Analog Devices Inc./Maxim Integrated MAX6324BUT29

Overview

MAX6324BUT29 from Maxim Integrated is a microprocessor supervisory circuit with windowed (min/max) watchdog, open-drain RESET output, and factory-trimmed 3.00V ±2.5% reset threshold. It monitors VCC down to +1.2V, asserts RESET for ≥100ms after power recovery, and pulses WDPO low for 1ms upon fast or slow watchdog timeout faults. Used in automotive engine control units to detect firmware lockup during cold-cranking.

For engineers reviewing the MAX6324BUT29 datasheet, MAX6324BUT29 pinout, MAX6324BUT29 application, or MAX6324BUT29 equivalent, key selection criteria include its SOT23-6 open-drain RESET architecture, B-suffix 10ms/100ms watchdog timing window, guaranteed operation at -40°C to +125°C, and compatibility with bidirectional µP reset pins.

Technical Context

The MAX6324BUT29 implements a dual-window watchdog timer that detects both fast faults (WDI falling edges <10ms apart) and slow faults (no WDI edge >100ms), with WDPO pulsed low for 1ms on fault detection. Its internal reset comparator guarantees valid RESET assertion down to VCC = +1.2V, and the debounced MR input requires only a 1µs low pulse to trigger reset.

RESET is open-drain and requires an external pullup; WDPO is also open-drain and active only when RESET is deasserted. The device uses BiCMOS process (1371 transistors), draws 23µA typical supply current at 3.3V, and features 500pF minimum VCC bypassing for noise immunity in harsh automotive environments.

Key Specifications

Pinout & Package

SOT23-6 package (6-pin, 1.6mm × 2.9mm, 0.95mm height), lead-free compatible, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6324CUT29 and TPS3808G33DBVR, MAX6324BUT29 uniquely delivers 10ms/100ms windowed watchdog timing-essential for detecting subtle firmware anomalies in real-time embedded systems-while maintaining full compatibility with bidirectional reset architectures and extended temperature operation.

Availability

MAX6324BUT29 is available at Aetrix Electronics and suitable for automotive engine control, industrial PLCs, medical infusion pumps, and telecom remote radio units requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6324BUT29 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 medical applications.

The MAX6323/MAX6324 product line delivers highly accurate, temperature-stable supervisory circuits with advanced windowed watchdog functionality specifically for safety-critical embedded systems requiring robust firmware execution monitoring.

FAQ

What is the exact reset threshold voltage of MAX6324BUT29?

The MAX6324BUT29 has a factory-trimmed nominal reset threshold of 3.00V with ±2.5% accuracy over -40°C to +125°C. This corresponds to a guaranteed range of 2.93V to 3.08V at +25°C and maintains tight tolerance across temperature, making it ideal for precise 3.3V supply monitoring in automotive and industrial systems where brownout detection must avoid false triggers.

How does the B-suffix in MAX6324BUT29 define its watchdog behavior?

The B-suffix in MAX6324BUT29 specifies a 10ms fast timeout and 100ms slow timeout window for the windowed watchdog function. This means the device expects WDI falling edges to occur no sooner than 10ms apart (to avoid fast-fault detection) and no later than 100ms apart (to avoid slow-fault detection). This timing window is laser-trimmed at manufacture and cannot be adjusted externally.

Can MAX6324BUT29 drive a reset line directly without a pullup resistor?

No, MAX6324BUT29 cannot drive a reset line directly without a pullup resistor because its RESET output is open-drain. An external pullup resistor (typically 4.7kΩ to 10kΩ) must connect RESET to a logic-compatible supply (up to +6V) to ensure proper high-state voltage levels. Without this pullup, RESET remains floating when deasserted, risking undefined µP behavior.

What is the minimum VCC voltage at which MAX6324BUT29 guarantees valid RESET assertion?

MAX6324BUT29 guarantees valid RESET assertion down to VCC = +1.2V. Below this voltage, the internal circuitry cannot sink sufficient current to maintain a solid logic-low state on the open-drain RESET output. This specification ensures deterministic reset behavior during deep brownout events common in automotive stop-start systems and industrial power interruptions.

Is MAX6324BUT29 compatible with bidirectional microcontroller reset pins?

Yes, MAX6324BUT29 is fully compatible with bidirectional µP reset pins (e.g., Motorola 68HC11, certain ARM Cortex-M variants) due to its open-drain RESET output. When combined with a single shared pullup resistor, both the MAX6324BUT29 and the µP can assert reset on the same line-enabling coordinated system recovery without additional logic or isolation components.