Analog Devices Inc./Maxim Integrated MAX6721UTZWD3+T

Overview

MAX6721UTZWD3+T from Maxim Integrated is a dual-voltage microprocessor supervisory IC monitoring VCC1 (primary) and VCC2 (secondary) supplies, with watchdog timer, manual reset input, and open-drain active-low RST output. It asserts reset when VCC1 drops below 3.075V (typ), VCC2 falls below 2.188V (typ), or WDI timeout occurs, maintaining reset for 210ms (min). Used in telecom power management and industrial embedded systems requiring reliable brownout detection.

For engineers reviewing the MAX6721UTZWD3+T datasheet, MAX6721UTZWD3+T pinout, MAX6721UTZWD3+T application, or MAX6721UTZWD3+T equivalent, key selection criteria include dual-supply threshold accuracy (±1.5% over temp), guaranteed reset validity down to VCC = 0.8V, 14µA typical supply current at 3.6V, and integrated 35s startup / 1.12s normal watchdog timing.

Technical Context

The MAX6721UTZWD3+T implements a dual-threshold comparator architecture with independent VCC1 and VCC2 monitoring paths, each referencing factory-trimmed bandgap references. Its reset logic combines asynchronous voltage fault detection with a digital timeout counter that restarts on any threshold violation before timeout completion.

It integrates a dual-mode watchdog timer: a 35s minimum initial period after reset for system boot, followed by a 1.12s minimum normal timeout triggered by the first WDI edge; WDI accepts CMOS/TTL-compatible inputs with 100ns glitch rejection and 200ns MR-to-reset delay.

Key Specifications

Pinout & Package

MAX6721UTZWD3+T is housed in a 6-pin SOT23-6 package (2.9mm × 1.6mm × 1.1mm), RoHS-compliant and lead-free (+T suffix), with thermal pad omitted. Pin 1 is marked via dot; device orientation follows JEDEC MO-178.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6721UTZWD3+T, TPS3808G33DBVR reduces BOM count in single-rail systems but forfeits dual-monitoring capability, while ADM6712S30ARJZ-R7 saves board area yet necessitates discrete components to replicate VCC2 supervision and watchdog functions-making MAX6721UTZWD3+T optimal for integrated dual-rail reliability.

Availability

MAX6721UTZWD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and medical imaging equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6721UTZWD3+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 power management and reliability.

The MAX6715–MAX6729 family delivers ultra-low-voltage supervisory circuits optimized for multirail embedded systems where simultaneous monitoring of primary and secondary supplies is essential for safe boot and fault recovery.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6721UTZWD3+T?

The MAX6721UTZWD3+T has a VCC1 reset threshold of 3.000V (min) to 3.150V (max), with 3.075V typical, and a VCC2 threshold of 2.125V (min) to 2.250V (max), with 2.188V typical. These values are factory-trimmed and specified across -40°C to +85°C per the ZW suffix in the part number, which maps to VTH1 = 3.075V and VTH2 = 2.188V in Maxim's Reset Voltage Threshold Suffix Guide.

Does the MAX6721UTZWD3+T support watchdog functionality, and how is it configured?

Yes, the MAX6721UTZWD3+T includes a dual-mode watchdog timer with a 35s minimum startup period and 1.12s minimum normal timeout. It is enabled by default and requires no external configuration-WDI pin transitions (rising or falling edges) reset the timer. The first valid WDI edge after reset initiates the 1.12s normal mode; absence of edges for >1.12s asserts RST for 210ms.

What package type and pin count does the MAX6721UTZWD3+T use?

The MAX6721UTZWD3+T uses a 6-pin SOT23-6 package (JEDEC MO-178), measuring 2.9mm × 1.6mm × 1.1mm, with lead-free (+T) finish. Pin 1 is marked by a dot; the device is not pin-compatible with 5-pin or 8-pin variants in the MAX6715–MAX6729 family due to differing pin assignments and feature sets.

Can the MAX6721UTZWD3+T monitor three supply voltages?

No, the MAX6721UTZWD3+T is a dual-voltage supervisor monitoring only VCC1 and VCC2. It does not include RSTIN or PFI inputs-those features are present only in MAX6723–MAX6729 variants. For triple-voltage monitoring, consider MAX6723UTZWD3+T (RSTIN-enabled) or MAX6728KAZWD3+T (PFI/PFO-enabled), both in the same family.

What is the reset output type and drive capability of the MAX6721UTZWD3+T?

The MAX6721UTZWD3+T provides an open-drain active-low RST output (Pin 1) capable of sinking ≥1.2mA at VCC ≥ 2.7V (VOL ≤ 0.3V). It requires an external pullup resistor-typically 10kΩ to VCC1-and is compatible with bidirectional µP reset pins. It does not offer push-pull or active-high reset outputs; those are available in MAX6722/MAX6729 variants.