Analog Devices Inc./Maxim Integrated MAX6865UK44D5L+T

Overview

The MAX6865UK44D5L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.266V reset threshold (±2.5%), 300ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable power-on reset and code-execution error recovery.

For engineers reviewing the MAX6865UK44D5L+T datasheet, MAX6865UK44D5L+T pinout, MAX6865UK44D5L+T application, or MAX6865UK44D5L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with CMOS-level MR/WDI inputs.

Technical Context

The MAX6865UK44D5L+T implements a dual-monitoring architecture: a precision voltage detector with 2.5% threshold hysteresis and a watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 209s (typ). Its internal 10kΩ MR pullup enables direct switch-to-GND interfacing without external components.

It uses BiCMOS process technology (2848 transistors) to achieve nanoscale quiescent current while maintaining robust noise immunity-guaranteed operation across -40°C to +85°C and valid reset assertion even during VCC brownout to 1.1V. The device asserts RESET high when VCC falls below 4.266V, MR is pulled low, or WDI stalls.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK44D5S+T and TPS3837K33DBVR, the MAX6865UK44D5L+T uniquely combines long-interval watchdog supervision (209s), precise 4.266V threshold, and active-high push-pull RESET in one nanopower package-enabling single-chip reliability for battery-critical medical and portable systems.

Availability

MAX6865UK44D5L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and feature cell phones requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK44D5L+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 and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functions-including voltage monitoring, manual reset, and configurable watchdog timers-for ultra-low-power portable and battery-operated systems.

FAQ

What is the exact reset threshold voltage of the MAX6865UK44D5L+T?

The MAX6865UK44D5L+T has a factory-trimmed reset threshold of 4.266V, with guaranteed tolerance of ±2.5% (min 4.193V, max 4.408V) across -40°C to +85°C. This value corresponds to the "44" suffix in the part number per Maxim's Threshold Suffix Guide and is optimized for monitoring 3.3V or 5V rails with margin.

Does the MAX6865UK44D5L+T require external components for basic operation?

No, the MAX6865UK44D5L+T operates autonomously with zero external components: it includes an internal 10kΩ pullup on MR, needs no timing capacitor for reset or watchdog, and only requires a 0.1µF bypass capacitor on VCC for noise immunity. Its push-pull active-high RESET output drives µP reset pins directly.

How does the watchdog timer in the MAX6865UK44D5L+T respond to software activity?

The MAX6865UK44D5L+T watchdog timer clears on any rising or falling edge at the WDI pin-not on level transitions-and expires only if WDI remains static for ≥209s (typ). This edge-triggered behavior allows flexible software placement of WDI toggles, including within interrupt service routines or main loop entries.

What is the minimum VCC voltage at which the MAX6865UK44D5L+T guarantees valid RESET assertion?

The MAX6865UK44D5L+T guarantees valid RESET assertion down to VCC = +1.1V, as specified in the Electrical Characteristics table. Below this voltage, RESET may become indeterminate; however, most µPs cease operation above 1.1V, making this specification sufficient for brownout protection in real-world systems.

Is the MAX6865UK44D5L+T pin-compatible with other devices in the MAX68xx family?

Yes, the MAX6865UK44D5L+T uses the standard 5-pin SOT23-5 package and shares identical pinout (RESET, GND, MR, WDI, VCC) with MAX6864/MAX6866/MAX6867–MAX6869 variants. This allows drop-in substitution within the same functional group, provided watchdog timeout (S vs. L) and RESET polarity match system requirements.