Analog Devices Inc./Maxim Integrated MAX6865UK28D1L+T

Overview

The MAX6865UK28D1L+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 2.800V reset threshold (suffix D1L), 10ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. 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 MAX6865UK28D1L+T datasheet, MAX6865UK28D1L+T pinout, MAX6865UK28D1L+T application, or MAX6865UK28D1L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, 200ns MR glitch rejection, and compatibility with 1.2V–5.5V supply rails in space-constrained portable systems.

Technical Context

This device implements a precision voltage monitor with ±2.5% reset threshold accuracy over -40°C to +85°C, a digital watchdog timer cleared by WDI edges (min pulse width 150ns), and a fixed 10ms reset timeout after VCC recovery or MR deassertion. Its internal 10kΩ MR pullup and open-drain/push-pull output options support direct CMOS interfacing without external components.

The MAX6865UK28D1L+T belongs to the MAX6864–MAX6869 variant group with active-high push-pull RESET, manual reset input, and watchdog functionality. It uses BiCMOS process technology (2848 transistors) and guarantees operation with VCC as low as 1.2V while maintaining 170nA quiescent current at 2.5V.

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 MAX6864UK28D1S+T and TPS3836K33DBVR, the MAX6865UK28D1L+T uniquely balances ultra-low power (170nA), precise 2.8V threshold, short 10ms reset hold, and long 209s watchdog - making it optimal for extended-life portable medical devices requiring both power efficiency and robust firmware supervision.

Availability

MAX6865UK28D1L+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and wearable biosensors requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK28D1L+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 communications markets.

The MAX6864–MAX6869 product line delivers nanopower supervisory circuits optimized for battery-critical portable healthcare and IoT edge devices, integrating voltage monitoring, manual reset, and configurable watchdog timers in minimal SOT23 footprints.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D1L+T?

The MAX6865UK28D1L+T has a factory-trimmed reset threshold of 2.800V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "28" corresponds to 2.800V nominal. The MAX6865UK28D1L+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK28D1L+T support active-high or active-low reset output?

The MAX6865UK28D1L+T provides an active-high push-pull RESET output, as defined in its pin description and Selector Guide. Pin 1 drives high during reset assertion (e.g., when VCC falls below 2.800V, MR is pulled low, or the watchdog expires) and returns low after the 10ms timeout. This configuration eliminates the need for an external pullup resistor and simplifies interfacing with µPs that require active-high reset signals.

What is the watchdog timeout period for the MAX6865UK28D1L+T?

The MAX6865UK28D1L+T features a watchdog timeout period of 209s typical (with ±50% variation), indicated by the "L" suffix in its part number. This long timeout is specifically designed for firmware with extended idle or calibration phases, such as in glucose monitors or wearable sensors. The timer resets on any edge (rising or falling) at the WDI pin and remains disabled while RESET is asserted.

Can the MAX6865UK28D1L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK28D1L+T is fully specified to operate from VCC = 1.2V to 5.5V. Its supply current remains at 170nA typical even at 1.2V, and the RESET output is guaranteed valid down to VCC = +1.1V. This allows seamless integration with ultra-low-voltage LDOs and energy-harvesting power supplies common in next-generation portable medical devices.

How does the MAX6865UK28D1L+T handle short VCC transients?

The MAX6865UK28D1L+T is immune to VCC transients ≤40µs in duration when the overdrive is 100mV above its 2.800V threshold, as shown in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph. This built-in immunity prevents false resets caused by switching noise or load-step disturbances, eliminating the need for additional filtering components in compact PCB layouts.