Analog Devices Inc./Maxim Integrated MAX6865UK40D6S+T

Overview

The MAX6865UK40D6S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (4.000V reset threshold), manual reset input, and watchdog timer with 209s typical timeout. It asserts an active-high push-pull RESET output when VCC drops below threshold, MR is asserted, or watchdog expires - designed for ultra-low-power portable systems requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6865UK40D6S+T datasheet, MAX6865UK40D6S+T pinout, MAX6865UK40D6S+T application, or MAX6865UK40D6S+T equivalent, key selection criteria include its 170nA typical supply current, factory-trimmed 4.000V threshold, 1200ms minimum reset timeout (D6), S-suffix 3.3s/209s watchdog option, and compatibility with battery-backed medical and handheld devices operating across –40°C to +85°C.

Technical Context

This device 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 209s (typ). The internal reset timeout generator ensures minimum 600ms assertion after VCC recovery or MR release.

It features a dedicated MR input with 10kΩ internal pullup, glitch rejection of 200ns, and MR-to-reset delay of 250ns. The active-high push-pull RESET output guarantees VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V) and VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V), supporting direct interface to µP reset inputs without external components.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), 2.9mm × 1.6mm footprint, 1.1mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK40D6S+T, the MAX6865UK40D6S+T offers active-high RESET for direct compatibility with common µP reset pins, while TPS3838K33DBVR trades watchdog capability and nanopower operation for lower cost in simple voltage-monitoring roles - making MAX6865UK40D6S+T optimal for battery-critical, software-supervised portable medical devices.

Availability

MAX6865UK40D6S+T is available at Aetrix Electronics and suitable for portable glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart energy meters requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK40D6S+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, sensing, and interface applications in industrial, medical, and communications markets.

The MAX68xx family delivers nanopower supervisory circuits optimized for battery-operated portable equipment where ultra-low ICC, guaranteed reset validity at low VCC, and integrated watchdog supervision are essential for safety-critical firmware reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D6S+T?

The MAX6865UK40D6S+T has a factory-trimmed reset threshold of 4.000V, with ±2.5% tolerance 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 "40" corresponds to 4.000V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, independent of threshold accuracy drift.

Does the MAX6865UK40D6S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK40D6S+T includes a watchdog timer with S-suffix configuration, providing a typical timeout of 209s (minimum 95s, maximum 487s). The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period - enabling long-interval software supervision ideal for low-duty-cycle portable medical firmware.

What type of reset output does the MAX6865UK40D6S+T provide, and how is it interfaced?

The MAX6865UK40D6S+T provides an active-high push-pull RESET output (Pin 1), eliminating the need for an external pullup resistor. It sources up to 500µA at VOH ≥ 0.8×VCC (VCC ≥ 2.38V) and sinks up to 1.2mA at VOL ≤ 0.3V (VCC ≥ 2.38V), allowing direct connection to standard µP reset inputs without level-shifting or additional components.

What is the reset timeout period for the MAX6865UK40D6S+T, and how is it selected?

The MAX6865UK40D6S+T uses the D6 reset timeout option, delivering a minimum reset assertion period of 600ms (typical 900ms, maximum 1200ms) after VCC rises above threshold or MR is deasserted. This fixed timeout is factory-set and cannot be modified externally - ensuring predictable µP initialization timing across all operating conditions.

Is the MAX6865UK40D6S+T compatible with lead-free PCB assembly processes?

Yes, the MAX6865UK40D6S+T is supplied in lead-free (RoHS-compliant) packaging, as indicated by the "+T" suffix. It is qualified for standard Pb-free reflow profiles per JEDEC J-STD-020, with a maximum peak temperature of +260°C and 10-second duration at soldering temperature - fully compatible with modern automated SMT assembly lines.