Analog Devices Inc./Maxim Integrated MAX6721UTSYD3+T

Overview

MAX6721UTSYD3+T from Maxim Integrated is a dual-voltage microprocessor supervisory circuit in 6-pin SOT23-6 package, monitoring VCC1 (4.625V threshold) and VCC2 (3.075V threshold) with 210ms reset timeout, watchdog timer, manual reset input, and open-drain active-low RST output - used to ensure reliable power-on reset and brownout recovery in multivoltage embedded systems.

For engineers reviewing the MAX6721UTSYD3+T datasheet, MAX6721UTSYD3+T pinout, MAX6721UTSYD3+T application, or MAX6721UTSYD3+T equivalent, key selection factors include guaranteed reset validity down to VCC = 0.8V, 14µA typical supply current at 3.6V, immunity to short VCC transients, and compatibility with manual reset, watchdog, and dual-supply monitoring requirements in space-constrained industrial and telecom designs.

Technical Context

The MAX6721UTSYD3+T integrates two independent voltage comparators for primary (VCC1) and secondary (VCC2) supplies, each with factory-trimmed thresholds (4.625V and 3.075V), a 210ms minimum reset timeout timer, and a dual-mode watchdog (35s startup / 1.12s normal mode). It asserts an open-drain active-low RST when either supply drops below its threshold or MR is pulled low.

It features a dedicated WDI input with edge-triggered watchdog clearing, internal 50kΩ MR pullup, and guaranteed reset assertion validity even when VCC1 or VCC2 falls as low as 0.8V - enabling robust operation during deep brownouts without external support circuitry.

Key Specifications

Pinout & Package

MAX6721UTSYD3+T is housed in a 6-pin SOT23-6 package (2.9mm × 1.6mm × 1.1mm), optimized for high-density PCB layouts. Pin functions are validated per Maxim's official pin description table for MAX6721 series.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6722UTSYD3+T, the MAX6721UTSYD3+T offers open-drain flexibility for mixed-voltage µP interfaces but requires a pullup; versus TPS3808G33DBVR, it delivers full dual-supply supervision and watchdog at higher IQ, making it essential for complex multirail systems demanding coordinated reset behavior.

Availability

MAX6721UTSYD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, portable medical devices, and network switch designs requiring stable component supply, long-term lifecycle support, and guaranteed lead-free packaging.

Supply support for MAX6721UTSYD3+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) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The MAX6715–MAX6729 family was designed specifically for space-constrained multivoltage systems needing reliable, low-power, dual- or triple-supply supervision with integrated watchdog and manual reset - targeting telecom, industrial control, and portable electronics.

FAQ

What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6721UTSYD3+T?

The MAX6721UTSYD3+T has factory-trimmed reset thresholds of 4.625V for VCC1 (primary supply) and 3.075V for VCC2 (secondary supply), as indicated by the "SY" suffix per Maxim's Reset Voltage Threshold Suffix Guide. These values are specified over -40°C to +85°C with ±1.5% tolerance and include built-in hysteresis to prevent chatter near trip points.

Does the MAX6721UTSYD3+T support watchdog functionality, and how is it configured?

Yes, the MAX6721UTSYD3+T includes a dual-mode watchdog timer with a 35s minimum startup period (after power-up or reset) and a 1.12s minimum normal-mode timeout. It is configured via the WDI pin: any rising or falling edge clears the timer. No external components or configuration registers are required - operation is fully hardware-based and deterministic.

What package type and pin count does the MAX6721UTSYD3+T use?

The MAX6721UTSYD3+T uses a 6-pin SOT23-6 package (2.9mm × 1.6mm × 1.1mm body size) with gull-wing leads. This compact, surface-mount package supports automated assembly and meets JEDEC MO-178 standards. The "UT" prefix in the part number explicitly denotes the SOT23-6 variant per Maxim's Ordering Information table.

Is the reset output of the MAX6721UTSYD3+T push-pull or open-drain?

The MAX6721UTSYD3+T features an open-drain active-low RST output (Pin 1), requiring an external pullup resistor to VCC1 or another appropriate rail. This configuration allows level-shifting and direct interfacing with bidirectional µP reset pins - unlike push-pull variants (e.g., MAX6722), which drive high actively and cannot be wire-OR'd.

What is the minimum supply voltage at which the MAX6721UTSYD3+T guarantees valid reset assertion?

The MAX6721UTSYD3+T guarantees correct reset output logic state down to VCC1 or VCC2 = 0.8V, as confirmed in the Absolute Maximum Ratings and Detailed Description sections. This ensures reliable brownout detection even during severe voltage sags where many supervisors fail - no external support circuitry is needed to maintain reset validity.