Analog Devices Inc./Maxim Integrated MAX6865UK42D6S+T

Overview

The MAX6865UK42D6S+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 4.200V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog expiration-used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK42D6S+T datasheet, MAX6865UK42D6S+T pinout, MAX6865UK42D6S+T application, or MAX6865UK42D6S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients at 100mV overdrive, watchdog pulse detection as short as 150ns, and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a glitch-immune manual reset input with 1µs minimum pulse width and 200ns noise rejection, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). The internal 10kΩ MR pullup eliminates external components.

The reset logic combines asynchronous VCC monitoring and synchronous event triggering: RESET asserts immediately on VCC drop below 4.200V, MR low, or watchdog timeout-and remains asserted for ≥600ms after VCC recovery, MR deassertion, or watchdog reset. No external timing capacitor or resistor is required.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, -40°C to +85°C operating range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK42D6S+T and TPS3836K33DBVR, the MAX6865UK42D6S+T uniquely delivers active-high RESET, 170nA supply current, and integrated watchdog in one 5-pin SOT23-enabling compact, fail-safe, multi-year battery operation without compromise.

Availability

MAX6865UK42D6S+T is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld scanners, smart energy meters, and battery-backed data loggers requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK42D6S+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, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality for battery-constrained systems-prioritizing ultra-low ICC, guaranteed reset validity at low VCC, and robust watchdog supervision without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK42D6S+T?

The MAX6865UK42D6S+T has a factory-trimmed reset threshold of 4.200V, with ±2.5% tolerance over the full -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "42" corresponds to 4.200V nominal. The MAX6865UK42D6S+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK42D6S+T support active-high RESET output?

Yes, the MAX6865UK42D6S+T provides an active-high push-pull RESET output, as specified in its pin description and Selector Guide. Pin 1 outputs high during reset assertion and low when deasserted-directly compatible with µPs requiring active-high reset signaling. This distinguishes it from MAX6864 variants, which offer only active-low outputs.

What is the watchdog timeout period for the MAX6865UK42D6S+T?

Per the ordering code suffix "S", the MAX6865UK42D6S+T features a watchdog timeout period of 3.3s typical (1.5s min, 7.75s max), as defined in Table 3 (Watchdog Timeout). The timer resets on every rising or falling edge at WDI and triggers reset if WDI remains static beyond this interval-ensuring detection of firmware execution stalls.

Can the MAX6865UK42D6S+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK42D6S+T operates across 1.2V to 5.5V VCC, with guaranteed reset functionality down to VCC = +1.1V. Its supply current remains at 170nA typical even at 1.8V, and the RESET output remains valid and functional throughout this range-making it suitable for single-cell Li-ion and alkaline battery systems.

Is an external pullup resistor required for the MR input of the MAX6865UK42D6S+T?

No, the MAX6865UK42D6S+T includes an internal 10kΩ pullup resistor from MR to VCC, as documented in the Pin Description and Detailed Description sections. This eliminates the need for external components-MR can be left unconnected or tied to VCC when unused, and driven low via a momentary switch or CMOS logic without additional circuitry.