Analog Devices Inc./Maxim Integrated MAX6865UK31D5L+T

Overview

The MAX6865UK31D5L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.075V reset threshold (suffix '31'), 600ms minimum reset timeout (D5), and 209s typical watchdog timeout (L). It monitors VCC, responds to manual reset (MR) input, and triggers reset on watchdog expiration - designed for battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK31D5L+T datasheet, MAX6865UK31D5L+T pinout, MAX6865UK31D5L+T application, or MAX6865UK31D5L+T equivalent, this page delivers verified functional identity, exact reset timing values, watchdog behavior under temperature variation, MR glitch rejection (200ns), and guaranteed reset validity down to VCC = +1.1V - all confirmed for this specific variant.

Technical Context

The MAX6865UK31D5L+T integrates voltage monitoring, manual reset assertion, and a watchdog timer with 209s typical timeout (L suffix) into a single BiCMOS IC. Its internal architecture includes a precision bandgap reference for ±2.5% reset threshold accuracy, a digital timeout counter for D5 (600ms min) reset hold time, and edge-sensitive WDI detection capable of recognizing 150ns pulses.

This variant belongs to the MAX6864–MAX6869 series with active-high push-pull RESET output, MR input with 10kΩ internal pullup, and no CT pin. Unlike MAX6861–MAX6863, it lacks pin-selectable timeout; unlike MAX6854/MAX6855, it includes watchdog functionality and uses L-suffix watchdog timing (95–487s range).

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (indicated by '+T' suffix), footprint-compatible with industry-standard 5-lead SOT23.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK31D5L+T, the S-suffix variant offers faster watchdog response but less margin for long idle periods, while TPS3837K33DBVR eliminates watchdog capability entirely and consumes ~9x more current - making MAX6865UK31D5L+T uniquely suitable for long-life, safety-critical portable medical supervision.

Availability

MAX6865UK31D5L+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and smart inhalers requiring stable component supply across extended production lifecycles and strict medical-grade traceability.

Supply support for MAX6865UK31D5L+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, medical, and communications applications.

The MAX6865UK31D5L+T belongs to the nanopower µP supervisory family engineered specifically for battery-constrained portable medical and wearable electronics requiring guaranteed reset behavior and ultra-low quiescent current.

FAQ

What is the exact reset threshold voltage of the MAX6865UK31D5L+T?

The MAX6865UK31D5L+T has a factory-trimmed reset threshold of 3.075V, with ±2.5% tolerance over -40°C to +85°C. This value is defined by the '31' suffix per Maxim's Threshold Suffix Guide (Table 2), and is guaranteed valid down to VCC = +1.1V - ensuring robust brownout detection in low-voltage medical sensors powered by aging batteries.

Does the MAX6865UK31D5L+T include a watchdog timer, and what is its timeout behavior?

Yes, the MAX6865UK31D5L+T includes a watchdog timer with L-suffix timing: 95s (min), 209s (typ), and 487s (max) timeout. The timer clears on any rising or falling edge at WDI and expires only if WDI remains static beyond that period. Unlike S-suffix variants, the L version is optimized for infrequent firmware supervision in devices with long sleep intervals, such as glucose monitors.

What type of reset output does the MAX6865UK31D5L+T provide, and how is it configured?

The MAX6865UK31D5L+T provides an active-high push-pull RESET output (Pin 1), meaning it drives high during reset assertion and low when deasserted. It is referenced to VCC and requires no external pullup resistor. This configuration directly interfaces with µPs expecting active-high reset inputs - eliminating level-shifting components and simplifying PCB layout in space-constrained portable designs.

How does the manual reset (MR) input function on the MAX6865UK31D5L+T?

The MR input (Pin 3) is active-low with an internal 10kΩ pullup to VCC. Driving MR low initiates reset for the full 600ms timeout (D5), regardless of VCC level. It accepts CMOS logic levels, rejects <200ns glitches, and requires only a momentary switch to GND - no external debounce circuitry needed. Leaving MR unconnected defaults to inactive (high), enabling safe integration in automated test fixtures.

Is the MAX6865UK31D5L+T compatible with other SOT23-5 supervisory ICs, and what are key layout considerations?

Yes, the MAX6865UK31D5L+T uses standard 5-pin SOT23-5 footprint and shares pinout compatibility with MAX6864–MAX6869 variants. Critical layout practices include placing a 0.1µF ceramic capacitor between VCC and GND as close as possible to Pin 5, routing WDI away from noisy traces, and avoiding vias under the thermal pad (none present in SOT23-5). No thermal pad or exposed die attach is used in this package.