Analog Devices Inc./Maxim Integrated MAX6729KAZGD3+

Overview

MAX6729KAZGD3+ 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) with push-pull active-low reset output, power-fail input/output, and watchdog timer. It guarantees valid reset assertion down to VCC1 or VCC2 = 0.8V and supports industrial temperature range (–40°C to +85°C). Used in multivoltage telecom and embedded systems requiring reliable brownout detection and orderly shutdown.

For engineers reviewing the MAX6729KAZGD3+ datasheet, MAX6729KAZGD3+ pinout, MAX6729KAZGD3+ application, or MAX6729KAZGD3+ equivalent, key selection criteria include its triple-supply monitoring capability, 210ms (min) reset timeout, push-pull RST/PFO outputs referenced to VCC1, integrated power-fail comparator with 2µs delay, and guaranteed operation at ultra-low supply voltages.

Technical Context

The MAX6729KAZGD3+ implements a dual-threshold voltage monitor for primary (VCC1) and secondary (VCC2) supplies plus a high-impedance RSTIN input with 626.5mV internal reference, enabling precise third-voltage supervision via external resistor divider. Its power-fail comparator (PFI/PFO) operates independently with 3mV hysteresis and 2µs propagation delay.

This device integrates a dual-mode watchdog timer: 35s (min) startup period after reset, followed by 1.12s (min) normal timeout triggered by WDI edge transitions. Reset logic remains valid while either VCC1 or VCC2 ≥ 0.8V, and all outputs are fully specified across –40°C to +85°C.

Key Specifications

Pinout & Package

MAX6729KAZGD3+ is housed in an 8-pin SOT23 package (3.0mm × 1.6mm × 1.1mm height), optimized for space-constrained PCB layouts in portable and networking equipment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6729KAZGD3+, MAX6728KAZGD3+ offers identical supervision capability but requires external biasing for PFO, while TPS3808G33DBVR reduces feature set and package size at the expense of triple-voltage flexibility and power-fail alerting - making MAX6729KAZGD3+ optimal for complex multirail systems demanding full fault coverage.

Availability

MAX6729KAZGD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial control systems, and battery-powered IoT gateways requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6729KAZGD3+ 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 design leader specializing in precision analog, power management, and interface solutions for industrial, automotive, and communications markets.

The MAX6715–MAX6729 family was engineered specifically for multivoltage embedded systems requiring simultaneous monitoring of primary, secondary, and auxiliary rails - with emphasis on ultra-low quiescent current, guaranteed reset validity at sub-1V supplies, and integrated watchdog/power-fail functions.

FAQ

What is the exact reset timeout period for MAX6729KAZGD3+?

The MAX6729KAZGD3+ has a minimum reset timeout period of 210ms, as indicated by the "D3" suffix in its part number. This value is guaranteed over the full –40°C to +85°C operating temperature range and ensures sufficient reset assertion time for processor initialization, memory self-test, and peripheral configuration before release.

Does MAX6729KAZGD3+ support monitoring a 1.2V core supply?

Yes, MAX6729KAZGD3+ supports monitoring a 1.2V core supply via its RSTIN input using an external resistor divider. With a 626.5mV internal reference, a standard divider (e.g., R1 = 100kΩ, R2 = 100kΩ) sets the trip point at 1.253V - well within the ±1.5% typical accuracy of the RSTIN comparator and compatible with 1.2V ±5% supply tolerances.

How does the power-fail function work on MAX6729KAZGD3+?

The MAX6729KAZGD3+ uses its PFI input to monitor an external voltage divider; when PFI falls below 626.5mV, the PFO output asserts low immediately (2µs typical delay) without reset timeout. This enables real-time power-fail interrupts to firmware or fast-acting shutdown circuits - distinct from the reset function, which requires sustained undervoltage for the full timeout period.

Can MAX6729KAZGD3+ operate with VCC1 = 2.5V and VCC2 = 1.8V?

Yes, MAX6729KAZGD3+ is fully specified for VCC1 from 1.8V to 5.0V and VCC2 from 0.9V to 3.3V. At VCC1 = 2.5V and VCC2 = 1.8V, all functions - including RST push-pull drive strength, MR input thresholds, and watchdog timing - remain within datasheet limits, and reset validity is guaranteed as long as either supply stays ≥ 0.8V.

What is the watchdog startup behavior of MAX6729KAZGD3+?

After any reset event (power-up, MR assertion, or watchdog timeout), MAX6729KAZGD3+ enters a 35s (minimum) long startup watchdog mode. The 1.12s (minimum) normal timeout begins only after the first valid WDI edge transition occurs before the 35s window expires - preventing false timeouts during boot and ensuring robust runtime supervision.