Analog Devices Inc./Maxim Integrated MAX6865UK18D5S+T

Overview

The MAX6865UK18D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 1.8V reset threshold (±2.5%), 300ms minimum reset timeout (D5), and integrated watchdog timer with 3.3s typical timeout (S suffix). It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK18D5S+T datasheet, MAX6865UK18D5S+T pinout, MAX6865UK18D5S+T application, or MAX6865UK18D5S+T equivalent, key selection criteria include its 1.8V reset threshold accuracy, 300ms D5 timeout, S-suffix 3.3s watchdog period, push-pull active-high RESET output, and guaranteed reset validity down to VCC = +1.1V in portable low-voltage systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold hysteresis, a digital watchdog timer that clears on any WDI edge (min pulse width 150ns), and a fixed 300ms reset timeout after VCC recovery or MR deassertion. Its internal 10kΩ MR pullup and immunity to ≤40µs VCC transients at 100mV overdrive support robust operation in noisy battery-supplied environments.

The MAX6865UK18D5S+T belongs to the MAX6864–MAX6869 series with active-high push-pull RESET, manual reset input, and watchdog timer - distinct from MAX6861–MAX6863 (CT-selectable timeout) and MAX6854–MAX6856 (no watchdog). It requires no external components and operates across -40°C to +85°C.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), footprint-compatible with industry-standard 5-lead SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK18D5S+T and TPS3836K33DBVR, the MAX6865UK18D5S+T uniquely delivers 1.8V precision reset, 300ms timeout, and 3.3s watchdog in an active-high push-pull configuration - enabling direct interface to common µPs without logic inversion or external components.

Availability

MAX6865UK18D5S+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG recorders, and wireless patient alarms requiring stable component supply, long-term lifecycle support, and RoHS-compliant lead-free packaging.

Supply support for MAX6865UK18D5S+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 timing applications, with emphasis on low-power, high-reliability solutions for medical and portable electronics.

The MAX6864–MAX6869 product line delivers nanopower supervisory functions with integrated watchdog timers specifically for battery-critical medical, wearable, and IoT endpoints where reset integrity and ultra-low quiescent current are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK18D5S+T?

The MAX6865UK18D5S+T has a factory-trimmed reset threshold of 1.800V 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 "18" corresponds to 1.8V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for low-voltage brownout protection in 1.8V systems.

Does the MAX6865UK18D5S+T support active-high or active-low reset output?

The MAX6865UK18D5S+T provides an active-high push-pull RESET output (Pin 1), as confirmed in the MAX6864/MAX6865/MAX6866 Pin Description section and Selector Guide. Unlike the MAX6864 (active-low) or MAX6866 (open-drain), the MAX6865UK18D5S+T drives RESET high during fault conditions and requires no external pullup resistor - simplifying interface to µPs with active-high reset inputs.

What is the watchdog timeout period for the MAX6865UK18D5S+T?

The MAX6865UK18D5S+T features a watchdog timeout period of 3.3 seconds typical (S suffix), with min/max values of 1.5s/7.75s across temperature and voltage. This is explicitly defined in Table 3 (Watchdog Timeout) and confirmed by the "S" in the part number suffix. The watchdog clears on any rising or falling edge at WDI (Pin 4), with minimum detectable pulse width of 150ns.

How does the reset timeout period D5 translate to actual timing for the MAX6865UK18D5S+T?

The "D5" suffix in MAX6865UK18D5S+T specifies a minimum reset timeout period of 300ms, with typical and maximum values of 450ms and 600ms respectively (Table 4). This timeout begins after VCC rises above the 1.8V threshold or after MR is deasserted, ensuring the host µP remains held in reset long enough for full power stabilization and internal initialization - critical in battery-powered medical devices.

Is the MAX6865UK18D5S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK18D5S+T uses the standard 5-pin SOT23-5 package with Pin 1 = RESET (active-high), Pin 2 = GND, Pin 3 = MR, Pin 4 = WDI, Pin 5 = VCC - matching the MAX6864/MAX6866 pinout exactly. It is not pin-compatible with MAX6861–MAX6863 (CT pin instead of WDI) or MAX6854–MAX6856 (no WDI). Mechanical compatibility enables drop-in replacement only among MAX6864/MAX6865/MAX6866 variants.