Analog Devices Inc./Maxim Integrated MAX6720UTSHD3+T

Overview

MAX6720UTSHD3+T from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in SOT23-6 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and an externally adjustable RSTIN input (626.5mV reference). It asserts active-low push-pull reset for ≥210ms after any supply drop, supports manual reset and watchdog timer, and operates from -40°C to +85°C. Used in telecom power management and multivoltage embedded systems.

For engineers reviewing the MAX6720UTSHD3+T datasheet, MAX6720UTSHD3+T pinout, MAX6720UTSHD3+T application, or MAX6720UTSHD3+T equivalent, key selection factors include confirmed triple-supply monitoring capability, 210ms reset timeout, push-pull RST output referenced to VCC1, guaranteed reset validity down to VCC1/VCC2 = 0.8V, and low 14µA typical supply current at 3.6V.

Technical Context

The MAX6720UTSHD3+T integrates dual factory-trimmed voltage comparators (VTH1 = 4.625V, VTH2 = 3.075V) and a precision 626.5mV internal reference for RSTIN-based third-supply monitoring. Its reset logic remains valid while either VCC1 or VCC2 ≥ 0.8V, enabling reliable brownout detection in low-voltage systems.

It features a dual-mode watchdog timer with 35s minimum startup period and 1.12s minimum normal timeout, triggered by WDI edge transitions. The push-pull RST output is referenced to VCC1 and sinks up to 3.2mA at 4.5V, while MR includes a 50kΩ internal pullup to VCC1.

Key Specifications

Pinout & Package

MAX6720UTSHD3+T uses a 6-pin SOT23-6 package with gull-wing leads, 1.27mm pitch, and 2.9mm × 1.6mm footprint. Pin 1 is marked with a dot; device orientation follows JEDEC MO-178 standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supervisory circuit applications.

Compared with MAX6720UTSHD3+T, the MAX6720UTSHD5+T offers extended reset timing without layout change, while TPS3808G33DBVR reduces functionality and drive capability-making it suitable only for minimal single-rail applications where triple monitoring is unnecessary.

Availability

MAX6720UTSHD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial control, and portable medical devices requiring stable component supply, precise triple-voltage supervision, and guaranteed -40°C to +85°C operation.

Supply support for MAX6720UTSHD3+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, mixed-signal, and power-management ICs for industrial, automotive, and communications markets.

The MAX6715–MAX6729 family delivers ultra-low-voltage supervisory circuits optimized for multirail systems requiring simultaneous monitoring of primary, secondary, and auxiliary supplies with minimal board space and power consumption.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6720UTSHD3+T?

The MAX6720UTSHD3+T has a factory-trimmed VCC1 reset threshold of 4.625V (±125mV), corresponding to the 'SH' suffix per Maxim's Reset Voltage Threshold Suffix Guide. This value is measured at the VCC1 pin and remains stable across temperature due to 20ppm/°C tempco. The MAX6720UTSHD3+T uses this threshold to assert reset when the primary supply falls below specification, ensuring compatibility with 5V nominal systems.

Does the MAX6720UTSHD3+T support monitoring a third voltage, and how is it configured?

Yes, the MAX6720UTSHD3+T supports third-voltage monitoring via its RSTIN pin, which compares the applied voltage against a precise 626.5mV internal reference. To configure, connect an external resistor divider from the target supply to GND, with the midpoint fed to RSTIN. The monitored threshold is calculated as V_{EXT_TH} = 626.5mV × (R1 + R2)/R2. The MAX6720UTSHD3+T guarantees RSTIN input current ≤±25nA, enabling high-resistance dividers that minimize system power loss.

What type of reset output does the MAX6720UTSHD3+T provide, and what are its drive capabilities?

The MAX6720UTSHD3+T provides an active-low push-pull reset output (RST pin) referenced to VCC1. It sources up to 800µA at VCC1 ≥ 4.5V and sinks up to 3.2mA at VCC1 ≥ 4.5V, eliminating the need for an external pullup resistor. This direct-drive capability ensures robust interfacing with microprocessor reset inputs, including those with bidirectional pins when used with a 4.7kΩ series resistor. The MAX6720UTSHD3+T's push-pull architecture improves noise immunity versus open-drain alternatives.

How does the watchdog timer function on the MAX6720UTSHD3+T, and what are its timing modes?

The MAX6720UTSHD3+T implements a dual-mode watchdog timer: a 35s minimum startup period after any reset event (power-up, MR, or watchdog timeout), followed by a 1.12s minimum normal timeout once the first valid WDI edge is detected. The timer clears on any rising or falling edge at WDI and triggers reset if no transition occurs within the active timeout window. This architecture accommodates lengthy boot sequences while maintaining tight fault-response timing during runtime-key for reliable operation of the MAX6720UTSHD3+T in safety-critical systems.

Is the MAX6720UTSHD3+T compatible with systems where VCC1 or VCC2 drops below 1.0V during brownout conditions?

Yes, the MAX6720UTSHD3+T guarantees correct reset output logic state even when VCC1 or VCC2 falls to 0.8V, per its Absolute Maximum Ratings and Electrical Characteristics tables. This capability enables early brownout detection in ultra-low-voltage systems where other supervisors fail. The MAX6720UTSHD3+T maintains valid reset assertion down to this level, ensuring deterministic behavior during gradual supply collapse-critical for data integrity in battery-powered or energy-harvesting applications.