Analog Devices Inc./Maxim Integrated MAX6721AUTWGD3+

Overview

MAX6721AUTWGD3+ from Maxim Integrated is a dual-supply ultra-low-voltage microprocessor supervisory circuit in SOT23-6 package, monitoring VCC1 (primary) and VCC2 (secondary) supplies with factory-trimmed reset thresholds - 4.625V (±125mV) for VCC1 and 3.075V (±75mV) for VCC2 - and featuring watchdog timer (35s startup / 1.12s normal timeout), manual-reset input, and push-pull active-low RST output. It ensures reliable system reset in telecom power management and industrial embedded controllers where supply integrity below 1.8V must be maintained.

For engineers reviewing the MAX6721AUTWGD3+ datasheet, MAX6721AUTWGD3+ pinout, MAX6721AUTWGD3+ application, or MAX6721AUTWGD3+ equivalent, key selection criteria include its guaranteed reset validity down to VCC1/VCC2 = 0.8V, 14µA typical supply current at 3.6V, 140ms minimum reset timeout (D3 suffix), and AEC-Q100-compatibility context for automotive-adjacent industrial use.

Technical Context

The MAX6721AUTWGD3+ integrates dual independent voltage comparators with internal 20ppm/°C tempco references and 0.5% hysteresis, enabling precise brownout detection across -40°C to +125°C. Its watchdog timer operates in dual-mode: a 35s min startup period after reset allows full system initialization before entering 1.12s min normal timeout mode for rapid fault response.

Reset assertion is triggered by any of four conditions: VCC1 falling below 4.625V, VCC2 falling below 3.075V, MR pulled low, or WDI timeout - all forcing RST low for ≥140ms. The push-pull RST output is referenced to VCC1 and sinks up to 3.2mA at 4.5V while maintaining VOL ≤ 0.4V.

Key Specifications

Pinout & Package

SOT23-6 package (package code U6+1), 1.6mm × 2.9mm footprint, 0.95mm height, thermal resistance θJA = 115°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply supervisory applications.

Compared with MAX6721AUTWGD3+, MAX6722AUTWGD3+ offers identical timing and thresholds but requires external pullup, while TPS3808G33DBVR reduces cost and current draw at the expense of dual-supply monitoring and watchdog functionality - making MAX6721AUTWGD3+ optimal for complex multi-rail systems needing robust fault coverage.

Availability

MAX6721AUTWGD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and automotive ADAS ECUs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6721AUTWGD3+ 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 demanding industrial, automotive, and communications applications, with emphasis on reliability, low power, and high integration.

The MAX6715A–MAX6729A family delivers compact, ultra-low-voltage supervisory solutions targeting space-constrained embedded systems where dual-rail monitoring, watchdog safety, and guaranteed operation down to 0.8V are mandatory.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6721AUTWGD3+?

The MAX6721AUTWGD3+ has a factory-trimmed VCC1 reset threshold of 4.625V (typical), with ±125mV tolerance over temperature and supply variations. This value corresponds to the 'W' suffix in the ordering code and is guaranteed across the full -40°C to +125°C operating range per the datasheet's Electrical Characteristics table.

Does the MAX6721AUTWGD3+ support monitoring a third voltage rail?

No, the MAX6721AUTWGD3+ is a dual-supply supervisor and does not include the RSTIN input required for adjustable third-rail monitoring. That feature is present only on variants like MAX6723A–MAX6727A. The MAX6721AUTWGD3+ monitors only VCC1 and VCC2 with fixed thresholds.

What is the function of the WDI pin on the MAX6721AUTWGD3+?

The WDI (Watchdog Input) pin on the MAX6721AUTWGD3+ monitors microprocessor activity: a rising or falling edge clears the internal watchdog timer. If WDI remains static longer than 1.12s (normal mode) or 35s (startup mode), RST asserts for 140ms. Leaving WDI unconnected disables the watchdog using an internal 200nA detector.

Can the MAX6721AUTWGD3+ operate with VCC1 = 1.2V?

Yes, the MAX6721AUTWGD3+ is guaranteed to function correctly with VCC1 as low as 0.8V, including valid reset assertion and RST output logic levels. At VCC1 = 1.2V, the push-pull RST output maintains VOL ≤ 0.3V when sinking 100µA, satisfying most low-voltage µP reset input requirements.

Is the MAX6721AUTWGD3+ pin-compatible with other devices in the MAX67xx family?

The MAX6721AUTWGD3+ uses the SOT23-6 package and shares pinout compatibility with MAX6722A, MAX6725A, and MAX6726A variants. However, output type (push-pull vs. open-drain), reset thresholds, and feature enablement (e.g., PFI/PFO) differ - verify electrical and functional match before substitution.