Analog Devices Inc./Maxim Integrated MAX6865UK44D4S+T

Overview

The MAX6865UK44D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 4.266V reset threshold (suffix "44"), 1200ms minimum reset timeout (suffix "D4"), and integrated watchdog timer with 3.3s typical timeout (suffix "S"). It monitors VCC, responds to manual reset (MR), and asserts reset on voltage drop, MR assertion, or watchdog expiration - used in battery-powered medical and portable electronics requiring reliable power-on reset and code-execution monitoring.

For engineers reviewing the MAX6865UK44D4S+T datasheet, MAX6865UK44D4S+T pinout, MAX6865UK44D4S+T application, or MAX6865UK44D4S+T equivalent, this page delivers verified electrical parameters, functional pin roles, real-world use cases in glucose monitors and PDAs, and validated alternative parts for design continuity and sourcing flexibility.

Technical Context

The MAX6865UK44D4S+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 4.266V (±2.5%), when MR is pulled low, or when the watchdog input (WDI) remains static beyond 3.3s (typ). Its internal timer guarantees reset remains asserted for ≥1200ms after VCC recovery and MR deassertion.

It features push-pull active-high RESET output referenced to VCC, 10kΩ internal MR pullup, 150ns WDI pulse detection capability, and guaranteed reset validity down to VCC = +1.1V - enabling robust operation across brownout and low-voltage conditions in portable systems.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK44D4S+T and TPS3837K33DBVR, the MAX6865UK44D4S+T uniquely combines active-high reset, nanopower consumption, and integrated watchdog - making it optimal for next-gen portable medical and consumer devices demanding both safety and longevity.

Availability

MAX6865UK44D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and PDAs requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK44D4S+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 MAX6865UK44D4S+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for battery-critical portable electronics requiring guaranteed reset behavior, ultra-low quiescent current, and integrated watchdog protection.

FAQ

What is the reset threshold voltage of the MAX6865UK44D4S+T?

The MAX6865UK44D4S+T has a factory-trimmed reset threshold voltage of 4.266V, with a tolerance of ±2.5% (min 4.193V, max 4.408V). This value is encoded in the "44" suffix per Maxim's Threshold Suffix Guide and is specified across the full operating temperature range of -40°C to +85°C. The MAX6865UK44D4S+T uses this threshold to monitor 3.3V or 5V rails with margin for noise and drift.

Does the MAX6865UK44D4S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK44D4S+T includes an integrated watchdog timer with a typical timeout of 3.3s, indicated by the "S" suffix in the part number. It monitors transitions on the WDI pin and triggers reset if no edge is detected within that period. The timer clears on any rising or falling edge, MR assertion, or reset assertion - ensuring responsive firmware supervision without false timeouts.

What type of reset output does the MAX6865UK44D4S+T provide?

The MAX6865UK44D4S+T provides a push-pull active-high RESET output (pin 1), meaning it drives high during reset assertion and pulls low when deasserted. Unlike open-drain variants, it requires no external pullup resistor and interfaces directly to µP reset inputs expecting active-high logic. This configuration is confirmed in the MAX6865 pin description and functional diagram.

What is the minimum reset timeout period for the MAX6865UK44D4S+T?

The MAX6865UK44D4S+T has a minimum reset timeout period of 1200ms, denoted by the "D4" suffix. This timeout begins after VCC rises above the 4.266V threshold and MR is deasserted, ensuring sufficient time for power rail stabilization and µP internal initialization before release from reset - critical for complex SoCs and peripherals.

Is the MAX6865UK44D4S+T compatible with 1.8V supply systems?

Yes, the MAX6865UK44D4S+T operates across a VCC range of 1.2V to 5.5V and is fully specified at 1.8V, where its typical supply current is 170nA. Its reset output remains valid down to VCC = +1.1V, and its MR and WDI inputs accept logic thresholds scaled to VCC (e.g., VIH = 0.7 × VCC). This makes the MAX6865UK44D4S+T suitable for modern low-voltage microcontrollers and sensors.