Analog Devices Inc./Maxim Integrated MAX6731UTTD3+T

Overview

The MAX6731UTTD3+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), features 140ms–280ms reset timeout (D3 option), operates from +0.8V to +5.5V, draws 10µA typical supply current at +3.6V, and is used in embedded systems requiring reliable power-on reset and watchdog protection during boot and runtime.

For engineers reviewing the MAX6731UTTD3+T datasheet, MAX6731UTTD3+T pinout, MAX6731UTTD3+T application, or MAX6731UTTD3+T equivalent, key selection criteria include its fixed VCC1 reset threshold (+4.375V), push-pull RST/WDO outputs, manual reset capability, 140ms minimum reset timeout, and SOT23-6 package compatibility with space-constrained industrial and telecom designs.

Technical Context

The MAX6731UTTD3+T implements a dual-mode watchdog timer: a 35s minimum startup delay after reset enables full system initialization, followed by a 1.12s minimum normal-mode timeout for rapid fault detection. Its reset logic asserts RST low when VCC1 drops below +4.250V (min) or +4.500V (max), with 0.5% hysteresis and guaranteed validity down to VCC1 = +0.8V.

It uses an internal 50kΩ pullup on MR and supports TTL/CMOS-level manual reset triggering with 1µs minimum pulse width and 100ns glitch rejection. The push-pull RST output drives high to 0.8×VCC1 (at 200µA) and low to 0.3V (at 1µA), eliminating external pullup requirements unlike open-drain variants.

Key Specifications

Pinout & Package

SOT23-6 package: 2.9mm × 1.6mm × 1.1mm body, gull-wing leads, JEDEC MO-178AC compliant, thermal resistance θJA = 230°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6730UTTD3+T and TPS3808G33DBVR, the MAX6731UTTD3+T uniquely combines push-pull RST/WDO, manual reset, and +4.375V threshold in SOT23-6-enabling compact, self-contained supervision without external components or feature trade-offs.

Availability

MAX6731UTTD3+T is available at Aetrix Electronics and suitable for industrial PLC controllers, telecom line cards, embedded medical devices, network attached storage systems, and portable instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6731UTTD3+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, mixed-signal, and power management ICs for industrial, automotive, communications, and computing markets.

The MAX6730–MAX6735 family delivers single/dual/triple-voltage microprocessor supervisors with integrated watchdog timers and manual reset, targeting high-reliability embedded systems where deterministic power-on reset and runtime fault recovery are critical.

FAQ

What is the exact VCC1 reset threshold voltage range for MAX6731UTTD3+T?

The MAX6731UTTD3+T has a factory-set VCC1 reset threshold of +4.375V nominal, with a guaranteed range of +4.250V (minimum) to +4.500V (maximum) under specified operating conditions. This threshold applies specifically to the "MR" suffix in the part number and is validated over the full -40°C to +85°C temperature range with 20ppm/°C tempco and 0.5% hysteresis referenced to typical threshold.

Does MAX6731UTTD3+T support manual reset functionality?

Yes, MAX6731UTTD3+T includes an active-low manual reset input (MR) with internal 50kΩ pullup to VCC1. Driving MR low forces immediate RST assertion for the full reset timeout period (140–280ms). It accepts standard TTL/CMOS logic levels (VIH ≥ 0.7×VCC1, VIL ≤ 0.3×VCC1), tolerates 100ns glitches, and requires only a 1µs minimum pulse width-enabling direct connection to pushbuttons or control logic without external conditioning.

What are the watchdog timer timing characteristics of MAX6731UTTD3+T?

The MAX6731UTTD3+T features a dual-mode watchdog timer: a 35s minimum startup delay after any reset event (power-up, brownout, or MR assertion), followed by a 1.12s minimum normal-mode timeout. WDI edge detection clears the timer; absence of rising/falling transitions within the timeout asserts WDO low. Leaving WDI unconnected requires a 100kΩ pull-down to ground to prevent spurious timeouts.

How does the push-pull RST output of MAX6731UTTD3+T differ from open-drain alternatives?

The MAX6731UTTD3+T's push-pull RST output actively drives both high (to 0.8×VCC1 at 200µA) and low (to 0.3V at 1µA), eliminating the need for external pullup resistors required by open-drain variants like MAX6730UTTD3+T. This simplifies PCB layout, improves rise/fall times, avoids voltage translation issues, and enables direct interfacing to μP reset pins without contention risk-provided the target μP does not drive the line bidirectionally without series resistance.

What package type and footprint does MAX6731UTTD3+T use?

MAX6731UTTD3+T is housed in a 6-pin SOT23 package (outline MO-178AC), measuring 2.9mm × 1.6mm × 1.1mm with gull-wing leads. Its land pattern matches JEDEC standard 90-0175, and it features θJA = 230°C/W. This compact, surface-mount package supports high-density layouts in space-constrained applications such as telecom modules and portable medical devices.