Analog Devices Inc./Maxim Integrated MAX6865UK38D3L+T

Overview

The MAX6865UK38D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.800V reset threshold (suffix "38"), 150ms minimum reset timeout (suffix "D3"), and watchdog timer with 209s typical timeout (suffix "L"). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-powered medical and portable electronics requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6865UK38D3L+T datasheet, MAX6865UK38D3L+T pinout, MAX6865UK38D3L+T application, or MAX6865UK38D3L+T equivalent, this page delivers verified specifications, functional pin mapping, real-world use cases in glucose monitors and patient monitors, and two validated alternative parts with documented technical and application differences.

Technical Context

The MAX6865UK38D3L+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 3.800V (±2.5%), 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 in safety-critical embedded systems.

This device uses BiCMOS process technology (2848 transistors) and guarantees valid push-pull active-high 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 - ensuring reliable operation in noisy, low-power environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), 2.9mm × 1.6mm footprint, 1.1mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK38D3L+T and TPS3838K33DBVR, the MAX6865UK38D3L+T uniquely combines 3.800V threshold accuracy, active-high push-pull RESET, 209s watchdog, and 170nA supply current - making it optimal for compact, long-life medical and portable devices requiring deterministic reset signaling and runtime code integrity verification.

Availability

MAX6865UK38D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign monitors, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6865UK38D3L+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 - specifically engineered for battery-constrained, safety-critical portable electronics requiring guaranteed reset behavior and runtime firmware monitoring.

FAQ

What is the exact reset threshold voltage of the MAX6865UK38D3L+T?

The MAX6865UK38D3L+T has a factory-trimmed reset threshold of 3.800V, with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "38" corresponds to 3.800V nominal. The MAX6865UK38D3L+T maintains this accuracy without external calibration.

Does the MAX6865UK38D3L+T support active-high reset output?

Yes, the MAX6865UK38D3L+T provides a push-pull active-high RESET output (Pin 1), as confirmed in the MAX6865-specific pin description on page 8 of the datasheet. This eliminates the need for an external pullup resistor and directly interfaces with µPs requiring high-true reset assertion - a key differentiator from MAX6864 variants.

What is the watchdog timeout period for the MAX6865UK38D3L+T?

The MAX6865UK38D3L+T features a watchdog timeout period of 209s typical (L suffix), with min/max values of 95s and 487s over temperature. This is specified in Table 3 (Watchdog Timeout) and applies when WDI remains static; the timer resets on any WDI edge, MR assertion, or active reset condition.

How does the MAX6865UK38D3L+T handle supply voltage transients?

The MAX6865UK38D3L+T is immune to VCC transients ≤40µs in duration when the overdrive is 100mV (per Typical Operating Characteristic Figure 5). This transient immunity prevents false resets during switching noise or load dump events - critical for reliability in portable medical devices where power integrity cannot be assumed.

Is the MAX6865UK38D3L+T compatible with 1.8V microcontrollers?

Yes, the MAX6865UK38D3L+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. Its MR input accepts logic levels referenced to VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), and its 170nA supply current at 1.8V makes it fully compatible with ultra-low-voltage µCs used in energy-harvesting sensors and wearables.