Analog Devices Inc./Maxim Integrated MAX6865UK28D3L+T

Overview

The MAX6865UK28D3L+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 (±2.5%), 150ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK28D3L+T datasheet, MAX6865UK28D3L+T pinout, MAX6865UK28D3L+T application, or MAX6865UK28D3L+T equivalent, key selection criteria include its active-high push-pull RESET output, guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, and compatibility with 1.2V–5.5V supply rails in space-constrained, low-power embedded designs.

Technical Context

This device implements a dual-trigger reset architecture: one path responds to VCC falling below 2.800V (with 0.5% hysteresis), another to MR assertion, and a third to WDI inactivity exceeding 209s (typ). The internal watchdog timer clears on any WDI edge, MR assertion, or RESET activation - preventing false timeouts during system recovery.

Its push-pull active-high RESET output drives high (≥0.8×VCC) when asserted and deasserts low (≤0.3V) when inactive, eliminating external pullup components. The MR input includes a 10kΩ internal pullup and rejects <200ns glitches, enabling direct connection to momentary switches without debounce circuitry.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint-compatible with industry-standard 5-lead SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK28D3L+T, the MAX6864UK28D3L+T offers identical supervision timing but requires active-low µP interface, while the TPS3837MPDBVR trades nanopower operation and watchdog capability for tighter threshold tolerance and lower unit cost - making it viable only in non-battery or non-safety contexts.

Availability

MAX6865UK28D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient loggers, industrial scanners, and smart smoke detectors requiring stable component supply across extended temperature ranges and multi-year battery life.

Supply support for MAX6865UK28D3L+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 precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX68xx family was designed specifically for ultra-low-power microprocessor supervision in battery-operated medical and portable equipment, emphasizing nanoscale current consumption, robust reset timing, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D3L+T?

The MAX6865UK28D3L+T has a factory-trimmed reset threshold of 2.800V with ±2.5% tolerance over -40°C to +85°C. This value is encoded in the "28" suffix per Maxim's Threshold Suffix Guide (Table 2), and is verified across temperature and supply voltage variations in the Electrical Characteristics table.

Does the MAX6865UK28D3L+T require external components for basic operation?

No - the MAX6865UK28D3L+T operates autonomously with only a 0.1µF VCC bypass capacitor recommended. It integrates a 10kΩ MR pullup resistor, precise voltage reference, reset timer, and watchdog circuitry, eliminating discrete resistors, capacitors, or comparators required by discrete supervisory solutions.

How does the watchdog timer in the MAX6865UK28D3L+T behave during reset assertion?

While RESET is asserted (high), the MAX6865UK28D3L+T watchdog timer is disabled and does not count. It resumes timing only after RESET deasserts. This prevents race conditions during recovery and ensures the watchdog monitors only active firmware execution - a critical behavior confirmed in the Detailed Description section.

Can the MAX6865UK28D3L+T operate reliably at VCC = 1.2V?

Yes - the MAX6865UK28D3L+T is fully specified from VCC = 1.2V to 5.5V. Its 170nA supply current, 2.800V threshold detection, and RESET output functionality (VOH ≥0.8×VCC, VOL ≤0.3V) are all guaranteed at 1.2V, enabling use in modern ultra-low-voltage microcontrollers and sensors.

What is the purpose of the "L" suffix in MAX6865UK28D3L+T?

The "L" suffix in MAX6865UK28D3L+T specifies the watchdog timeout period: 209s typical (95s min, 487s max), per Table 3. This distinguishes it from the "S" suffix (3.3s typical), allowing selection of long-interval supervision for infrequent firmware tasks without modifying hardware design.