Analog Devices Inc./Maxim Integrated MAX6865UK36D6S+T

Overview

The MAX6865UK36D6S+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) functionality. It asserts an active-high push-pull RESET output when VCC drops below 3.600V (±2.5%), MR is pulled low, or the watchdog expires after 209s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) at 2.5V and guarantees valid reset operation down to VCC = +1.1V.

For engineers reviewing the MAX6865UK36D6S+T datasheet, MAX6865UK36D6S+T pinout, MAX6865UK36D6S+T application, or MAX6865UK36D6S+T equivalent, key selection criteria include its factory-trimmed 3.6V reset threshold, 1200ms minimum reset timeout (D6), 209s watchdog period (L suffix), active-high push-pull RESET output, and immunity to short VCC transients - all critical for battery-powered medical and portable electronics where deterministic power-on reset and software fault recovery are mandatory.

Technical Context

This device implements a dual-monitoring architecture: a precision bandgap-based voltage detector triggers reset on VCC undervoltage, while a digital watchdog timer monitors WDI edge transitions to detect firmware hangs. The internal 10kΩ MR pullup enables direct switch interfacing without external components, and the push-pull RESET output drives high to VCC with VOH ≥ 0.8×VCC (ISOURCE = 500µA).

Reset assertion is synchronized across three independent conditions - VCC falling below VTH, MR low, or WDI timeout - with guaranteed deassertion timing governed by the D6 timeout (600–1200ms). The watchdog's 209s typical timeout (L variant) is temperature-stable, varying <±15% over –40°C to +85°C, and supports pulse widths as short as 150ns.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 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 MAX6864UK36D6S+T, the MAX6865UK36D6S+T provides native active-high reset compatibility, eliminating level-shifting components; versus TPS3836K33DBVR, it adds critical watchdog supervision and longer, configurable reset timing essential for medical and industrial firmware integrity.

Availability

MAX6865UK36D6S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring systems, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK36D6S+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 connectivity in demanding environments.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting battery-critical medical, portable, and industrial applications where ultra-low ICC and deterministic reset behavior are non-negotiable.

FAQ

What is the exact reset threshold voltage of the MAX6865UK36D6S+T?

The MAX6865UK36D6S+T has a factory-trimmed reset threshold of 3.600V with ±2.5% tolerance over –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "36" corresponds to 3.600V nominal. The MAX6865UK36D6S+T maintains this accuracy without external calibration, making it suitable for monitoring 3.3V rails with defined brownout margins.

Does the MAX6865UK36D6S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK36D6S+T includes a watchdog timer with a typical timeout of 209 seconds, denoted by the "L" suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, which specifies that MAX6865UK_ _D_ _-T variants with "L" provide the longer timeout option. The timer clears on any WDI edge and triggers reset if no transition occurs within the timeout window.

What type of RESET output does the MAX6865UK36D6S+T provide?

The MAX6865UK36D6S+T provides an active-high push-pull RESET output, as confirmed in the Pin Description section for MAX6865 (page 8) and the Selector Guide (page 16). This means the RESET pin drives high to VCC when asserted and floats high-impedance when deasserted - eliminating the need for an external pullup resistor and enabling direct connection to µP reset inputs requiring active-high signaling.

What is the reset timeout period for the MAX6865UK36D6S+T?

The MAX6865UK36D6S+T features a D6 reset timeout period, specified as 600ms (min), 900ms (typ), and 1200ms (max) in Table 4 (Reset Timeout Periods). This extended timeout ensures reliable µP initialization in systems with slow-start power supplies or firmware requiring EEPROM or flash configuration before main code execution begins.

Is the MAX6865UK36D6S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK36D6S+T uses the standard 5-pin SOT23-5 package and shares identical pinout with MAX6864/MAX6866 (pin 1 = RESET, pin 2 = GND, pin 3 = MR, pin 4 = WDI, pin 5 = VCC), as shown in the Pin Configurations diagram (page 15). However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6856 (which lack WDI), so PCB layout must match the MAX6864–MAX6866 variant group.