Analog Devices Inc./Maxim Integrated MAX6866UK41D3S

Overview

The MAX6866UK41D3S from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functions. It asserts an active-low open-drain RESET output when VCC drops below 4.100V (typ), MR is pulled low, or the watchdog expires after 3.3s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) supply current and guarantees valid reset operation down to VCC = +1.1V.

For engineers reviewing the MAX6866UK41D3S datasheet, MAX6866UK41D3S pinout, MAX6866UK41D3S application, or MAX6866UK41D3S equivalent, key selection criteria include its factory-trimmed 4.100V reset threshold, 300ms (min) reset timeout period, 3.3s watchdog timeout, open-drain RESET output, and compatibility with battery-powered medical and portable electronics requiring robust brownout and code-execution error protection.

Technical Context

The MAX6866UK41D3S implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature, coupled with a digital watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable direct switch interfacing without external components.

This device belongs to the MAX6864–MAX6869 variant group featuring both MR and WDI inputs, fixed D3 (150–300ms) reset timeout, and S-suffix (3.3s typ) watchdog. Unlike CT-selectable or push-pull variants, MAX6866UK41D3S provides open-drain RESET output only - confirmed by Selector Guide and Pin Description tables.

Key Specifications

Pinout & Package

MAX6866UK41D3S is housed in a 5-pin SOT23-5 package (JEDEC MO-178AA), with pins arranged as follows (top view): Pin 1 = RESET, Pin 2 = GND, Pin 3 = MR, Pin 4 = WDI, Pin 5 = VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK41D3S and TPS3838K33DBVR, MAX6866UK41D3S uniquely delivers open-drain flexibility, 4.1V precision thresholding, and nanopower operation - making it the sole option for battery-constrained 4.1V systems requiring both watchdog and bus-compatible reset signaling.

Availability

MAX6866UK41D3S is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and wearable health trackers requiring stable component supply across extended production lifecycles.

Supply support for MAX6866UK41D3S 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 demanding industrial, medical, and communications applications.

The MAX6864–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in space- and energy-constrained portable electronics, integrating voltage monitoring, manual reset, and watchdog functions into a single 5-pin SOT23 package.

FAQ

What is the exact reset threshold voltage of the MAX6866UK41D3S?

The MAX6866UK41D3S has a factory-trimmed reset threshold voltage of 4.100V (typical), with guaranteed tolerance of ±2.5% over the full -40°C to +85°C temperature range. This value corresponds to the "41" suffix in the part number per Table 2 (Threshold Suffix Guide), and is confirmed in the Electrical Characteristics table under VTH parameter.

Does the MAX6866UK41D3S include a watchdog timer, and what is its timeout period?

Yes, the MAX6866UK41D3S includes a watchdog timer with a typical timeout period of 3.3s, indicated by the "S" suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, which specifies S = 1.5s/3.3s/7.75s (min/typ/max). The timer clears on any WDI edge and expires only if WDI remains static beyond this interval.

What type of RESET output does the MAX6866UK41D3S provide, and how is it configured?

The MAX6866UK41D3S provides an active-low open-drain RESET output (Pin 1), as confirmed in the Selector Guide and MAX6864/MAX6866 Pin Description. It requires an external pullup resistor to the target logic supply and supports level-shifting across 0–5.5V. This configuration enables wired-OR reset buses and interoperability with diverse voltage domains - unlike push-pull variants in the same family.

What is the minimum reset timeout period for the MAX6866UK41D3S, and how is it selected?

The MAX6866UK41D3S has a fixed minimum reset timeout period of 150ms, corresponding to the "D3" suffix per Table 4 (Reset Timeout Periods). This value is factory-set and non-adjustable - unlike CT-selectable variants (e.g., MAX6861–MAX6863). The actual timeout ranges from 150ms (min) to 300ms (typ) depending on process and temperature.

Is the MAX6866UK41D3S compatible with 1.8V or 2.5V supply rails?

Yes, the MAX6866UK41D3S operates across VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V, as specified in Absolute Maximum Ratings and Electrical Characteristics. Its 4.100V threshold applies to the monitored VCC rail - meaning it is intended for systems where the primary supply is ~4.1V (e.g., Li-ion with protection circuit), while internal logic functions correctly at lower voltages during brownout.