Analog Devices Inc./Maxim Integrated MAX6865UK27D4L+T

Overview

The MAX6865UK27D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (2.700V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, maintaining reset for 1200ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK27D4L+T datasheet, MAX6865UK27D4L+T pinout, MAX6865UK27D4L+T application, or MAX6865UK27D4L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), fixed 1200ms reset timeout, and 209s watchdog period - all critical for low-power embedded systems requiring deterministic fault recovery.

Technical Context

This device integrates a precision bandgap-based voltage monitor with ±2.5% threshold accuracy, a digital watchdog timer that clears on any WDI edge (rising or falling), and a monolithic reset timeout generator with no external components required. Its BiCMOS process enables ultra-low ICC (170nA typ at 2.5V) while maintaining robust noise immunity via internal 10kΩ MR pullup and 200ns MR glitch rejection.

The MAX6865UK27D4L+T implements a three-event reset trigger: VCC falling below 2.700V, MR pulled low, or WDI remaining static beyond 209s (typ). Reset deassertion follows a fixed 1200ms (D4 option) timeout after VCC exceeds threshold *and* MR deasserts - not synchronized to WDI activity, ensuring deterministic recovery timing independent of software behavior.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK27D4L+T, MAX6864UK27D4L+T removes MR functionality to reduce complexity, while TPS3838K27DBVR trades 20× higher supply current for lower unit cost and broader distributor availability - making MAX6865UK27D4L+T optimal for battery-critical, safety-aware designs requiring both hardware reset and software supervision.

Availability

MAX6865UK27D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and PDAs requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX6865UK27D4L+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 management, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6865UK27D4L+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for ultra-low-power battery-operated medical and portable electronics where deterministic reset behavior and multi-year battery life are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK27D4L+T?

The MAX6865UK27D4L+T has a factory-trimmed reset threshold of 2.700V with ±2.5% tolerance across -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix "27" corresponds to 2.700V nominal, and Electrical Characteristics specify VTH = VTH ±2.5%. The device guarantees valid reset assertion down to VCC = +1.1V regardless of threshold drift.

Does the MAX6865UK27D4L+T require external components for basic operation?

No, the MAX6865UK27D4L+T operates autonomously with no external components required. Its 1200ms reset timeout and 209s watchdog period are internally generated; the MR input features a 10kΩ internal pullup; and only a 0.1µF VCC bypass capacitor is recommended for noise immunity - not strictly required for functionality but essential for robust operation in real-world PCB layouts.

How does the watchdog timer in the MAX6865UK27D4L+T respond to software failures?

The MAX6865UK27D4L+T watchdog timer expires if the WDI pin remains static (high or low) for longer than 209s (typical). It clears on any detected edge (rising or falling), enabling flexible software supervision - such as toggling WDI at program entry points. Upon timeout, it asserts the same active-low RESET signal used for power faults, ensuring hardware-level recovery independent of firmware state.

What is the function of Pin 1 (RESET) on the MAX6865UK27D4L+T?

Pin 1 of the MAX6865UK27D4L+T is the active-low push-pull RESET output. It drives low during VCC brownout (below 2.700V), MR assertion, or watchdog timeout, and remains low for exactly 1200ms minimum after VCC recovers above threshold *and* MR is released. Unlike open-drain variants, this pin requires no external pullup and can directly drive CMOS reset inputs with 1.2mA sink capability at VCC ≥ 2.38V.

Can the MAX6865UK27D4L+T be used in systems with supply voltages below 2.7V?

Yes, the MAX6865UK27D4L+T functions reliably with VCC as low as +1.1V, though its reset threshold remains fixed at 2.700V. Below 2.7V, the device continuously asserts RESET (since VCC < VTH), providing fail-safe behavior. Its 170nA supply current at 1.8V (per Electrical Characteristics table) confirms operational integrity across the full 1.1V–5.5V range, making it suitable for deep-brownout detection in Li-ion battery discharge monitoring.