Analog Devices Inc./Maxim Integrated MAX6814XK+T

Overview

MAX6814XK+T from Maxim Integrated is a low-power, 5-pin SC70 watchdog timer IC that monitors microprocessor software execution by detecting WDI signal transitions. It features a 1.6s typical watchdog timeout period, 140ms minimum active-low push-pull WDO pulse, 4µA supply current at 2.5V, and operates across –40°C to +85°C. It is used in critical µP monitoring for embedded controllers where reliable fault detection without external components is required.

For engineers reviewing the MAX6814XK+T datasheet, MAX6814XK+T pinout, MAX6814XK+T application, or MAX6814XK+T equivalent, key selection considerations include undervoltage lockout threshold (2.19V), WDI input timing tolerance (50ns pulse width), WDO output drive capability (1.2mA sink), temperature-stable timeout behavior, and RoHS-compliant SC70-5 packaging with no-lead finish.

Technical Context

The MAX6814XK+T implements a monolithic BiCMOS watchdog timer with internal edge-detection logic on the WDI pin, automatically clearing the 1.6s timeout counter on rising or falling edges. Its WDO output is push-pull, actively driven low for ≥140ms upon timeout or UVLO recovery - not open-drain.

It integrates undervoltage lockout (UVLO) at 2.19V, ensuring WDO remains asserted during brown-out conditions and releases only after VCC exceeds threshold plus tPP delay. The device requires no external RC network and disables watchdog functionality when WDI is left unconnected or tri-stated, per internal 7/8–1/8 duty-cycle driver.

Key Specifications

Pinout & Package

MAX6814XK+T is housed in a 5-pin SC70 package (outline X5+1, land pattern 90-0188), measuring 2.0mm × 1.25mm × 0.9mm, with RoHS-compliant matte-tin lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6814XK+T, MAX6361KA+T trades lower integration for cost, while TPS3808G12DBVR offers timeout adjustability at the expense of added passive components - MAX6814XK+T delivers fixed, guaranteed timing with zero external parts and best-in-class low-power operation.

Availability

MAX6814XK+T is available at Aetrix Electronics and suitable for industrial embedded controllers, critical microprocessor monitoring, and intelligent instruments requiring stable component supply over extended temperature ranges and long production lifecycles.

Supply support for MAX6814XK+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 industrial, computing, and communications applications.

The MAX6814XK+T belongs to Maxim's supervisory and watchdog timer product line, engineered specifically for fail-safe microprocessor monitoring in space- and power-constrained embedded systems.

FAQ

What is the watchdog timeout period for MAX6814XK+T, and how is it affected by temperature?

The MAX6814XK+T has a typical watchdog timeout period of 1.6s, with min/max values of 1.12s and 2.40s over –40°C to +85°C. Characterization data shows minimal drift: from 1.40s at –40°C to 1.75s at +85°C. This stability ensures predictable fault response across industrial operating conditions without recalibration. The MAX6814XK+T datasheet specifies full performance across this range, and the timeout is internally generated - no external components affect its accuracy.

Does MAX6814XK+T require external components to operate?

No, MAX6814XK+T operates autonomously with no external resistors or capacitors required. Its 1.6s timeout, 140ms WDO pulse, and UVLO threshold are all factory-trimmed and internally generated. The only connections needed are VCC, GND, WDI (toggled by µP), and WDO (driving reset logic). Leaving WDI unconnected disables the watchdog - no pull-up/down resistors are necessary. This simplifies design and improves long-term reliability versus RC-based solutions.

What is the function of Pin 3 (N.C.) on MAX6814XK+T, and how should it be handled?

Pin 3 on MAX6814XK+T is labeled N.C. (No Connection) and is internally unconnected. It may be left floating or tied to VCC per PCB layout convenience - neither choice affects device operation. Maxim's datasheet explicitly permits either option and confirms no electrical interaction occurs. This flexibility aids routing in dense SC70 layouts without introducing noise coupling or unintended bias paths. Always verify netlist exclusions for Pin 3 during CAD review to prevent accidental shorts.

How does MAX6814XK+T behave during power-up and brown-out conditions?

During power-up, MAX6814XK+T asserts WDO low until VCC exceeds the 2.19V UVLO threshold, then waits the full 140ms pulse period before releasing WDO high - ensuring clean µP reset sequencing. During brown-out, WDO reasserts low immediately upon VCC dropping below UVLO and remains low for ≥140ms after recovery. This dual-mode behavior prevents spurious resets and guarantees robust power-supply supervision without external circuitry. The MAX6814XK+T integrates this functionality natively.

Can MAX6814XK+T be used with both 3.3V and 5V microprocessors?

Yes, MAX6814XK+T supports an operating voltage range of 2.25V to 5.5V, making it compatible with both 3.3V and 5V µP I/O domains. Its WDI input accepts logic thresholds referenced to VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), and WDO output provides rail-to-rail push-pull drive - VOH ≥ 0.8×VCC and VOL ≤ 0.3V. This eliminates level-shifting needs. When interfacing with a 3.3V µP, VCC = 3.3V yields VIH ≈ 2.31V and VOL ≤ 0.3V, ensuring solid noise margins. The MAX6814XK+T maintains full specification across this range.