Analog Devices Inc./Maxim Integrated MAX6371KA+T

Overview

MAX6371KA+T from Maxim Integrated is a pin-selectable watchdog timer IC designed to supervise microprocessor activity in safety-critical embedded systems. It features open-drain active-low WDO output with 100ms pulse width, 60s fixed startup delay, and pin-selectable watchdog timeout periods from 1ms to 60s (min), operating across +2.5V to +5.5V supply. It is used in automotive and industrial controllers to detect software hangs and trigger system reset or interrupt.

For engineers reviewing the MAX6371KA+T datasheet, MAX6371KA+T pinout, MAX6371KA+T application, or MAX6371KA+T equivalent, key selection criteria include its fixed 60s startup delay, open-drain 100ms watchdog pulse, -40°C to +125°C operation, 8μA supply current, and SOT23-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX6371KA+T implements a precision analog/digital watchdog timer with three logic-controlled SET pins (SET0–SET2) that configure timing without power cycling. Its internal transition detector monitors WDI edges (≥100ns wide), clears the timer on each valid low-to-high or high-to-low edge, and asserts WDO after timeout - only after the 60s startup delay expires.

Unlike the MAX6369/MAX6370 family members, the MAX6371KA+T fixes startup delay at 60s while retaining full pin-selectability for watchdog timeout (eight options from 1ms to 60s). Its open-drain WDO requires an external pullup and sinks ≥1.2mA at 0.3V, enabling direct interface with µP reset inputs or interrupt controllers.

Key Specifications

Pinout & Package

MAX6371KA+T is housed in an 8-pin SOT23 package (package code K8SN+1, outline 21-0078), measuring 2.9mm × 1.6mm × 1.1mm, suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar watchdog timer applications.

Compared with MAX6372KA+T and MAX6369KA+T, the MAX6371KA+T uniquely combines fixed 60s startup delay with open-drain output - making it optimal for applications demanding guaranteed post-boot supervision window and multi-voltage reset interface capability.

Availability

MAX6371KA+T is available at Aetrix Electronics and suitable for automotive engine control, industrial PLCs, and medical infusion pumps requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6371KA+T 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 MAX6369–MAX6374 family was engineered specifically for high-reliability microprocessor supervision - delivering pin-configurable timing, ultra-low power, and AEC-Q100-qualified variants for mission-critical embedded systems.

FAQ

What is the startup delay behavior of the MAX6371KA+T?

The MAX6371KA+T has a fixed 60s startup delay - the watchdog timer does not begin counting its timeout period until 60 seconds after power-up or reset. During this interval, WDI transitions are ignored, ensuring full system initialization completes before supervision starts. This behavior is inherent to the MAX6371 variant and cannot be altered by SET pin configuration.

Does the MAX6371KA+T require an external pullup resistor on WDO?

Yes, the MAX6371KA+T features an open-drain WDO output and requires an external pullup resistor (typically 10kΩ to VCC) to establish a valid logic-high state when deasserted. Without this resistor, WDO remains floating and cannot reliably signal reset or interrupt conditions to downstream circuitry.

Can the MAX6371KA+T watchdog timeout be changed dynamically during operation?

Yes, the MAX6371KA+T allows dynamic timeout reconfiguration by changing the logic states of SET0, SET1, and SET2 pins while the device is powered. After a 300µs internal setup time, the new timeout value takes effect - but WDI must be strobed immediately before the change to avoid unintended timeout assertion.

What is the minimum WDI pulse width the MAX6371KA+T recognizes?

The MAX6371KA+T requires WDI input transitions (rising or falling edges) to have a minimum pulse width of 100ns to be reliably detected. Pulses narrower than this may be missed, leading to spurious WDO assertion - design must ensure µP GPIO toggling meets this timing constraint.

Is the MAX6371KA+T qualified for automotive applications?

No, the MAX6371KA+T is not AEC-Q100 qualified. Only the MAX6369KA/V+T and MAX6374KA/V+T variants in this family carry AEC-Q100 qualification. For automotive use, select those designated "/V+" versions - the MAX6371KA+T is rated for industrial (-40°C to +125°C) but lacks automotive stress testing certification.