Analog Devices Inc./Maxim Integrated MAX6865UK44D1S+T

Overview

The MAX6865UK44D1S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (4.266V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (3.3s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and maintains reset for ≥10ms after recovery - ideal for battery-powered glucose monitors and portable medical devices requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6865UK44D1S+T datasheet, MAX6865UK44D1S+T pinout, MAX6865UK44D1S+T application, or MAX6865UK44D1S+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options - all grounded in Maxim's official specifications for the precise part number.

Technical Context

The MAX6865UK44D1S+T implements a dual-trigger reset architecture: one path responds to VCC falling below 4.266V ±2.5%, while a second path activates on MR low or WDI inactivity exceeding 3.3s (typ). Its internal watchdog timer clears on any WDI edge (rising/falling), MR assertion, or RESET assertion - preventing false timeouts during valid software execution.

Reset deassertion follows a fixed 10ms minimum timeout after VCC rises above threshold *and* MR is released *and* watchdog is cleared. The active-high push-pull RESET output is referenced to VCC and guarantees VOH ≥0.8×VCC at ISOURCE = 500µA (VCC ≥2.38V), enabling direct interfacing with µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (indicated by "+T" suffix), footprint-compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK44D1S+T, MAX6864UK44D1S+T offers identical supervision parameters but inverted reset polarity, while TPS3836K33DBVR lacks watchdog capability and draws ~10× more current - making MAX6865UK44D1S+T the sole choice for ultra-low-power, dual-trigger (voltage + software) reset assurance.

Availability

MAX6865UK44D1S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial handheld terminals requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK44D1S+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 demanding industrial, medical, and communications applications.

The MAX68xx family was designed specifically for nanopower, multi-function supervision in space-constrained, battery-critical systems - integrating voltage monitoring, manual reset, and watchdog into minimal 5-pin SOT23 footprints without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK44D1S+T?

The MAX6865UK44D1S+T has a factory-trimmed reset threshold voltage of 4.266V, with ±2.5% tolerance across -40°C to +85°C. This value is confirmed by Maxim's Threshold Suffix Guide (suffix "44") and Electrical Characteristics table, and applies specifically to the MAX6865UK44D1S+T - not the broader MAX686x family. The threshold remains stable over temperature, with normalized variation <±0.5% from -40°C to +85°C.

Does the MAX6865UK44D1S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK44D1S+T includes a watchdog timer with a typical timeout period of 3.3s, designated by the "S" suffix in the part number. This is verified in Maxim's Watchdog Timeout table (Table 3) and Electrical Characteristics section. The timer clears on any rising or falling edge at the WDI pin, and expires only if WDI remains static (high or low) beyond 3.3s - providing robust software execution monitoring without requiring CPU polling.

What type of RESET output does the MAX6865UK44D1S+T provide, and how is it configured?

The MAX6865UK44D1S+T provides an active-high push-pull RESET output, confirmed by its pin description (Pin 1 = RESET, active-high) and Selector Guide. This means the output drives high during reset assertion and low during normal operation - eliminating the need for an external pullup resistor. It is referenced to VCC and guarantees VOH ≥0.8×VCC at 500µA source current (VCC ≥2.38V), enabling direct interface with most µP reset inputs.

What is the minimum reset timeout period for the MAX6865UK44D1S+T, and how is it set?

The MAX6865UK44D1S+T has a fixed minimum reset timeout period of 10ms, indicated by the "D1" suffix in the part number. This value is specified in Table 4 (Reset Timeout Periods) and is guaranteed across -40°C to +85°C. Unlike pin-selectable variants (e.g., MAX6861), the MAX6865UK44D1S+T does not use a CT pin - its timeout is factory-programmed and immutable, ensuring predictable reset hold time for µP power stabilization.

Is the MAX6865UK44D1S+T compatible with 1.8V or 2.5V supply rails?

Yes, the MAX6865UK44D1S+T operates across VCC = 1.2V to 5.5V and guarantees RESET validity down to VCC = +1.1V. Its 4.266V reset threshold is intended for monitoring higher rails (e.g., 4.3V LiMnO₂ batteries), but the IC itself functions correctly at 1.8V or 2.5V supply - drawing only 170nA typical current at 1.8V. This makes it suitable for mixed-voltage systems where the supervisor runs from a lower auxiliary rail while monitoring a higher main rail.