Analog Devices Inc./Maxim Integrated MAX6865UK35D4L+T

Overview

The MAX6865UK35D4L+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 3.5V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout (L-suffix). It asserts an active-high push-pull RESET during VCC brownout, MR assertion, or watchdog expiration - used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK35D4L+T datasheet, MAX6865UK35D4L+T pinout, MAX6865UK35D4L+T application, or MAX6865UK35D4L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset delay absence (fixed D4 timeout), and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device integrates voltage monitoring, a manual reset input (MR), and a watchdog timer (WDI) with internal 10kΩ MR pullup and glitch rejection (200ns). The watchdog clears on any WDI edge and expires if WDI remains static beyond 209s (typ), triggering a full reset timeout cycle.

The reset logic uses a precision bandgap reference for threshold stability (±2.5% over -40°C to +85°C) and guarantees valid RESET output down to VCC = +1.1V. Its push-pull active-high RESET output drives directly into µP reset inputs without external components, supporting CMOS-level interfacing across its full 1.2V–5.5V operating range.

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 MAX6865UK35D4L+T, MAX6864UK35D4L+T requires µP-level logic inversion and lacks active-high output, while TPS3837K33DBVR trades 10× higher supply current and no watchdog for broader distributor stock and lower unit cost in non-critical applications.

Availability

MAX6865UK35D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and industrial handheld scanners requiring stable component supply, long-lifecycle assurance, and lead-free compliance.

Supply support for MAX6865UK35D4L+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 interface applications in industrial, medical, and communications markets.

The MAX68xx family delivers nanopower supervisory functions targeting battery-critical portable medical and instrumentation systems, emphasizing ultra-low ICC, wide VCC range, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D4L+T?

The MAX6865UK35D4L+T has a factory-trimmed reset threshold of 3.500V 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 "35" corresponds to 3.500V nominal. The MAX6865UK35D4L+T maintains this specification without external calibration or trimming.

Does the MAX6865UK35D4L+T support active-high or active-low reset output?

The MAX6865UK35D4L+T features an active-high push-pull RESET output, as defined in its pin description and Selector Guide. Pin 1 delivers a high-voltage signal during reset assertion - unlike MAX6864 variants which offer active-low. This matches µPs requiring high-valid reset inputs without external inverters.

What is the watchdog timeout period for the MAX6865UK35D4L+T?

The MAX6865UK35D4L+T implements a watchdog timeout period of 209s typical (L-suffix), with min/max values of 95s and 487s. This is specified in Table 3 (Watchdog Timeout) and applies across the full operating temperature range. The timer resets on any WDI edge and triggers reset if WDI remains static beyond this window.

Can the MAX6865UK35D4L+T operate below 1.5V supply voltage?

Yes - the MAX6865UK35D4L+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. Its internal circuitry remains functional at 1.2V, enabling use in single-cell alkaline or NiMH systems where voltage sags below 1.5V during discharge.

Is the MR input of the MAX6865UK35D4L+T internally pulled up?

Yes, the MR input of the MAX6865UK35D4L+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description section. This allows direct connection of a momentary switch to GND without external components, and supports CMOS-level drive from µP GPIOs.