Analog Devices Inc./Maxim Integrated MAX6729AKAYHD3+T

Overview

MAX6729AKAYHD3+T from Maxim Integrated is a dual-supply ultra-low-voltage microprocessor supervisory circuit with factory-trimmed reset thresholds for VCC1 (4.625V typ) and VCC2 (1.313V typ), 140ms minimum reset timeout, push-pull active-low RST output, power-fail input/output (PFI/PFO), and watchdog timer disable capability. It ensures reliable system reset in multivoltage embedded systems such as telecom power modules and industrial controllers.

For engineers reviewing the MAX6729AKAYHD3+T datasheet, MAX6729AKAYHD3+T pinout, MAX6729AKAYHD3+T application, or MAX6729AKAYHD3+T equivalent, key selection criteria include guaranteed reset validity down to VCC1/VCC2 = 0.8V, 14μA typical supply current at 3.6V, immunity to short VCC transients, and support for triple-voltage monitoring via RSTIN with 626.5mV internal reference.

Technical Context

The MAX6729AKAYHD3+T integrates dual independent voltage monitors (VCC1 and VCC2), a power-fail comparator (PFI → PFO), manual-reset input (MR), and watchdog timer logic - all operating from either supply rail. Its reset assertion is triggered by any monitored voltage falling below its threshold, MR activation, or watchdog timeout, with reset held for a fixed 140ms minimum period after recovery.

It features push-pull RST and PFO outputs referenced to VCC1, open-drain-compatible MR with 50kΩ internal pullup, and WDI unconnected-state detection (200nA current source). The device guarantees correct reset logic state when VCC1 ≥ 0.8V or VCC2 ≥ 0.8V, enabling brownout-safe operation in low-power systems.

Key Specifications

Pinout & Package

MAX6729AKAYHD3+T is housed in an 8-pin SOT23 package (package code K8SN+1), with 0.65mm pitch, JEDEC MO-203AA outline, and land pattern 90-0176. Thermal resistance θJA = 180°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6729AKAYHD3+T, MAX6728AKAYHD3+T removes watchdog capability while retaining identical dual-supply supervision and PFI/PFO features, whereas TPS3808G33DBVR reduces integration depth to single-rail monitoring with lower quiescent current but no auxiliary voltage support.

Availability

MAX6729AKAYHD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and automotive ADAS applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6729AKAYHD3+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, emphasizing reliability, low power, and high integration.

The MAX6715A–MAX6729A family delivers compact, ultra-low-voltage supervisory solutions targeting multirail embedded systems where space, power, and robustness are critical - especially in harsh-environment power management.

FAQ

What is the exact reset timeout period for MAX6729AKAYHD3+T?

The MAX6729AKAYHD3+T has a guaranteed minimum reset timeout period of 140ms (D3 suffix), with typical value 210ms and maximum 280ms across temperature and voltage. This fixed timeout ensures sufficient hold time for microprocessor initialization and peripheral configuration before release, and is factory-trimmed for accuracy without external components.

Does MAX6729AKAYHD3+T support monitoring a third voltage supply?

Yes, MAX6729AKAYHD3+T supports third-voltage monitoring via the RSTIN pin, which uses a precise 626.5mV internal reference. By connecting an external resistor divider from the target supply to RSTIN and GND, users can set custom thresholds from 0.62V up to 5.5V - enabling supervision of auxiliary rails like battery voltage or isolated bias supplies.

What is the function of the PFI and PFO pins on MAX6729AKAYHD3+T?

On MAX6729AKAYHD3+T, PFI is a high-impedance input that triggers the power-fail comparator when voltage falls below 626.5mV; PFO is its corresponding active-low push-pull output that asserts within 2µs. This pair enables early warning of supply degradation - for example, signaling a microcontroller to save state before main rail collapse - without resetting the system.

Can MAX6729AKAYHD3+T operate reliably during severe supply brownout conditions?

Yes, MAX6729AKAYHD3+T guarantees correct reset output logic state as long as either VCC1 ≥ 0.8V or VCC2 ≥ 0.8V - a critical feature for automotive and industrial applications experiencing cranking dips or partial rail failure. Its internal architecture maintains supervision integrity far below typical 1.8V logic thresholds.

Is the watchdog timer on MAX6729AKAYHD3+T enabled by default?

No, the watchdog timer on MAX6729AKAYHD3+T is disabled by default when the WDI pin is left unconnected. An internal 200nA current source detects this condition and disables watchdog functionality. To enable it, WDI must be actively driven with rising/falling edges - and the first valid transition initiates the 35s startup timeout before entering 1.12s normal mode.