Analog Devices Inc./Maxim Integrated MAX6865UK18D4S+T

Overview

The MAX6865UK18D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (1.755V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 1200ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK18D4S+T datasheet, MAX6865UK18D4S+T pinout, MAX6865UK18D4S+T application, or MAX6865UK18D4S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset output type, and compatibility with low-voltage µP systems requiring long battery life and robust fault recovery.

Technical Context

The MAX6865UK18D4S+T implements a dual-trigger reset architecture: one path responds to VCC falling below 1.755V ±2.5%, and another activates when the WDI input remains static beyond the 209s (typ) watchdog timeout. Its internal 10kΩ MR pullup and glitch rejection (200ns) enable direct switch interfacing without external components.

Reset assertion is latched and held for a fixed 1200ms minimum timeout after VCC rises above threshold and MR deasserts - independent of watchdog state. The active-high push-pull RESET output is referenced to VCC and guarantees VOH ≥ 0.8×VCC at ISOURCE = 500µA, supporting direct connection to µP reset inputs across 1.2V–5.5V supply range.

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 MAX6864UK18D4S+T and TPS3836K33DBVR, the MAX6865UK18D4S+T uniquely delivers long-interval (209s) watchdog supervision with 1.755V precision threshold and 1200ms reset hold time - essential for safety-critical, low-duty-cycle medical and industrial edge nodes.

Availability

MAX6865UK18D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, smart wearables, and industrial sensor nodes requiring stable component supply and long-term lifecycle support.

Supply support for MAX6865UK18D4S+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 MAX6865UK18D4S+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power, safety-aware embedded systems where battery longevity and deterministic fault recovery are mandatory.

FAQ

What is the reset threshold voltage of the MAX6865UK18D4S+T?

The MAX6865UK18D4S+T has a factory-trimmed reset threshold of 1.755V ±2.5%, corresponding to the '18' suffix in its part number. This value is guaranteed over the full -40°C to +85°C operating temperature range and ensures reliable brownout detection for 1.8V nominal supply rails. The MAX6865UK18D4S+T uses this threshold to assert RESET whenever VCC falls below this level.

Does the MAX6865UK18D4S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK18D4S+T includes a watchdog timer with an L-suffix configuration, providing a typical timeout period of 209 seconds. This long interval is designed for firmware that performs infrequent operations or extended sleep cycles. The watchdog timer clears on any rising or falling edge at the WDI pin and triggers reset if no transition occurs within the timeout window. The MAX6865UK18D4S+T relies on this feature to recover from software hangs in low-duty-cycle applications.

What type of reset output does the MAX6865UK18D4S+T provide, and how is it configured?

The MAX6865UK18D4S+T provides an active-high push-pull RESET output on Pin 1, eliminating the need for an external pullup resistor. This output is referenced to VCC and guarantees VOH ≥ 0.8×VCC when sourcing 500µA, ensuring compatibility with standard µP reset inputs across its 1.2V–5.5V operating range. Unlike open-drain variants, the MAX6865UK18D4S+T's push-pull architecture delivers fast, low-impedance reset assertion and release without external components.

How does the MAX6865UK18D4S+T handle short VCC transients, and what is its immunity specification?

The MAX6865UK18D4S+T is designed to ignore short-duration VCC transients that could cause spurious resets. It exhibits immunity to glitches ≤40µs wide when the overdrive is 100mV above the 1.755V threshold - verified by the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" curve in its datasheet. This robustness allows reliable operation in electrically noisy environments such as portable medical devices with switching regulators. The MAX6865UK18D4S+T maintains reset stability without requiring additional filtering.

What is the supply current of the MAX6865UK18D4S+T, and how does it impact battery life?

The MAX6865UK18D4S+T draws only 170nA typical supply current at VCC = 1.8V and +25°C, with maximum ICC under 400nA across temperature and voltage. This nanopower consumption enables multi-year operation on standard coin cells - for example, exceeding 10 years on a 220mAh CR2032 when paired with a µP in deep-sleep mode. The MAX6865UK18D4S+T achieves this efficiency without sacrificing reset accuracy or watchdog functionality, making it ideal for maintenance-free wearable and implantable systems.