Analog Devices Inc./Maxim Integrated MAX6728KAVHD3+T

Overview

MAX6728KAVHD3+T from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and PFI (626.5mV internal reference) with 210ms reset timeout, push-pull RST and open-drain PFO outputs, and guaranteed reset validity down to VCC1 or VCC2 = 0.8V - used in telecom power sequencing and industrial multivoltage systems.

For engineers reviewing the MAX6728KAVHD3+T datasheet, MAX6728KAVHD3+T pinout, MAX6728KAVHD3+T application, or MAX6728KAVHD3+T equivalent, this page delivers verified electrical parameters, exact pin functions, dual-supply reset coordination logic, power-fail comparator timing, and validated alternative options for multivoltage system supervision.

Technical Context

The MAX6728KAVHD3+T implements independent dual-threshold voltage monitoring (VCC1 at 4.625V, VCC2 at 3.075V) plus a dedicated power-fail input (PFI) referenced to a 626.5mV internal bandgap, with separate reset assertion logic per monitored rail and a fixed 210ms minimum reset timeout period after all thresholds are reasserted.

It integrates a push-pull active-low RST output referenced to VCC1 and an open-drain active-low PFO output referenced to VCC1, both asserted independently upon threshold violation, with PFO deasserting immediately (no timeout) while RST remains asserted for the full 210ms period - enabling coordinated power-good signaling and hard reset control.

Key Specifications

Pinout & Package

MAX6728KAVHD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 0.95mm profile), compatible with standard SMT reflow profiles and offering thermal performance suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6728KAVHD3+T, MAX6729KAHVD3+T offers push-pull PFO for direct logic interfacing but forfeits interrupt bus compatibility, while TPS3808G33DBVR reduces cost and current draw but eliminates the integrated power-fail monitoring essential for three-rail systems.

Availability

MAX6728KAVHD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6728KAVHD3+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 demanding industrial, automotive, and communications applications, with expertise in power management and system-level supervision.

The MAX6715–MAX6729 family was engineered specifically for multivoltage embedded systems needing simultaneous, independent monitoring of primary, secondary, and auxiliary power rails - with emphasis on low-voltage operation, minimal board space, and robust noise immunity.

FAQ

What is the exact reset threshold voltage for VCC1 on the MAX6728KAVHD3+T?

The MAX6728KAVHD3+T has a factory-trimmed VCC1 reset threshold of 4.625V, with a guaranteed tolerance of ±125mV over temperature and supply variations. This value is encoded in the "KH" suffix per Maxim's Reset Voltage Threshold Suffix Guide and is measured under standard conditions (TA = +25°C, VCC1 ramped at 100mV/s). The MAX6728KAVHD3+T uses this threshold to assert RST when the primary supply falls below specification - critical for 5V system integrity.

Does the MAX6728KAVHD3+T support monitoring a third voltage beyond VCC1 and VCC2?

Yes, the MAX6728KAVHD3+T supports third-voltage monitoring via its dedicated PFI (power-fail input) pin, which compares an external voltage against a precise 626.5mV internal reference. Using a resistor divider network connected to PFI, designers can configure trip points for battery backup rails, DC-DC pre-regulators, or isolated supplies. Unlike RSTIN-based variants, the MAX6728KAVHD3+T uses PFI exclusively for this function - confirmed in the Selector Guide and Electrical Characteristics table.

What is the function of Pin 8 (NC) on the MAX6728KAVHD3+T?

Pin 8 on the MAX6728KAVHD3+T is designated NC (No Connect) and is not internally bonded or electrically functional. It must be left unconnected per the official datasheet Pin Description table and Functional Diagram. This pin exists solely for mechanical symmetry in the SOT23-8 package and carries no signal, power, or reference function - connecting it to any net may cause unintended behavior or violate Maxim's layout recommendations.

How does the PFO output behave relative to the RST output during a power-fail event?

During a power-fail event, the PFO output of the MAX6728KAVHD3+T asserts low immediately when the PFI input falls below 626.5mV, with no timeout delay (typical propagation delay = 2µs). In contrast, the RST output asserts low simultaneously but remains asserted for the full 210ms reset timeout period - even after PFI recovers. This decoupled timing allows the µP to execute emergency shutdown routines triggered by PFO before RST forces a hard reset, a key design feature documented in the Detailed Description section.

Is the MAX6728KAVHD3+T compatible with 1.8V VCC2 operation?

Yes, the MAX6728KAVHD3+T fully supports VCC2 operation down to 0.9V, including 1.8V nominal supplies. Its VCC2 reset threshold is factory-set to 3.075V, making it suitable for monitoring 3.3V I/O rails, while the internal circuitry remains functional and guarantees valid reset output as long as VCC2 ≥ 0.8V - explicitly confirmed in the Absolute Maximum Ratings and Detailed Description sections of the datasheet.