Analog Devices Inc./Maxim Integrated MAX6729AKAVHD3+

Overview

MAX6729AKAVHD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory IC in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and RSTIN (adjustable auxiliary) supply rails. It asserts active-low reset when any monitored voltage falls below its threshold (VTH1 = 4.625 V, VTH2 = 3.075 V, VRSTIN = 626.5 mV), with 280 ms minimum reset timeout, watchdog timer, manual-reset input, and power-fail detection - used in telecom power systems requiring reliable brownout protection.

For engineers reviewing the MAX6729AKAVHD3+ datasheet, MAX6729AKAVHD3+ pinout, MAX6729AKAVHD3+ application, or MAX6729AKAVHD3+ equivalent, key selection criteria include dual/three-rail monitoring capability, guaranteed reset validity down to VCC = 0.8 V, push-pull RST/RST2/PFO outputs, 14 µA typical supply current at 3.6 V, and AEC-Q100-qualified variants for automotive-grade reliability.

Technical Context

The MAX6729AKAVHD3+ implements independent voltage comparators for VCC1 (1.58–4.63 V factory-trimmed thresholds), VCC2 (0.79–3.08 V), and RSTIN (0.62 V internal reference). Its reset logic combines OR-gated fault detection across all three inputs, with a programmable 280 ms minimum timeout (D5 suffix) and dual-mode watchdog (35 s startup / 1.12 s normal mode).

It features push-pull RST, RST2, and PFO outputs referenced to VCC1 and VCC2 respectively, MR input with 50 kΩ internal pullup to VCC1, and WDI with 200 nA unconnected-state detection. All functions operate over –40°C to +125°C with guaranteed functionality down to VCC1 or VCC2 = 0.8 V.

Key Specifications

Pinout & Package

MAX6729AKAVHD3+ uses an 8-pin SOT23 package (JEDEC MO-203AA), with pins arranged in standard SOT23-8 footprint: 1.5 mm × 2.9 mm body, 0.95 mm height, 0.65 mm pitch. Pin 1 marked by beveled corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6725AKAVHD3+, MAX6729AKAVHD3+ offers push-pull outputs eliminating external resistors; versus TPS3808G33DBVR, it delivers triple-supply coverage, adjustable monitoring, and watchdog functionality essential for complex embedded systems.

Availability

MAX6729AKAVHD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, automotive ADAS, and network equipment requiring stable component supply with extended temperature support and AEC-Q100 compliance options.

Supply support for MAX6729AKAVHD3+ 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, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.

The MAX6715A–MAX6729A family delivers ultra-low-voltage, multi-rail supervisory circuits optimized for space-constrained, high-reliability systems requiring guaranteed reset behavior across wide temperature and supply ranges.

FAQ

What is the reset timeout period for MAX6729AKAVHD3+?

The MAX6729AKAVHD3+ has a minimum reset timeout period of 280 ms, indicated by the "D5" suffix in its part number. This timeout begins when all monitored supplies (VCC1, VCC2, RSTIN) rise above their respective thresholds, and ensures the microprocessor remains held in reset long enough to complete stable power-up sequencing. The actual timeout may vary slightly with temperature and supply conditions but remains guaranteed ≥280 ms across –40°C to +125°C.

Does MAX6729AKAVHD3+ support monitoring a third voltage rail?

Yes, MAX6729AKAVHD3+ supports triple-voltage monitoring via its RSTIN pin, which features a precise 626.5 mV internal reference. By connecting an external resistor divider between the third supply and ground, with the midpoint fed to RSTIN, users can configure monitoring thresholds down to 0.62 V. This enables supervision of auxiliary rails such as DDR memory VTT, FPGA configuration supplies, or sensor bias voltages without adding discrete components.

What are the output drive types for RST, RST2, and PFO on MAX6729AKAVHD3+?

MAX6729AKAVHD3+ provides push-pull outputs for RST (referenced to VCC1), RST2 (referenced to VCC2), and PFO (referenced to VCC1). These outputs do not require external pullup resistors and can actively drive high or low. RST and RST2 assert active-low during fault conditions; PFO asserts active-low immediately upon PFI falling below 626.5 mV, with no timeout delay - enabling fast power-fail interrupt signaling.

Can MAX6729AKAVHD3+ operate reliably during deep brownout conditions?

Yes, MAX6729AKAVHD3+ guarantees correct reset output logic states even when VCC1 or VCC2 drops to 0.8 V - significantly lower than most competing supervisors. This ensures deterministic behavior during severe brownouts common in automotive cold-crank or industrial power-dip scenarios. The internal bandgap reference and comparator design maintain threshold accuracy and timing integrity down to this level, preventing spurious resets or missed fault detection.

How does the watchdog timer function on MAX6729AKAVHD3+?

MAX6729AKAVHD3+ implements a dual-mode watchdog timer: a 35 s minimum startup period after each reset event (power-up, MR, or watchdog timeout), followed by a 1.12 s minimum normal-mode timeout. The timer clears on any rising or falling edge at WDI. If WDI remains static beyond the active timeout, RST asserts for 280 ms. Leaving WDI unconnected disables the watchdog via an internal 200 nA detection current source.