Analog Devices Inc./Maxim Integrated MAX6865UK18D1S+T

Overview

The MAX6865UK18D1S+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 1.8V reset threshold (±2.5%), and a 10ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and watchdog timer functionality with 3.3s typical watchdog timeout (S-suffix), and asserts an active-high push-pull RESET output. It is designed for reliable power-up/power-down supervision in battery-critical portable medical and consumer electronics.

For engineers reviewing the MAX6865UK18D1S+T datasheet, MAX6865UK18D1S+T pinout, MAX6865UK18D1S+T application, or MAX6865UK18D1S+T equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative options - all grounded in Maxim's official specifications for the precise part number.

Technical Context

The MAX6865UK18D1S+T implements a precision bandgap-based voltage monitor with guaranteed reset validity down to VCC = +1.1V and immunity to short VCC transients (e.g., ≤40µs at 100mV overdrive). Its internal watchdog timer clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ), triggering a full reset timeout cycle.

This device uses BiCMOS process technology (2848 transistors) and features an internally pulled-up MR input (10kΩ), a dedicated WDI input tolerant to 0.3×VCC/0.7×VCC logic thresholds, and push-pull RESET output referenced to VCC with VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA).

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), 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 MAX6864UK18D1S+T, the MAX6865UK18D1S+T avoids level-shifting overhead via native active-high RESET; versus TPS3836K33DBVR, it delivers 10,000× lower ICC and integrated watchdog - critical for portable medical compliance.

Availability

MAX6865UK18D1S+T is available at Aetrix Electronics and suitable for portable glucose monitors, low-power patient monitors, MP3 player firmware recovery, and PDA power management requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK18D1S+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, with emphasis on reliability and low-power innovation.

The MAX6854–MAX6869 family delivers nanopower supervisory solutions specifically for battery-constrained portable electronics, combining voltage monitoring, manual reset, and watchdog in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6865UK18D1S+T?

The MAX6865UK18D1S+T has a factory-trimmed reset threshold of 1.800V with ±2.5% tolerance over -40°C to +85°C, as defined by the '18' suffix in its part number per Maxim's Threshold Suffix Guide (Table 2). This value is laser-trimmed during production and does not require external calibration. The MAX6865UK18D1S+T maintains this accuracy across its full operating temperature range and supply voltage (1.2V–5.5V).

Does the MAX6865UK18D1S+T require external components for basic operation?

No, the MAX6865UK18D1S+T operates autonomously with zero external components for core supervision: it includes an internal 10kΩ pullup on MR, no timing capacitor for reset timeout (D1 = 10ms fixed), and no resistor network for threshold setting (1.8V factory-trimmed). Only a 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity - a standard practice, not a functional requirement.

How does the watchdog timer in the MAX6865UK18D1S+T respond to software stalls?

The MAX6865UK18D1S+T watchdog timer expires if the WDI input remains static (high or low) for longer than 3.3s (typ), triggering a full 10ms reset pulse. The timer clears on every rising or falling edge at WDI - enabling robust detection of firmware hangs, even during tight polling loops. Unlike windowed watchdogs, it requires no precise timing discipline, making it ideal for interrupt-driven or event-based firmware architectures.

What is the function of Pin 1 (RESET) on the MAX6865UK18D1S+T?

Pin 1 of the MAX6865UK18D1S+T is the active-high push-pull RESET output. It drives high (≥0.8×VCC) when asserting reset and low (≤0.3V) when deasserted, eliminating need for external pullups. This output directly interfaces with µPs requiring active-high reset inputs - such as many ARM Cortex-M series - and guarantees valid logic levels across the full 1.2V–5.5V VCC range.

Can the MAX6865UK18D1S+T supervise a 1.2V supply rail?

No - the MAX6865UK18D1S+T is specified for operation with VCC from 1.2V to 5.5V, but its 1.8V reset threshold means it cannot reliably monitor a 1.2V rail. Attempting to do so would result in permanent reset assertion, as VCC never reaches the 1.8V trip point. For 1.2V supervision, a different variant (e.g., MAX6865UK12D1S+T, if offered) or alternate family member with lower threshold suffix must be selected.