Analog Devices Inc./Maxim Integrated MAX6865UK40D1L+T

Overview

The MAX6865UK40D1L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (4.000V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 10ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK40D1L+T datasheet, MAX6865UK40D1L+T pinout, MAX6865UK40D1L+T application, or MAX6865UK40D1L+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 10ms reset timeout, and L-suffix 209s watchdog period - critical for low-power embedded systems requiring deterministic fault recovery.

Technical Context

This device implements a dual-trigger reset architecture: one path responds to VCC falling below 4.000V ±2.5%, while a second path activates on MR low or WDI inactivity exceeding 209s (typ). The internal watchdog timer clears on any WDI edge, MR assertion, or RESET assertion - enabling robust software execution monitoring without external timing components.

Its push-pull active-low RESET output drives directly to GND or VCC (VOH ≥ 0.8×VCC, VOL ≤ 0.3V at ISINK = 1.2mA), eliminating need for pull-up resistors. The MR input features 10kΩ internal pull-up and 250ns MR-to-reset delay, supporting momentary switch interfaces without external debounce.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height - 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 MAX6864UK40D1L+T, the MAX6865UK40D1L+T offers identical supervision but is distinguished by its part numbering convention indicating active-high RESET variants in the family - though this specific variant retains active-low output. Against TPS3838K33DBVR, MAX6865UK40D1L+T delivers 10× lower ICC and integrated watchdog, enabling longer battery life and safer firmware operation.

Availability

MAX6865UK40D1L+T is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered PDAs, wireless patient monitors, and low-power IoT edge nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK40D1L+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting battery-critical portable electronics - emphasizing ultra-low ICC, wide VCC range, and integrated watchdog for firmware reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D1L+T?

The MAX6865UK40D1L+T has a factory-trimmed reset threshold of 4.000V 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 "40" corresponds to 4.000V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for brownout detection on 3.3V and 5V rails.

Does the MAX6865UK40D1L+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK40D1L+T includes a watchdog timer with a typical timeout period of 209s, indicated by the "L" suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and Ordering Information, where "L" denotes the long timeout option (95s to 487s min/max). The timer resets on any WDI edge, MR assertion, or RESET assertion - ensuring reliable software hang detection.

What is the reset timeout duration for the MAX6865UK40D1L+T, and how is it selected?

The MAX6865UK40D1L+T has a fixed minimum reset timeout of 10ms, denoted by the "D1" suffix. This value is specified in Table 4 (Reset Timeout Periods) as D1 = 10ms (min)/15ms (typ)/25ms (max). Unlike MAX6861–MAX6863, this variant does not feature a CT pin for timeout selection - the 10ms period is factory-configured and non-adjustable.

What type of RESET output does the MAX6865UK40D1L+T provide, and what are its drive capabilities?

The MAX6865UK40D1L+T provides an active-low push-pull RESET output. As confirmed in the Pin Description (page 8) and Selector Guide (page 16), pin 1 drives low to GND (VOL ≤ 0.3V at ISINK = 1.2mA) and high to VCC (VOH ≥ 0.8×VCC at ISOURCE = 500µA). This eliminates need for external pull-up resistors and supports direct connection to standard CMOS µP reset inputs.

Is the MAX6865UK40D1L+T pin-compatible with other devices in the MAX68xx family?

Yes, the MAX6865UK40D1L+T uses the standard 5-pin SOT23-5 package and shares identical pinout with MAX6864, MAX6866–MAX6869 (pin 1=RESET, 2=GND, 3=MR, 4=WDI, 5=VCC), as shown in the Pin Configurations diagram (page 15). This allows drop-in replacement among L-suffix watchdog variants without PCB changes - provided RESET polarity and timeout requirements match.