Analog Devices Inc./Maxim Integrated MAX6731UTRD3+T

Overview

MAX6731UTRD3+T from Maxim Integrated is a single-voltage microprocessor supervisor IC with active-low push-pull reset output, manual reset input, and independent watchdog timer. It monitors one fixed supply (VCC1) at factory-set +3.075V threshold, provides 140–280ms reset timeout, consumes 14µA typical supply current, and operates from -40°C to +85°C in SOT23-6 package. It is used in embedded systems requiring reliable power-on reset and software lockup protection.

For engineers reviewing the MAX6731UTRD3+T datasheet, MAX6731UTRD3+T pinout, MAX6731UTRD3+T application, or MAX6731UTRD3+T equivalent, this page delivers verified specifications, validated pin functions, confirmed thermal and timing behavior, and real-world substitution guidance - all grounded in Maxim's official documentation for the exact part number.

Technical Context

The MAX6731UTRD3+T integrates a precision voltage monitor for VCC1 (nominal +3.075V), a 140–280ms reset timeout timer, and a dual-mode watchdog with 35s startup delay and 1.12s normal timeout. Its push-pull RST output drives directly into microprocessor reset inputs without external pull-up, while its push-pull WDO enables immediate fault signaling without external components.

It features a manual reset input (MR) with internal 50kΩ pull-up, guaranteed reset validity down to VCC1 = +0.8V, and immunity to sub-100ns VCC transients. All logic thresholds scale with VCC1 (VIH = 0.7×VCC1, VIL = 0.3×VCC1), ensuring robust interface compatibility across supply voltages.

Key Specifications

Pinout & Package

SOT23-6 package (6-pin, 1.6mm × 2.9mm footprint), lead(Pb)-free, RoHS compliant, JEDEC MO-178AC standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6730UTRD3+T and TPS3808G33DBVR, the MAX6731UTRD3+T uniquely combines push-pull RST/WDO, manual reset, and dual-mode watchdog in a single SOT23-6 package - enabling compact, self-contained supervision without external components or feature compromise.

Availability

MAX6731UTRD3+T is available at Aetrix Electronics and suitable for telecom power sequencing, industrial PLC controllers, medical handheld diagnostics, and network switch management CPUs requiring stable component supply, long-lifecycle support, and guaranteed RoHS compliance.

Supply support for MAX6731UTRD3+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, computing, and communications applications, with emphasis on reliability, integration, and low-power operation.

The MAX6730–MAX6735 family was engineered specifically for microprocessor-based systems needing multi-rail monitoring, deterministic reset timing, and fail-safe software supervision - targeting space-constrained, high-reliability embedded platforms.

FAQ

What is the exact VCC1 reset threshold voltage for MAX6731UTRD3+T?

The MAX6731UTRD3+T has a factory-set VCC1 reset threshold of +3.075V nominal (TZ suffix), with guaranteed range of +3.000V to +3.150V over temperature and supply variations. This value is laser-trimmed during production and does not require external calibration. The threshold exhibits 20ppm/°C tempco and 0.5% hysteresis relative to typical value, ensuring stable trip points across operating conditions. MAX6731UTRD3+T maintains this specification across its full -40°C to +85°C range.

Does MAX6731UTRD3+T support manual reset, and how is it implemented?

Yes, MAX6731UTRD3+T includes an active-low manual reset input (MR) on Pin 4. It features an internal 50kΩ pull-up resistor to VCC1, allowing MR to be left floating or tied directly to VCC1 when unused. A logic-low pulse ≥1µs asserts RST and clears the watchdog timer. MR accepts TTL/CMOS levels (VIL ≤ 0.3×VCC1, VIH ≥ 0.7×VCC1) and rejects glitches <100ns. For noise immunity in long-cable applications, a 0.1µF capacitor from MR to GND is recommended. MAX6731UTRD3+T uses this MR function to enable field-service resets and test-mode initialization.

What are the watchdog timeout periods for MAX6731UTRD3+T?

MAX6731UTRD3+T implements 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. The watchdog clears on any rising or falling edge at WDI (Pin 5); failure to provide such an edge within 1.12s causes WDO to assert low. Leaving WDI unconnected does not disable the watchdog - it will timeout after the initial 35s period. This architecture ensures safe boot completion before supervision begins, then rapid lockup detection during runtime. MAX6731UTRD3+T guarantees these timeouts across temperature and supply voltage.

Is MAX6731UTRD3+T compatible with bidirectional microprocessor reset pins?

Yes, but with caution: MAX6731UTRD3+T's push-pull RST output can cause logic contention when directly connected to a bidirectional µP reset I/O port. To prevent this, insert a 10kΩ series resistor between RST (Pin 1) and the µP reset pin. This limits current during potential bus conflicts while preserving signal integrity and timing margins. The resistor value is noncritical but must be large enough to avoid loading the RST driver yet small enough to maintain fast edge rates. MAX6731UTRD3+T's push-pull design otherwise eliminates external pull-ups required by open-drain alternatives like MAX6730UTRD3+T.

What package and environmental ratings does MAX6731UTRD3+T have?

MAX6731UTRD3+T is supplied in a RoHS-compliant, lead(Pb)-free SOT23-6 package (package code U6+1), measuring 1.6mm × 2.9mm with 0.95mm height. It is fully specified over -40°C to +85°C ambient temperature, with junction temperature rated to +150°C. Absolute maximum ratings include VCC1/VCC2 = -0.3V to +6V, and continuous power dissipation of 347.8mW at +70°C (derating 4.3mW/°C above). The device meets JEDEC moisture sensitivity level MSL-1 and is qualified for industrial applications. MAX6731UTRD3+T carries the "+T" suffix indicating tape-and-reel packaging and lead-free finish.