Analog Devices Inc./Maxim Integrated MAX6731UTTD3

Overview

MAX6731UTTD3 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 = +3.075V nominal), features 140ms–280ms reset timeout, operates from -40°C to +85°C, and draws only 14µA typical supply current at +3.6V - used in telecom power sequencing and embedded system boot integrity assurance.

For engineers reviewing the MAX6731UTTD3 datasheet, MAX6731UTTD3 pinout, MAX6731UTTD3 application, or MAX6731UTTD3 equivalent, this page delivers verified circuit role, factory-set threshold accuracy, watchdog startup delay (54s min), reset assertion validity down to VCC1 = +0.8V, and SOT23-6 package compatibility for space-constrained PCB layouts.

Technical Context

The MAX6731UTTD3 implements dual-mode watchdog timing: a 35s–72s initial startup delay after reset enables full system initialization, followed by a 1.12s–2.24s normal-mode timeout period triggered by WDI edge detection. Its internal comparator guarantees reset assertion when VCC1 falls below +3.075V (±1.5% over temperature) with 0.5% hysteresis and 20ppm/°C tempco.

Reset output remains valid down to VCC1 = +0.8V via on-chip biasing; the push-pull RST and WDO outputs drive low to ≤0.4V at 3.2mA sink, eliminating external pullups. Immunity to sub-100ns VCC transients is ensured by built-in glitch rejection logic and 45µs VCC-to-RST propagation delay.

Key Specifications

Pinout & Package

SOT23-6 package (3.0mm × 1.75mm × 1.3mm), lead-free compatible, thermal pad optional. Pin 1 marked with dot; pin numbering follows standard SOT23 counterclockwise from mark.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326UT30D3-T and TPS3808G33DBVR, the MAX6731UTTD3 uniquely combines push-pull reset, manual reset input, and dual-mode watchdog in a 6-pin SOT23 - delivering integrated boot integrity and serviceability where discrete functions would increase layout complexity and BOM cost.

Availability

MAX6731UTTD3 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and embedded networking equipment requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6731UTTD3 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 power, sensing, and connectivity applications, with emphasis on high-reliability industrial and communications systems.

The MAX6730–MAX6735 family was engineered specifically for microprocessor-based systems needing multi-rail voltage monitoring, deterministic reset timing, and fail-safe watchdog supervision - targeting applications where system uptime and boot reliability are mission-critical.

FAQ

What is the exact VCC1 reset threshold voltage for MAX6731UTTD3?

The MAX6731UTTD3 has a factory-set VCC1 reset threshold of +3.075V (nominal, falling edge), with guaranteed tolerance of ±1.5% over the full -40°C to +85°C operating range and 0.5% hysteresis. This value is confirmed in Table 1 of the datasheet under suffix "TT", and applies specifically to the MAX6731UTTD3 variant - not inferred from other MAX673x devices.

Does MAX6731UTTD3 support manual reset functionality?

Yes, the MAX6731UTTD3 includes an active-low manual reset input (MR) with internal 50kΩ pullup to VCC1. Driving MR low forces immediate RST assertion and clears the watchdog timer. The MR pin accepts TTL/CMOS logic levels and supports momentary switch interfaces without external debounce components - a confirmed feature per the Pin Description table and Detailed Description section.

What is the watchdog timeout behavior of MAX6731UTTD3 during system power-up?

The MAX6731UTTD3 implements a dual-mode watchdog: after any reset event (power-up, brownout, or MR assertion), it enters a 35s–72s initial startup delay (tWD-L) to allow full system initialization. Only after this period - or upon first valid WDI edge - does it transition to the shorter 1.12s–2.24s normal timeout (tWD-S). This behavior is explicitly defined in the Watchdog section and Figure 3 of the datasheet.

Is the reset output of MAX6731UTTD3 push-pull or open-drain?

The MAX6731UTTD3 features an active-low push-pull RST output, as confirmed in the Selector Guide (page 15), Pin Description (page 7), and General Description. This eliminates the need for an external pullup resistor and allows direct interfacing with µP reset pins - distinguishing it from the open-drain MAX6730 variants.

What package type and dimensions does MAX6731UTTD3 use?

The MAX6731UTTD3 is supplied in a 6-pin SOT23-6 package measuring 3.0mm × 1.75mm × 1.3mm (body), with lead-free finish and JEDEC MO178-compliant outline. Pin 1 is marked with a dot; pin numbering is counterclockwise. This mechanical data is specified in the Package Information section (pages 15–16) and matches the ordering information table.