Analog Devices Inc./Maxim Integrated MAX6865UK36D4S+T

Overview

MAX6865UK36D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.6V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP startup and fault recovery.

For engineers reviewing the MAX6865UK36D4S+T datasheet, MAX6865UK36D4S+T pinout, MAX6865UK36D4S+T application, or MAX6865UK36D4S+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-power systems requiring robust brownout protection.

Technical Context

The MAX6865UK36D4S+T integrates voltage monitoring, a manual reset input (MR), and a watchdog timer that triggers reset if WDI remains static beyond 3.3s (typ). Its internal reset timeout generator ensures 1200ms (min) assertion after VCC recovery or MR deassertion.

It uses BiCMOS process technology with 2848 transistors, supports VCC from 1.2V to 5.5V, and guarantees valid RESET output down to VCC = +1.1V. The device features 10kΩ internal MR pullup, 150ns WDI pulse width detection, and operates across –40°C to +85°C.

Key Specifications

Pinout & Package

MAX6865UK36D4S+T is housed in a lead-free 5-pin SOT23-5 package (2.9mm × 1.6mm × 1.1mm), optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK36D4S+T and TPS3836K33DBVR, MAX6865UK36D4S+T uniquely delivers active-high RESET, 1200ms timeout, and integrated watchdog - making it optimal for modern low-power µPs requiring both robust startup and runtime fault resilience.

Availability

MAX6865UK36D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, smart wearables, and industrial handheld terminals requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK36D4S+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications markets.

MAX6865UK36D4S+T belongs to the MAX6854–MAX6869 nanopower supervisory family, designed specifically for ultra-low-power battery-operated medical and portable electronics requiring guaranteed reset behavior under brownout and firmware fault conditions.

FAQ

What is the reset threshold voltage of MAX6865UK36D4S+T?

The MAX6865UK36D4S+T has a factory-trimmed reset threshold of 3.600V with ±2.5% tolerance over –40°C to +85°C. This value corresponds to the "36" suffix in the part number and is verified per Table 2 (Threshold Suffix Guide) in the datasheet. The threshold is referenced to VCC and remains stable across temperature, enabling precise supervision of 3.3V rails with adequate margin.

Does MAX6865UK36D4S+T include a watchdog timer?

Yes, MAX6865UK36D4S+T includes a watchdog timer with a typical timeout period of 3.3 seconds (S-suffix), as confirmed in Table 3 (Watchdog Timeout) and the Selector Guide. The WDI pin (Pin 4) must be toggled within this window to prevent reset assertion; static high or low states longer than 3.3s trigger a full reset cycle with 1200ms timeout.

What is the function of Pin 1 on MAX6865UK36D4S+T?

Pin 1 of MAX6865UK36D4S+T is the RESET output, configured as an active-high push-pull driver. When asserted, it drives high to signal reset to the microprocessor; it deasserts low upon timeout completion. Unlike open-drain variants, it requires no external pullup resistor and interfaces directly with µP reset pins rated for VCC-referenced logic levels.

What is the minimum supply voltage at which MAX6865UK36D4S+T guarantees valid reset operation?

MAX6865UK36D4S+T guarantees valid reset output down to VCC = +1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, RESET behavior is not characterized - but above 1.1V, the device ensures deterministic assertion/deassertion timing and logic levels regardless of VCC droop during brownout events.

How does the manual reset (MR) input behave on MAX6865UK36D4S+T?

The MR input (Pin 3) is active-low with an internal 10kΩ pullup to VCC. Driving MR low initiates immediate reset assertion, which persists for the full 1200ms timeout after MR returns high. Glitch rejection is 200ns, and minimum pulse width is 1µs. If unused, MR may be left floating or tied to VCC - no external components are needed for basic operation.