Analog Devices Inc./Maxim Integrated MAX6865UK32D4S+T

Overview

The MAX6865UK32D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functions. It asserts an active-low push-pull RESET when VCC drops below 3.200V (±2.5%), MR is pulled low, or WDI fails to toggle within 3.3s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) at 2.5V and guarantees valid reset output down to VCC = +1.1V.

For engineers reviewing the MAX6865UK32D4S+T datasheet, MAX6865UK32D4S+T pinout, MAX6865UK32D4S+T application, or MAX6865UK32D4S+T equivalent, key selection criteria include its factory-trimmed 3.200V reset threshold, 1200ms minimum reset timeout (D4), 3.3s watchdog period (S suffix), push-pull active-high RESET output, and immunity to sub-40µs VCC transients - all critical for battery-powered medical and portable electronics.

Technical Context

This device implements a dual-monitoring architecture: a precision bandgap-based voltage detector with 2.5% threshold tolerance and hysteresis of 0.5%VTH, plus an RC-based watchdog timer that clears on any WDI edge and expires after 3.3s (typ) if inactive. The internal 10kΩ MR pullup ensures robust manual reset initiation without external components.

Its BiCMOS process enables guaranteed operation from VCC = 1.2V to 5.5V and reset validity down to 1.1V, while the 5-pin SOT23 footprint supports high-density PCB layouts. The D4 timeout (1200ms min) and S watchdog (3.3s typ) are factory-configured and non-adjustable - distinct from CT-selectable variants like MAX6861–MAX6863.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), 2.9mm × 1.6mm × 1.1mm body, 0.95mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK32D4S+T, the MAX6865UK32D4S+T provides active-high reset compatibility with modern low-voltage µPs; compared with TPS3838K33DBVR, it adds critical watchdog supervision and extended 1200ms timeout for robust firmware recovery - making it uniquely suited for safety-critical portable medical devices.

Availability

MAX6865UK32D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and feature cell phones requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6865UK32D4S+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 consumer applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-critical portable equipment, integrating voltage monitoring, manual reset, and watchdog functions into minimal 5-pin SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK32D4S+T?

The MAX6865UK32D4S+T has a factory-trimmed reset threshold voltage of 3.200V with ±2.5% tolerance over the full -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "32" corresponds to 3.200V nominal. The MAX6865UK32D4S+T uses this precise threshold to supervise 3.3V supply rails in portable electronics.

Does the MAX6865UK32D4S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK32D4S+T includes a watchdog timer with a typical timeout period of 3.3 seconds, indicated by the "S" suffix in the part number. The watchdog clears on any rising or falling edge at the WDI pin and expires only if WDI remains static longer than 3.3s (typ). This is documented in Table 3 (Watchdog Timeout) and applies specifically to MAX6864–MAX6869 variants including the MAX6865UK32D4S+T.

What type of RESET output does the MAX6865UK32D4S+T provide, and how is it configured?

The MAX6865UK32D4S+T provides a push-pull active-high RESET output, as confirmed by its position in the Selector Guide (row MAX6865) and Pin Description section. Unlike open-drain or active-low variants, this output drives high (to VCC) when deasserted and low (to GND) when asserted - eliminating the need for an external pullup resistor and simplifying interface to µPs with active-high reset inputs.

What is the reset timeout period for the MAX6865UK32D4S+T, and how is it set?

The MAX6865UK32D4S+T has a fixed minimum reset timeout period of 1200ms, denoted by the "D4" suffix in the part number. This value is factory-programmed and non-adjustable; it is not selected via external pins like the CT input on MAX6861–MAX6863. The 1200ms duration ensures sufficient time for complete µP initialization and peripheral configuration before release, as specified in Table 4 (Reset Timeout Periods).

Is the MAX6865UK32D4S+T compatible with 1.8V or 2.5V supply systems?

Yes, the MAX6865UK32D4S+T operates over a supply range of 1.2V to 5.5V and guarantees valid reset output down to VCC = 1.1V. Its 3.200V reset threshold is intended for 3.3V rails, but the device itself functions correctly at lower voltages - for example, drawing only 170nA at 2.5V and maintaining accurate threshold detection per electrical characteristics tables. This makes the MAX6865UK32D4S+T suitable for mixed-voltage systems where supervision occurs on the 3.3V domain while other circuitry runs at 1.8V or 2.5V.