Analog Devices Inc./Maxim Integrated MAX6866UK43D3S+

Overview

The MAX6866UK43D3S+ from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.300V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts an active-low open-drain RESET output - ideal for battery-powered glucose monitors and portable medical devices requiring reliable brownout protection.

For engineers reviewing the MAX6866UK43D3S+ datasheet, MAX6866UK43D3S+ pinout, MAX6866UK43D3S+ application, or MAX6866UK43D3S+ equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options - all grounded in Maxim's official electrical characteristics and functional diagrams.

Technical Context

The MAX6866UK43D3S+ integrates three core functions: precision voltage monitoring (VTH = 4.300V ±2.5% over -40°C to +85°C), a manual reset input (MR) with 250ns delay and internal 10kΩ pullup, and a watchdog timer (WDI) that triggers reset if no edge occurs within 3.3s (typ). Its open-drain RESET output remains asserted for ≥300ms after VCC rises above threshold or MR deasserts.

It operates across VCC = 1.2V–5.5V, guarantees valid reset down to VCC = 1.1V, and exhibits immunity to VCC transients ≤40µs at 100mV overdrive. The device uses BiCMOS process (2848 transistors) and requires no external components beyond standard 0.1µF VCC bypass.

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 MAX6866UK43D3S+, MAX6864UK43D3S+ offers identical supervision timing but different output drive architecture, while TPS3839G33DBVR reduces cost and complexity at the expense of watchdog capability and ultra-low current performance.

Availability

MAX6866UK43D3S+ is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and smart wearable health trackers requiring stable component supply across long product lifecycles.

Supply support for MAX6866UK43D3S+ 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 high-performance analog and mixed-signal ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality specifically for battery-constrained portable medical and IoT endpoints where sub-µA quiescent current and guaranteed reset validity down to 1.1V are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6866UK43D3S+?

The MAX6866UK43D3S+ has a factory-trimmed reset threshold of 4.300V, with guaranteed tolerance of ±2.5% over the full -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "43" corresponds to 4.300V nominal. The MAX6866UK43D3S+ maintains this accuracy without external calibration or trimming components.

Does the MAX6866UK43D3S+ include a watchdog timer, and what is its timeout?

Yes, the MAX6866UK43D3S+ includes an integrated watchdog timer with a typical timeout of 3.3 seconds, indicated by the "S" suffix in the part number. The timer resets on any rising or falling edge at the WDI pin and triggers a reset if no transition occurs within the timeout window. This behavior is explicitly defined in Table 3 (Watchdog Timeout) and applies only to MAX6864–MAX6869 variants like the MAX6866UK43D3S+.

What type of RESET output does the MAX6866UK43D3S+ provide?

The MAX6866UK43D3S+ provides an active-low open-drain RESET output on Pin 1. This configuration requires an external pullup resistor to the target logic rail (e.g., 1.8V, 3.3V, or 5V), enabling level-shifting across voltage domains. The open-drain structure is confirmed in the MAX6864/MAX6866 Pin Description section and distinguishes it from push-pull variants like MAX6864UK43D3S+.

What is the minimum reset timeout period for the MAX6866UK43D3S+?

The MAX6866UK43D3S+ has a minimum reset timeout period of 300ms, specified by the "D3" suffix in the part number per Table 4 (Reset Timeout Periods). This duration ensures sufficient hold time for microprocessors to complete power-up initialization sequences, especially in systems with slow clock startups or complex peripheral handshaking. The 300ms value is guaranteed minimum, with typical and maximum values of 225ms and 300ms respectively.

Is the MAX6866UK43D3S+ compatible with 1.2V supply operation?

Yes, the MAX6866UK43D3S+ operates across VCC = 1.2V to 5.5V and guarantees valid reset assertion down to VCC = 1.1V. At 1.2V, its supply current remains ultra-low (190nA typ), and all key functions - voltage monitoring, MR response, and WDI edge detection - remain fully operational. This capability is documented in the Absolute Maximum Ratings and Electrical Characteristics tables, making it suitable for emerging ultra-low-voltage embedded systems.