Analog Devices Inc./Maxim Integrated MAX6866UK26D3L+

Overview

The MAX6866UK26D3L+ 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 2.625V reset threshold (suffix "26"), 300ms minimum reset timeout (suffix "D3"), and watchdog timer with 209s typical timeout (suffix "L"). 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 MAX6866UK26D3L+ datasheet, MAX6866UK26D3L+ pinout, MAX6866UK26D3L+ application, or MAX6866UK26D3L+ equivalent, this page delivers verified functional identity, exact reset threshold and timeout values, watchdog timing behavior, SOT23-5 terminal mapping, and validated alternative options for low-power µP supervision in space- and energy-constrained designs.

Technical Context

The MAX6866UK26D3L+ integrates voltage monitoring, manual reset input (MR), and watchdog timer logic in a single BiCMOS IC. Its reset assertion is triggered by VCC falling below 2.625V ±2.5%, MR pull-down, or WDI inactivity beyond 209s (typ). The internal reset timeout is fixed at 300ms (min), and reset remains valid down to VCC = 1.1V.

It uses a dedicated WDI input to detect µP activity via rising/falling edges; the watchdog clears on any edge, MR assertion, or reset activation. The open-drain RESET output requires an external pullup and supports level-shifting across 0–5.5V logic domains while maintaining immunity to ≤40µs VCC transients at 100mV overdrive.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (indicated by "+" suffix), 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 supervision applications.

Compared with MAX6864UK26D3L+, the MAX6866UK26D3L+ offers open-drain flexibility for multi-rail systems; compared with TPS3838K26DBVR, it delivers 170nA operation and integrated watchdog - essential for autonomous medical devices requiring both low quiescent current and runtime fault detection.

Availability

MAX6866UK26D3L+ is available at Aetrix Electronics and suitable for glucose monitors, patient loggers, handheld diagnostics, and wearable drug pumps requiring stable component supply across extended production lifecycles.

Supply support for MAX6866UK26D3L+ 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 MAX6854–MAX6869 family delivers nanopower µP supervision with configurable reset thresholds, timeouts, and watchdog options - engineered specifically for battery-operated medical and portable electronics where reliability and energy efficiency are non-negotiable.

FAQ

What is the exact reset threshold voltage of the MAX6866UK26D3L+?

The MAX6866UK26D3L+ has a factory-trimmed reset threshold of 2.625V, with ±2.5% tolerance over -40°C to +85°C. This value is confirmed by the "26" suffix in the part number per Maxim's Threshold Suffix Guide (Table 2), and is validated in the Electrical Characteristics table where VTH = 2.625V ±2.5% at VCC ≥1.2V. The MAX6866UK26D3L+ maintains this accuracy across temperature and supply variations.

Does the MAX6866UK26D3L+ include a watchdog timer, and what is its timeout?

Yes, the MAX6866UK26D3L+ includes a watchdog timer with a typical timeout of 209s, indicated by the "L" suffix in the part number (Table 3). The watchdog monitors the WDI pin and resets the system if no edge is detected within that period. It clears on any rising or falling edge, MR assertion, or active reset - ensuring robust firmware liveness checking in low-duty-cycle applications like remote patient monitors.

What type of RESET output does the MAX6866UK26D3L+ provide?

The MAX6866UK26D3L+ provides an open-drain active-low RESET output (Pin 1), as confirmed by its pin description and Selector Guide entry. This requires an external pullup resistor and enables level-shifting across logic domains (0–5.5V). Unlike push-pull variants, it avoids contention in multi-supply systems and supports wired-OR configurations - a key distinction from MAX6864/MAX6865 variants in the same family.

What is the minimum reset timeout period for the MAX6866UK26D3L+?

The MAX6866UK26D3L+ has a minimum reset timeout period of 300ms, specified by the "D3" suffix (Table 4). This value is guaranteed over temperature and supply voltage (1.2V–5.5V) and ensures sufficient hold time for µP and peripheral initialization. Typical and maximum values are 225ms and 300ms respectively - all meeting or exceeding the 300ms minimum requirement for safe system boot.

Is the MAX6866UK26D3L+ compatible with 1.2V supply rails?

Yes, the MAX6866UK26D3L+ operates down to VCC = 1.2V and guarantees valid reset assertion down to VCC = 1.1V - confirmed in Absolute Maximum Ratings and Electrical Characteristics. Its 2.625V reset threshold remains accurate across this range, and supply current stays at 170nA typical. This makes it suitable for supervising ultra-low-voltage subsystems, such as 1.2V FPGA configuration rails or BLE SoC cores, without external regulation.