Analog Devices Inc./Maxim Integrated MAX6726KAYDD3+

Overview

MAX6726KAYDD3+ 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 an externally adjustable RSTIN input (626.5mV reference). It provides push-pull active-high RST and active-low RST outputs, manual reset input, watchdog timer with 35s startup/1.12s normal timeout, and guaranteed reset validity down to VCC1 or VCC2 = 0.8V - used in multivoltage telecom power systems for reliable brownout detection and orderly processor recovery.

For engineers reviewing the MAX6726KAYDD3+ datasheet, MAX6726KAYDD3+ pinout, MAX6726KAYDD3+ application, or MAX6726KAYDD3+ equivalent, key selection factors include its dual-reset-output architecture (RST high/low), factory-trimmed dual-threshold precision (±1.5% over temperature), 14µA typical supply current at 3.6V, 210ms minimum reset timeout, and integrated watchdog with long-startup mode for complex boot sequences.

Technical Context

The MAX6726KAYDD3+ implements a dual-comparator architecture with independent voltage sensing paths for VCC1 and VCC2, plus a dedicated high-impedance RSTIN comparator referenced to a 626.5mV internal bandgap. Its reset logic combines OR-ed fault conditions (VCC1/VCC2 undervoltage, RSTIN low, MR low, or WDI timeout) with a monotonic reset timeout timer that restarts on any new fault before timeout completion.

It integrates a dual-mode watchdog: a 35s minimum initial timeout after any reset event enables full system initialization, followed by a 1.12s minimum normal-mode timeout triggered by the first WDI edge; both modes clear on rising/falling WDI transitions. The device uses BiCMOS process (1072 transistors) and guarantees correct reset state down to 0.8V on either supply rail.

Key Specifications

Pinout & Package

MAX6726KAYDD3+ is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.0mm height), RoHS-compliant and lead-free (+ suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725KAUTD3+, MAX6726KAYDD3+ delivers direct-drive reset signaling without external components; versus TPS3808G33DBVR, it provides full triple-supply coverage, programmable auxiliary monitoring, and dual-mode watchdog - making it the only option for safety-critical multivoltage systems requiring guaranteed 0.8V reset validity.

Availability

MAX6726KAYDD3+ is available at Aetrix Electronics and suitable for telecom power sequencing, industrial PLC controllers, server management units, and medical diagnostic imaging systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6726KAYDD3+ 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 high-performance 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 precise, low-power supervision with integrated watchdog and auxiliary monitoring - targeting telecom infrastructure, servers, and portable medical devices.

FAQ

What are the factory-trimmed reset thresholds for MAX6726KAYDD3+?

The MAX6726KAYDD3+ has factory-trimmed VCC1 reset threshold of 4.625V and VCC2 reset threshold of 3.075V, both specified with ±1.5% tolerance over -40°C to +85°C. These values are encoded in the "YA" suffix per Maxim's Reset Voltage Threshold Suffix Guide and are laser-trimmed during production for high accuracy without external calibration.

Does MAX6726KAYDD3+ support both active-high and active-low reset outputs simultaneously?

Yes, MAX6726KAYDD3+ provides concurrent active-high RST (pin 1) and active-low RST (pin 8), both push-pull outputs referenced to VCC1. This eliminates the need for external level-shifting or inversion circuitry when interfacing with microprocessors that require bidirectional reset signaling or multiple reset polarity domains.

What is the function of the PFI and PFO pins on MAX6726KAYDD3+?

On MAX6726KAYDD3+, PFI (pin 7) is a high-impedance input with 626.5mV internal reference used to monitor an auxiliary supply via external resistor divider; PFO (pin 4) is its corresponding active-low push-pull output that asserts immediately when PFI falls below threshold - with no reset timeout - enabling fast power-fail interrupts for orderly shutdown.

How does the watchdog timer in MAX6726KAYDD3+ operate during system boot?

The MAX6726KAYDD3+ watchdog starts in long-mode (35s minimum timeout) after any reset event (power-up, MR, or WDI timeout), allowing full firmware initialization. Upon detecting the first valid WDI edge, it switches to normal-mode (1.12s minimum timeout). This two-phase behavior prevents spurious resets during boot while maintaining tight fault detection in steady-state operation.

What is the minimum operating voltage guarantee for MAX6726KAYDD3+ reset functionality?

MAX6726KAYDD3+ guarantees correct reset output logic state down to VCC1 = 0.8V or VCC2 = 0.8V - meaning the RST and RST outputs remain valid and asserted as long as at least one supply remains ≥0.8V. This ensures reliable brownout detection even during severe undervoltage conditions common in telecom and industrial power systems.