Analog Devices Inc./Maxim Integrated MAX6865UK40D3S+T

Overview

The MAX6865UK40D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.000V reset threshold (±2.5%), 150ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP initialization during brownout or software fault conditions.

For engineers reviewing the MAX6865UK40D3S+T datasheet, MAX6865UK40D3S+T pinout, MAX6865UK40D3S+T application, or MAX6865UK40D3S+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 integrated 10kΩ MR pullup - all critical for low-power embedded system reliability.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a glitch-immune manual reset input with 250ns MR-to-reset delay and 1µs minimum pulse width, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). The internal reset timeout generator ensures deterministic deassertion timing after VCC recovery or MR release.

The MAX6865UK40D3S+T uses BiCMOS process technology (2848 transistors) and operates across –40°C to +85°C. Its push-pull active-high RESET output sources up to 500µA at VCC ≥ 2.38V (VOH ≥ 0.8×VCC) and sinks <25nA when deasserted, enabling direct interface with µP reset inputs without external components.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height, optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK40D3S+T, the MAX6865UK40D3S+T's active-high RESET simplifies interface to modern low-voltage µPs; versus TPS3836K33DBVR, its 170nA ICC and integrated watchdog deliver superior runtime and reliability in portable medical devices.

Availability

MAX6865UK40D3S+T is available at Aetrix Electronics and suitable for portable glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart hearing aids requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK40D3S+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6865UK40D3S+T belongs to Maxim's nanopower µP supervisory family, designed specifically for ultra-low-power battery-operated medical and portable electronics requiring guaranteed reset behavior and software fault recovery.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D3S+T?

The MAX6865UK40D3S+T has a factory-trimmed reset threshold of 4.000V with ±2.5% tolerance over –40°C to +85°C, as indicated by the "40" suffix in the part number. This value is guaranteed by design and validated across temperature and supply voltage ranges per the Electrical Characteristics table.

Does the MAX6865UK40D3S+T require external components for basic operation?

No, the MAX6865UK40D3S+T requires no external components for core functionality: it includes an internal 10kΩ pullup on MR, a precision voltage reference, and a timeout generator. Only a 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity in electrically noisy environments.

How does the watchdog timer in the MAX6865UK40D3S+T respond to software faults?

The MAX6865UK40D3S+T watchdog timer expires if the WDI input remains static (high or low) for longer than 3.3s (typ). It clears on any rising or falling edge, allowing flexible firmware integration - such as pulsing WDI once per main loop - to detect hangs in subroutines without requiring full toggling.

What is the minimum VCC voltage at which the MAX6865UK40D3S+T guarantees valid RESET output?

The MAX6865UK40D3S+T guarantees valid RESET output down to VCC = +1.1V, meaning the active-high RESET signal remains logically defined and capable of driving a µP reset input even during severe brownout conditions, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics sections.

Can the MAX6865UK40D3S+T be used with a microprocessor that has an active-low reset input?

No - the MAX6865UK40D3S+T provides only an active-high push-pull RESET output. To interface with an active-low µP reset input, use the pin-compatible MAX6864UK40D3S+T (active-low variant) or add a simple inverter stage; direct connection would invert reset logic and cause system malfunction.