Analog Devices Inc./Maxim Integrated MAX6865UK37D3L+T

Overview

The MAX6865UK37D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 3.700V reset threshold (suffix "37"), 300ms minimum reset timeout (suffix "D3"), and 209s typical watchdog timeout (suffix "L"). It monitors VCC, responds to manual reset (MR) assertion, and triggers reset upon watchdog timer expiration - ideal for battery-powered glucose monitors and portable medical devices requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6865UK37D3L+T datasheet, MAX6865UK37D3L+T pinout, MAX6865UK37D3L+T application, or MAX6865UK37D3L+T equivalent, this page delivers verified functional identity, exact pin roles, confirmed timing parameters (tRP = 300ms min, tWD = 209s typ), true reset output configuration (active-high push-pull), and validated alternative options for low-power µP supervision in space-constrained, long-life systems.

Technical Context

The MAX6865UK37D3L+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 3.700V, when MR is pulled low, or when the watchdog input (WDI) remains static beyond 209s (typ). Its internal watchdog timer clears on any WDI edge, MR assertion, or active reset - enabling robust software execution monitoring without false timeouts.

This device uses BiCMOS process technology (2848 transistors) and guarantees valid reset output down to VCC = +1.1V. It features 10kΩ internal MR pullup, 200ns MR glitch rejection, and immunity to VCC transients ≤40µs at 100mV overdrive - critical for noisy battery-supplied environments where brownout resilience and noise immunity are non-negotiable.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), footprint-compatible with industry-standard 5-lead SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D3S+T and TPS3836K33DBVR, the MAX6865UK37D3L+T uniquely combines 209s watchdog timing, 3.700V precision threshold, and active-high push-pull output - delivering differentiated reliability for long-cycle medical firmware where both voltage accuracy and hang-detection duration are design-critical.

Availability

MAX6865UK37D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and wearable drug infusion pumps requiring stable component supply, long-term lifecycle support, and RoHS-compliant lead-free packaging.

Supply support for MAX6865UK37D3L+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 MAX6865UK37D3L+T belongs to the MAX6854–MAX6869 nanopower µP supervisory family, engineered specifically for ultra-low-power, safety-critical portable electronics where battery longevity, reset reliability, and watchdog-assisted firmware integrity are essential.

FAQ

What is the exact reset threshold voltage of the MAX6865UK37D3L+T?

The MAX6865UK37D3L+T has a factory-trimmed reset threshold voltage of 3.700V, with ±2.5% tolerance across -40°C to +85°C. This value is defined by the "37" suffix in the part number and is confirmed in Table 2 (Threshold Suffix Guide) of the official datasheet. The MAX6865UK37D3L+T guarantees valid reset assertion down to VCC = +1.1V, making it suitable for brownout detection in Li-ion-powered medical devices.

Does the MAX6865UK37D3L+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK37D3L+T includes a watchdog timer with a typical timeout period of 209 seconds, indicated by the "L" suffix in the part number. This long-interval watchdog is designed to detect catastrophic firmware hangs in applications like patient monitors where software routines may execute for minutes. The MAX6865UK37D3L+T watchdog clears on any WDI edge, MR assertion, or active reset - ensuring robustness against spurious timeouts.

What type of reset output does the MAX6865UK37D3L+T provide, and how is it configured?

The MAX6865UK37D3L+T provides an active-high push-pull reset output on Pin 1, as confirmed by its position in the Selector Guide (MAX6865 row, "Push-Pull ACTIVE HIGH" column) and Pin Description table. This eliminates the need for an external pullup resistor and directly drives standard µP reset inputs requiring high-asserted logic. The MAX6865UK37D3L+T output sources ≥500µA at VCC ≥2.38V with VOH ≥0.8×VCC, ensuring reliable interface across its operating voltage range.

What is the reset timeout period for the MAX6865UK37D3L+T, and how is it selected?

The MAX6865UK37D3L+T has a fixed minimum reset timeout period of 300ms, specified by the "D3" suffix per Table 4 (Reset Timeout Periods). This value is factory-programmed and not user-adjustable. The 300ms duration ensures sufficient time for µP clock stabilization, PLL lock, and memory initialization before release - critical for reliable boot in ARM-based medical SoCs. Unlike MAX6861–MAX6863 variants, the MAX6865UK37D3L+T does not feature pin-selectable timeout.

How does the manual reset (MR) input function on the MAX6865UK37D3L+T?

The MR input on the MAX6865UK37D3L+T is an active-low signal (Pin 3) with an internal 10kΩ pullup to VCC. Driving MR low initiates reset immediately, and the reset remains asserted for the full 300ms timeout after MR returns high. The MAX6865UK37D3L+T specifies 250ns MR-to-reset delay and 200ns glitch rejection, enabling clean pushbutton interfacing without external debounce. Leaving MR unconnected defaults to inactive (high) due to the internal pullup.