Analog Devices Inc./Maxim Integrated MAX6865UK29D1S+T

Overview

MAX6865UK29D1S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold (suffix '29'), 10ms minimum reset timeout (D1), and watchdog timer with 3.3s typical timeout (S suffix). It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout, power-up, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK29D1S+T datasheet, MAX6865UK29D1S+T pinout, MAX6865UK29D1S+T application, or MAX6865UK29D1S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, pin-selectable reset delay absence (fixed D1), and compatibility with 1.2V–5.5V supply rails in space-constrained embedded systems.

Technical Context

The MAX6865UK29D1S+T integrates a precision voltage monitor, manual reset input (MR), and watchdog timer with edge-triggered WDI input that clears on rising/falling transitions. Its internal reset timeout generator ensures minimum 10ms assertion after VCC recovery, MR deassertion, or watchdog expiration - independent of supply voltage within 1.2V–5.5V range.

It uses BiCMOS process (2848 transistors) for nanoscale leakage control, enabling stable operation across –40°C to +85°C. The active-high push-pull RESET output is referenced to VCC and sinks ≤0.3V at 1.2mA load, while MR features 10kΩ internal pullup and 1µs minimum pulse width tolerance.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and STM6823RWDY6F, the MAX6865UK29D1S+T uniquely combines ultra-low ICC, integrated watchdog with 3.3s timeout, and precise 2.925V threshold - making it optimal for long-life, safety-critical portable medical devices requiring both voltage and software execution supervision.

Availability

MAX6865UK29D1S+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and low-power wireless health sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK29D1S+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 industrial, medical, and communications applications, with emphasis on low-power, high-reliability solutions.

The MAX68xx family targets nanopower supervisory needs in space- and energy-constrained embedded systems, specifically addressing battery longevity, brownout resilience, and firmware crash recovery in portable healthcare electronics.

FAQ

What is the exact reset threshold voltage of MAX6865UK29D1S+T?

The MAX6865UK29D1S+T has a factory-trimmed reset threshold of 2.925V, with ±2.5% tolerance over –40°C to +85°C. This value is defined by the '29' suffix per Maxim's Threshold Suffix Guide (Table 2), and is guaranteed valid down to VCC = +1.1V - ensuring reliable brownout detection even as battery voltage declines in portable medical devices using the MAX6865UK29D1S+T.

Does MAX6865UK29D1S+T support active-low reset output?

No, the MAX6865UK29D1S+T provides an active-high push-pull RESET output only, as confirmed by its pin configuration (Pin 1 = RESET, functional description for MAX6865 variant), Selector Guide entry, and Typical Operating Circuit. It cannot be configured for active-low operation; for that function, designers must select MAX6864UK29D1S+T (active-low push-pull) or MAX6866UK29D1S+T (active-low open-drain) instead of the MAX6865UK29D1S+T.

What is the watchdog timeout behavior of MAX6865UK29D1S+T?

The MAX6865UK29D1S+T features a watchdog timer with 3.3s typical timeout (S suffix), clearing on any WDI edge (rising or falling) and asserting RESET if WDI remains static beyond that period. The timer pauses while RESET is asserted and resumes counting upon deassertion. This behavior is documented in the Watchdog Timer section, Electrical Characteristics table (tWD = 1.5s/3.3s/7.75s), and Figure 3 timing diagram - critical for validating firmware heartbeat intervals in the MAX6865UK29D1S+T.

Can MAX6865UK29D1S+T operate from a 1.5V supply?

Yes, the MAX6865UK29D1S+T operates from 1.2V to 5.5V, including 1.5V nominal supplies. At 1.5V, its 2.925V reset threshold remains valid (VTH > VCC), so it will assert RESET continuously - which is intentional for undervoltage lockout. For 1.5V systems, the MAX6865UK29D1S+T is only suitable when monitoring a higher rail (e.g., 3.3V LDO output), not the 1.5V source itself. This behavior is specified in the Absolute Maximum Ratings and Electrical Characteristics tables for the MAX6865UK29D1S+T.

Is MAX6865UK29D1S+T pin-compatible with other MAX68xx devices?

The MAX6865UK29D1S+T shares the same 5-pin SOT23 package and pinout (RESET/MR/WDI/GND/VCC) with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869 - all of which place WDI on Pin 4 and RESET on Pin 1. However, it is not pin-compatible with MAX6861–MAX6863 (CT on Pin 1) or MAX6854–MAX6856 (no WDI). This compatibility is confirmed in the Pin Configurations diagram and Selector Guide - enabling drop-in replacement among the WDI-equipped MAX686x variants, including the MAX6865UK29D1S+T.