UTSD3+T uniquely delivers push-pull RST/WDO, integrated MR, and precise +4.375V threshold in identical SOT23-6 packaging - enabling drop-in replacement where active-drive reset and watchdog signaling are mandatory.

Availability

MAX6731UTSD3+T is available at Aetrix Electronics and suitable for industrial control systems, telecom infrastructure equipment, and portable medical devices requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6731UTSD3+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, communications, and computing markets, with emphasis on high-reliability power management and supervisory solutions.

The MAX6730–MAX6735 family was engineered for robust system-level power monitoring in space-constrained embedded applications, delivering integrated voltage supervision, watchdog timing, and manual reset in ultra-small packages.

FAQ

What is the exact VCC1 reset threshold voltage for MAX6731UTSD3+T?

The MAX6731UTSD3+T has a factory-set VCC1 reset threshold of +4.375V (MR suffix), with guaranteed limits of +4.250V (min) and +4.500V (max) over -40°C to +85°C. This threshold is laser-trimmed during production and does not require external components. The MAX6731UTSD3+T uses this fixed point to supervise 3.3V or 5V supply rails with margin against ripple and dropout.

Does MAX6731UTSD3+T support manual reset functionality?

Yes, the MAX6731UTSD3+T includes an active-low manual reset input (MR) with a built-in 50kΩ pullup resistor to VCC1. Driving MR low forces RST assertion for the full reset timeout period (140–280ms), clearing the watchdog timer and deasserting WDO. The MAX6731UTSD3+T requires no external components for basic manual reset - a momentary switch from MR to GND suffices.

What are the watchdog timeout periods for MAX6731UTSD3+T?

The MAX6731UTSD3+T implements a dual-mode watchdog: a 35-second minimum startup delay after any reset event (power-up, brownout, or MR assertion), followed by a 1.12-second minimum normal-mode timeout. The watchdog timer clears on every rising or falling edge at WDI. The MAX6731UTSD3+T guarantees these values across temperature and supply voltage per its Electrical Characteristics table.

Is MAX6731UTSD3+T compatible with bidirectional µP reset pins?

Yes, but requires a 10kΩ series resistor between RST and the µP's bidirectional reset I/O port to prevent logic contention. The MAX6731UTSD3+T's push-pull RST output actively drives high/low, unlike open-drain alternatives. Without the resistor, simultaneous drive from both devices could cause excessive current or undefined logic states. This configuration is documented in Maxim's Application Note for interfacing with bidirectional reset pins.

What package type and dimensions does MAX6731UTSD3+T use?

The MAX6731UTSD3+T uses a RoHS-compliant lead(Pb)-free SOT23-6 package (package code U6+1), measuring 1.6mm × 2.9mm × 1.1mm with 0.95mm lead pitch. Its pinout matches JEDEC MO-178AB, and it supports standard reflow soldering profiles. The MAX6731UTSD3+T shares footprint compatibility with other SOT23-6 supervisors like TPS3808 series, though pin functions differ.