Analog Devices Inc./Maxim Integrated MAX6865UK19D5S+T

Overview

The MAX6865UK19D5S+T 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 1.9V reset threshold (suffix '19'), 300ms minimum reset timeout (suffix 'D5'), and integrated watchdog timer with 3.3s typical timeout (suffix 'S'). It monitors VCC, responds to manual reset (MR), and asserts reset on voltage drop, MR assertion, or watchdog expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK19D5S+T datasheet, MAX6865UK19D5S+T pinout, MAX6865UK19D5S+T application, or MAX6865UK19D5S+T equivalent, key selection criteria include its 1.9V reset threshold accuracy, 300ms reset timeout stability over temperature, watchdog immunity to short transients, and guaranteed reset validity down to VCC = +1.1V - all critical for low-power embedded safety-critical systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold tolerance 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). The internal reset timeout generator uses RC-based timing with <±10% variation across temperature and supply.

It integrates a 10kΩ internal MR pullup, supports push-pull active-high RESET output (per MAX6865 variant), and features glitch rejection on MR (200ns) and VCC transient immunity - enabling reliable operation in noisy, low-voltage battery systems without external components.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint-compatible with industry-standard 5-pin supervisory ICs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK19D5S+T, the MAX6865UK19D5S+T offers direct compatibility with active-high reset µPs - eliminating external inverters - while matching all supervision timing and power metrics. Against TPS3836K33DBVR, it delivers 7× lower ICC and adds essential watchdog fault coverage for medical firmware validation.

Availability

MAX6865UK19D5S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, smart hearing aids, and wearable drug delivery pumps requiring stable component supply across long-life medical product lifecycles.

Supply support for MAX6865UK19D5S+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 small form factor.

The MAX6854–MAX6869 family was engineered specifically for nanopower battery-operated systems needing simultaneous voltage monitoring, manual reset, and watchdog protection - consolidating three functions into a single 5-pin SOT23 device.

FAQ

What is the exact reset threshold voltage of the MAX6865UK19D5S+T?

The MAX6865UK19D5S+T has a factory-trimmed reset threshold of 1.9V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the official datasheet, where suffix '19' corresponds to VTH = 1.900V (typ). The MAX6865UK19D5S+T maintains this accuracy without external calibration.

Does the MAX6865UK19D5S+T support active-high or active-low reset output?

The MAX6865UK19D5S+T provides an active-high push-pull RESET output, as defined by its MAX6865 variant designation. Pin 1 drives high during reset assertion and low when deasserted - directly compatible with microprocessors requiring an active-high reset signal. This differs from MAX6864 (active-low) and MAX6866 (open-drain) variants in the same family.

What is the watchdog timeout behavior of the MAX6865UK19D5S+T?

The MAX6865UK19D5S+T features a watchdog timer with a typical timeout of 3.3s (suffix 'S'), with min/max values of 1.5s and 7.75s. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond the timeout period - triggering a full reset cycle with the configured 300ms (D5) timeout. This behavior is documented in Table 3 and Figure 3 of the datasheet.

Can the MAX6865UK19D5S+T operate reliably below 1.8V supply?

Yes - the MAX6865UK19D5S+T is fully specified down to VCC = +1.1V, with guaranteed reset assertion validity and functional timing. Its 170nA supply current and 1.9V threshold make it uniquely suited for LiMnO₂ and zinc-air batteries whose voltage decays below 1.8V during end-of-life. Electrical Characteristics table confirms operation from 1.2V (min) to 5.5V (max).

Is an external pullup resistor required for the RESET output of the MAX6865UK19D5S+T?

No - the MAX6865UK19D5S+T uses a push-pull active-high RESET output (Pin 1), which actively drives both high and low states. Unlike open-drain variants, it requires no external pullup resistor. This simplifies design, reduces component count, and ensures fast, rail-to-rail reset transitions without rise-time limitations imposed by RC networks.