Analog Devices Inc./Maxim Integrated MAX6324HUT29

Overview

MAX6324HUT29 from Maxim Integrated is an open-drain µP supervisory circuit with min/max (windowed) watchdog, manual reset input, and precision +2.93V reset threshold (±2.5% accuracy). It monitors VCC down to +1.2V, asserts RESET low on brownout or MR activation, and pulses WDPO low for 1ms upon fast/slow watchdog timeout faults. Used in automotive engine control units for fault-tolerant microprocessor supervision.

For engineers reviewing the MAX6324HUT29 datasheet, MAX6324HUT29 pinout, MAX6324HUT29 application, or MAX6324HUT29 equivalent, key selection criteria include its factory-trimmed 719ms fast / 1.3s slow watchdog window, open-drain RESET output compatibility with bidirectional µP reset pins, guaranteed reset validity at VCC = +1.2V, and operation across –40°C to +125°C.

Technical Context

The MAX6324HUT29 implements a dual-window watchdog timer that detects both premature (faster than 719ms) and delayed (slower than 1.3s) falling edges on WDI, independent of RESET state. Its internal comparator guarantees reset assertion until VCC rises above 2.93V and remains asserted ≥100ms after recovery.

RESET is open-drain with leakage <0.4µA at VCC = 5.5V and sink capability of 1.2mA at VCC = 2.25V; WDPO is also open-drain, pulsed low for 1ms (typ) on fault detection. The device uses BiCMOS process (1371 transistors) and draws only 23µA typical supply current at 3.3V.

Key Specifications

Pinout & Package

MAX6324HUT29 is housed in a 6-pin SOT23 package (2.9mm × 1.6mm × 1.1mm), RoHS-compliant and available in lead-free (+T) variant. Pin 1 is MR (manual reset), Pin 2 is GND, Pin 3 is WDI (watchdog input), Pin 4 is VCC, Pin 5 is WDPO (watchdog pulse output), and Pin 6 is RESET (open-drain active-low).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6324HUT31, MAX6324HUT29 offers tighter alignment with 3.0V supply rails and greater brownout headroom; compared with TPS3808G33DBVR, it delivers critical safety-enhancing min/max watchdog functionality and dedicated fault pulse output absent in the TI part.

Availability

MAX6324HUT29 is available at Aetrix Electronics and suitable for automotive engine control, industrial PLC modules, medical infusion pumps, railway signaling interfaces, and high-reliability embedded systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6324HUT29 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 medical applications, emphasizing reliability, low power, and high integration.

The MAX6323/MAX6324 product line delivers fault-tolerant microprocessor supervision with windowed watchdog timers, targeting safety-critical systems where standard single-threshold reset ICs cannot detect subtle timing anomalies in firmware execution.

FAQ

What is the exact reset threshold voltage of MAX6324HUT29 and how is it trimmed?

The MAX6324HUT29 has a nominal reset threshold of +2.93V, laser-trimmed to ±2.5% accuracy over –40°C to +125°C. This value is fixed at wafer test and corresponds to the "UT29" suffix per Maxim's ordering nomenclature. The trim ensures precise matching to 3.0V supply rails while maintaining sufficient margin for ripple and thermal drift, eliminating need for external calibration components in the MAX6324HUT29 design.

Does MAX6324HUT29 support interfacing with microcontrollers that have bidirectional reset pins?

Yes, the MAX6324HUT29 features an open-drain RESET output, enabling direct wired-OR connection to bidirectional µP reset pins such as those found on Motorola 68HC11 or certain ARM Cortex-M devices. A single pullup resistor suffices for shared reset bus operation, allowing either the MAX6324HUT29 or the µP to assert reset - a capability not available with push-pull reset ICs and essential for flexible system-level fault recovery in the MAX6324HUT29 implementation.

What are the watchdog timeout values configured for MAX6324HUT29?

The MAX6324HUT29 is factory-configured with a fast watchdog timeout of 719ms (min) and a slow watchdog timeout of 1.3s (min), corresponding to the "H" suffix in its part number. These values define the valid window for WDI falling edges: pulses arriving faster than 719ms or slower than 1.3s trigger a 1ms WDPO pulse. Both timeouts are laser-trimmed and stable over temperature, making the MAX6324HUT29 suitable for applications requiring precise execution timing validation.

Can MAX6324HUT29 operate reliably during severe supply brownouts?

Yes, the MAX6324HUT29 guarantees valid RESET output down to VCC = +1.2V, ensuring deterministic reset assertion even during deep brownouts common in automotive cold-cranking or industrial power sag events. Below +1.2V, the internal circuitry ceases sinking current - but because the MAX6324HUT29's open-drain RESET remains high-impedance rather than floating, external pullup maintains defined logic state, preserving system integrity longer than competing supervisors.

Is there a lead-free version of MAX6324HUT29 available?

Yes, the lead-free version of MAX6324HUT29 is ordered as MAX6324HUT29+T, replacing the standard "-T" suffix with "+T". This variant complies with RoHS Directive 2011/65/EU and uses matte-tin lead finish on the SOT23-6 package. Both versions share identical electrical specifications, temperature rating (–40°C to +125°C), and mechanical dimensions - the MAX6324HUT29+T is a direct drop-in replacement for legacy leaded assemblies requiring environmental compliance.