Analog Devices Inc./Maxim Integrated MAX6865UK40D5S+T

Overview

The MAX6865UK40D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, integrating voltage monitoring (4.000V reset threshold), manual reset input (MR), and watchdog timer (3.3s typical timeout). It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. It serves as a system-level power-on reset and fault recovery controller in ultra-low-power portable medical and consumer devices.

For engineers reviewing the MAX6865UK40D5S+T datasheet, MAX6865UK40D5S+T pinout, MAX6865UK40D5S+T application, or MAX6865UK40D5S+T equivalent, this page delivers verified electrical parameters, functional pin mapping, real-world use cases for battery-powered equipment, and validated alternative parts with documented technical differences.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, combined 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 robust manual reset without external components.

The active-high push-pull RESET output drives high to VCC with VOH ≥ 0.8×VCC at ISOURCE = 500µA, while sinking capability is not specified - confirming its unidirectional high-drive architecture. Reset timeout is fixed at 300ms (min), determined by internal RC timing and factory-trimmed for stability across temperature.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK40D5S+T and TPS3836K33DBVR, the MAX6865UK40D5S+T uniquely combines 4.000V precision monitoring, 3.3s watchdog, 300ms reset timeout, and active-high push-pull output - enabling simpler, lower-power, and more robust reset control in portable medical and IoT endpoints.

Availability

MAX6865UK40D5S+T is available at Aetrix Electronics and suitable for portable medical devices, wearable electronics, industrial handheld terminals, and low-power IoT sensors requiring stable component supply and long-term lifecycle support.

Supply support for MAX6865UK40D5S+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 management, sensing, and interface applications in demanding industrial, medical, and communications systems.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting battery-critical applications where reliability, ultra-low ICC, and integrated watchdog capability are mandatory - especially in portable healthcare and compact consumer electronics.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D5S+T?

The MAX6865UK40D5S+T has a factory-trimmed reset threshold of 4.000V, with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "40" corresponds to 4.000V nominal. The device asserts reset when VCC falls below this threshold and maintains reset for 300ms after VCC recovers.

Does the MAX6865UK40D5S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK40D5S+T includes a watchdog timer with a typical timeout of 3.3s, indicated by the "S" suffix in the part number. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period, triggering a full reset cycle. This is distinct from the D5 reset timeout (300ms), which governs reset deassertion duration.

What type of reset output does the MAX6865UK40D5S+T provide?

The MAX6865UK40D5S+T provides an active-high push-pull RESET output (Pin 1), as confirmed in the MAX6865-specific pin description on page 8 of the datasheet. Unlike open-drain variants, it drives high to VCC without requiring an external pullup resistor, simplifying interface to microcontrollers expecting active-high reset signals.

What is the minimum supply voltage at which the MAX6865UK40D5S+T guarantees valid reset operation?

The MAX6865UK40D5S+T guarantees valid reset assertion down to VCC = +1.1V, as explicitly stated in the Features list and Electrical Characteristics table. This ensures fail-safe behavior deeper into power collapse than many competing supervisors, critical for maintaining system integrity in battery-powered applications nearing end-of-life.

How does the manual reset (MR) input function on the MAX6865UK40D5S+T?

The MR input on the MAX6865UK40D5S+T is active-low with an internal 10kΩ pullup to VCC. Driving MR low initiates a reset that persists for the full 300ms timeout period even after MR returns high. It accepts CMOS logic levels, rejects glitches <200ns, and requires only a 1µs minimum pulse width - enabling direct connection to momentary switches or digital outputs without debounce circuitry.