Analog Devices Inc./Maxim Integrated MAX6865UK25D2S+T

Overview

The MAX6865UK25D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (2.500V reset threshold), manual reset input (MR), and watchdog timer (3.3s timeout) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK25D2S+T datasheet, MAX6865UK25D2S+T pinout, MAX6865UK25D2S+T application, or MAX6865UK25D2S+T equivalent, key selection criteria include its 2.5V factory-trimmed threshold, 40ms reset timeout, 3.3s watchdog period, guaranteed reset validity down to VCC = +1.1V, and compatibility with noisy low-power systems requiring glitch immunity and no external components.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, 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 250ns MR-to-reset delay enable robust manual reset triggering without external circuitry.

The push-pull active-high RESET output drives directly to VCC with VOH ≥ 0.8×VCC at 500µA source current, eliminating need for external pullups. Immunity to VCC transients ≤40µs (at 100mV overdrive) ensures reliable operation in electrically noisy portable environments.

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 MAX6864UK25D2S+T, the MAX6865UK25D2S+T provides active-high RESET for direct µP interface without level-shifting, while TPS3836K25DBVR trades off watchdog capability and ultra-low power for lower cost in non-critical applications.

Availability

MAX6865UK25D2S+T is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld scanners, low-power IoT edge sensors, and battery-backed data loggers requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK25D2S+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 demanding industrial, medical, and communications applications, emphasizing low power, high reliability, and integration.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting battery-constrained systems where long service life, deterministic reset behavior, and watchdog safety are critical - especially in portable healthcare and ruggedized field equipment.

FAQ

What is the exact reset threshold voltage of the MAX6865UK25D2S+T?

The MAX6865UK25D2S+T has a factory-trimmed reset threshold of 2.500V 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 "25" corresponds to 2.500V nominal. The MAX6865UK25D2S+T maintains this precision without external calibration or trimming components.

Does the MAX6865UK25D2S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK25D2S+T includes a watchdog timer with a typical timeout period of 3.3 seconds, denoted by the "S" suffix in its 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 sequence. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section.

What type of RESET output does the MAX6865UK25D2S+T provide, and how is it configured?

The MAX6865UK25D2S+T provides an active-high push-pull RESET output, as confirmed by its pin description (Pin 1 = RESET, active-high) and Selector Guide. It drives high during reset assertion and low otherwise, referenced directly to VCC, eliminating need for external pullup resistors. This configuration is fixed per the part number and cannot be altered externally.

What is the minimum reset timeout period for the MAX6865UK25D2S+T, and how is it selected?

The MAX6865UK25D2S+T has a fixed minimum reset timeout period of 40ms, indicated by the "D2" suffix in its part number per Table 4 (Reset Timeout Periods). Unlike variants with CT pins, this timeout is factory-programmed and not user-selectable. The device guarantees reset assertion for ≥40ms after VCC exceeds the threshold and MR deasserts.

Is the MAX6865UK25D2S+T compatible with 1.8V systems, and what is its lowest valid VCC for reset operation?

Yes, the MAX6865UK25D2S+T operates from VCC = 1.2V to 5.5V and guarantees valid reset assertion down to VCC = +1.1V, as specified in the Electrical Characteristics table. At 1.8V supply, its 170nA typical supply current and 2.5V threshold remain fully functional, making it suitable for mixed-voltage systems where the supervisor monitors a higher rail than the MCU core voltage.