Analog Devices Inc./Maxim Integrated MAX6324HUT46

Overview

MAX6324HUT46 from Maxim Integrated is an open-drain microprocessor supervisory circuit with windowed (min/max) watchdog, manual reset input, and precision +4.63V reset threshold (±2.5% accuracy). It monitors VCC down to +1.2V, asserts RESET low on undervoltage or MR assertion, and pulses WDPO low for 1ms upon fast/slow watchdog faults. Used in automotive engine control units to detect firmware hangs during cold-cranking.

For engineers reviewing the MAX6324HUT46 datasheet, MAX6324HUT46 pinout, MAX6324HUT46 application, or MAX6324HUT46 equivalent, key selection criteria include its factory-trimmed 719ms fast timeout / 1.3s slow timeout, SOT23-6 open-drain RESET compatibility with bidirectional µP reset pins, guaranteed reset validity at VCC = +1.2V, and -40°C to +125°C operation for under-hood deployment.

Technical Context

The MAX6324HUT46 implements a dual-window watchdog using laser-trimmed timing: fast fault detection triggers if WDI falling edges occur within <719ms (tWD1 min), slow fault detection triggers if no WDI edge occurs beyond 1.3s (tWD2 max). Its internal comparator guarantees valid RESET output down to VCC = +1.2V, enabling reliable brownout detection during power ramp-down.

RESET is open-drain with 3.2mA sink capability at VCC = 4.25V and 1.2mA at VCC = 2.25V; WDPO is also open-drain, pulsed low for 1ms on fault detection. The MR input features internal pullup and 100ns glitch immunity, requiring only a 1µs minimum low pulse to assert reset.

Key Specifications

Pinout & Package

MAX6324HUT46 is housed in a 6-pin SOT23 package (JEDEC MO-178AA), with 1.3mm × 2.9mm footprint and 0.95mm height. Pin 1 is MR (manual reset input), 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 reset output).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6324HUT44 and TPS3808G33DBVR, the MAX6324HUT46 uniquely combines +4.63V precision reset, 719ms/1.3s windowed watchdog, and guaranteed operation down to VCC = +1.2V - making it the only option qualified for automotive cold-crank brownout supervision with dual-fault detection.

Availability

MAX6324HUT46 is available at Aetrix Electronics and suitable for automotive ECU design, industrial PLC development, and medical infusion pump certification requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6324HUT46 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 company specializing in high-performance analog, mixed-signal, and power management ICs for demanding industrial, automotive, and medical applications.

The MAX6324HUT46 belongs to the MAX6323/MAX6324 family of microprocessor supervisory circuits designed specifically for safety-critical embedded systems requiring windowed watchdog supervision and precise voltage monitoring over extreme temperatures.

FAQ

What is the exact reset threshold voltage of the MAX6324HUT46?

The MAX6324HUT46 has a nominal reset threshold of +4.63V, with ±2.5% accuracy over the full -40°C to +125°C temperature range. This value is laser-trimmed at the factory and specified in the Reset Threshold Range table of the datasheet. The "46" suffix explicitly denotes this +4.63V threshold, distinguishing it from other variants like UT44 (+4.38V) or UT31 (+3.08V). The MAX6324HUT46 guarantees valid RESET output down to VCC = +1.2V, ensuring deterministic behavior during deep brownout events.

How does the windowed watchdog function in the MAX6324HUT46?

The MAX6324HUT46 implements a true min/max (windowed) watchdog: it triggers WDPO on either a fast fault (WDI falling edges closer than 543ms–719ms apart) or a slow fault (no WDI edge for longer than 1.0s–1.3s). This dual-window architecture distinguishes between premature and delayed pulses, unlike single-timer watchdogs. The "H" suffix indicates the longest available fast timeout (719ms) and slow timeout (1.3s), optimized for applications requiring wide timing margins. The MAX6324HUT46 ignores the first WDI pulse after RESET deassertion to prevent false fast faults during startup.

Can the MAX6324HUT46 be used with a 3.3V microcontroller?

Yes, the MAX6324HUT46 supports interfacing with 3.3V microcontrollers via its open-drain RESET and WDPO outputs, which accept pullup voltages up to +6V. While its reset threshold is +4.63V (targeting 5V systems), the MR input operates with VIH = 0.75×VCC and VIL = 0.8V, allowing direct connection to 3.3V logic. However, for 3.3V supply monitoring, a different variant like MAX6324HUT31 (+3.08V threshold) would be more appropriate. The MAX6324HUT46's core functionality - including watchdog timing and reset assertion - remains fully operational regardless of the host µP's I/O voltage, provided proper level translation is applied to RESET/WDPO lines.

What is the minimum pulse width required on the MR input of the MAX6324HUT46?

The MR input of the MAX6324HUT46 requires a minimum low pulse width of 1µs to reliably assert the RESET output. This specification is guaranteed across the full -40°C to +125°C temperature range and is independent of VCC level. The MR pin features internal pullup and 100ns glitch immunity, meaning transients shorter than 100ns will not trigger reset. For robust manual reset implementation, a simple pushbutton to ground (with optional 0.1µF capacitor to ground for noise suppression) is sufficient - no external pullup resistor is needed. The MAX6324HUT46 holds RESET asserted for at least 100ms after MR returns high, ensuring adequate reset duration for any µP.

Does the MAX6324HUT46 support watchdog timeout adjustment via external components?

No, the MAX6324HUT46 does not support external adjustment of watchdog timeout periods. Its fast timeout (719ms/543ms) and slow timeout (1.3s/1.0s) are factory-laser-trimmed and fixed for the "H" variant; no resistors, capacitors, or configuration pins modify these values. This ensures timing accuracy and eliminates drift due to component tolerances or temperature. The "H" suffix is permanently encoded in the part number, indicating the specific trim set. If adjustable timeouts are required, alternative families such as the MAX6369 (programmable via resistor) or MAX16054 (I²C-configurable) should be considered - but the MAX6324HUT46 delivers guaranteed, production-ready timing without calibration overhead.