Analog Devices Inc./Maxim Integrated MAX6729KATED3+

Overview

MAX6729KATED3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and RSTIN (auxiliary) supply rails with factory-trimmed thresholds of 4.625V (VTH1), 3.075V (VTH2), and 626.5mV (RSTIN reference). It provides push-pull active-low reset output (RST), manual reset input (MR), watchdog timer (35s startup / 1.12s normal timeout), and power-fail input/output (PFI/PFO) - all operating over –40°C to +85°C for telecom and industrial embedded systems.

For engineers reviewing the MAX6729KATED3+ datasheet, MAX6729KATED3+ pinout, MAX6729KATED3+ application, or MAX6729KATED3+ equivalent, key selection criteria include its triple-supply monitoring capability, guaranteed reset validity down to VCC1/VCC2 = 0.8V, 14µA typical supply current at 3.6V, 210ms (min) reset timeout, and integrated PFO with push-pull drive referenced to VCC1.

Technical Context

The MAX6729KATED3+ implements dual independent voltage comparators for VCC1 and VCC2, plus a dedicated high-impedance RSTIN comparator with 626.5mV internal reference, enabling precise monitoring of a third rail down to 0.62V via external resistor divider. Its reset logic asserts RST low if any monitored voltage falls below threshold, and holds reset for a minimum 210ms after all supplies recover.

This device integrates a dual-mode watchdog timer: a 35s (min) initial timeout after power-up/manual reset to accommodate system boot, followed by a 1.12s (min) normal timeout requiring periodic WDI transitions; it also includes a power-fail comparator with 2µs propagation delay from PFI to PFO and 3mV hysteresis.

Key Specifications

Pinout & Package

MAX6729KATED3+ is housed in an 8-pin SOT23-8 package (3.0mm × 1.6mm × 1.1mm), optimized for space-constrained PCB layouts while supporting thermal dissipation up to +85°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6728KAED3+, MAX6729KATED3+ eliminates the need for an external PFO pullup resistor; compared with TPS3808G33DBVR, it adds RSTIN-based third-rail monitoring and integrated push-pull PFO - making it uniquely suited for complex multivoltage systems requiring coordinated reset and early power-fail warning.

Availability

MAX6729KATED3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, network routers, and battery-powered edge gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6729KATED3+ 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 power, sensing, and connectivity applications, with deep expertise in supervisory and power-management solutions.

The MAX6715–MAX6729 family was engineered specifically for multivoltage embedded systems needing compact, ultra-low-power supervision of primary, secondary, and auxiliary rails - targeting telecom, industrial, and computing equipment where reliability and footprint matter.

FAQ

What is the exact reset timeout period for MAX6729KATED3+?

The MAX6729KATED3+ has a minimum reset timeout period of 210ms, as indicated by the "D3" suffix in its part number per Maxim's Reset Timeout Period Suffix Guide. This value is guaranteed over the full –40°C to +85°C operating temperature range and ensures sufficient hold time for microprocessor initialization and peripheral stabilization before release.

Does MAX6729KATED3+ support monitoring a third voltage rail, and how is it configured?

Yes, MAX6729KATED3+ supports third-rail monitoring via its RSTIN pin, which compares the applied voltage against a precise 626.5mV internal reference. To monitor a custom voltage (e.g., 1.2V or 1.8V), connect an external resistor divider between the rail and GND, with the midpoint fed to RSTIN - the threshold is set by V_{EXT_TH} = 626.5mV × (R1 + R2)/R2.

What is the function of the PFO pin on MAX6729KATED3+, and how does it differ from RST?

The PFO (Power-Fail Output) pin on MAX6729KATED3+ is an active-low push-pull output that asserts independently when the PFI input falls below 626.5mV - signaling impending supply failure *before* a full reset is triggered. Unlike RST, PFO deasserts immediately upon recovery (no timeout), enabling early warning interrupts or controlled software shutdown without halting the entire system.

Can MAX6729KATED3+ operate reliably during brownout conditions where VCC1 drops below 1.8V?

Yes, MAX6729KATED3+ guarantees valid reset output logic state as long as either VCC1 or VCC2 remains above 0.8V - confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. This allows robust operation during deep brownouts where traditional supervisors would fail, provided at least one supply stays within specification.

What watchdog timeout modes does MAX6729KATED3+ support, and how are they triggered?

MAX6729KATED3+ features a dual-mode watchdog: a 35s (min) startup timeout after power-on or manual reset, followed by a 1.12s (min) normal timeout once the first valid WDI edge occurs. The transition occurs automatically - no software configuration is needed - ensuring safe boot windows while maintaining tight runtime fault detection.