Analog Devices Inc./Maxim Integrated MAX6865UK29D4L+T

Overview

The MAX6865UK29D4L+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 2.925V reset threshold (suffix "29"), 1200ms minimum reset timeout (suffix "D4"), and 209s typical watchdog timeout (suffix "L"). It monitors VCC, responds to manual reset (MR) input, and triggers reset on watchdog timer expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK29D4L+T datasheet, MAX6865UK29D4L+T pinout, MAX6865UK29D4L+T application, or MAX6865UK29D4L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-power systems requiring long watchdog intervals and minimal quiescent current.

Technical Context

The MAX6865UK29D4L+T implements a dual-function supervision architecture: a precision voltage monitor with ±2.5% threshold accuracy over temperature and a watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

This device belongs to the MAX6864–MAX6869 variant group with active-high push-pull RESET output, fixed D4 (1200ms min) reset timeout, and L-suffix (209s typ) watchdog period. It asserts reset when VCC falls below 2.925V, MR is pulled low, or WDI stalls - and holds RESET high for ≥1200ms after recovery, ensuring µP initialization completes before release.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), 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 MAX6865UK29D4S+T and TPS3837K29QDBVR, the MAX6865UK29D4L+T uniquely balances ultra-low power (170nA), long-interval watchdog (209s), and active-high push-pull output - making it the sole option among these three for battery-critical, long-loop, medical-grade supervision.

Availability

MAX6865UK29D4L+T is available at Aetrix Electronics and suitable for glucose monitoring systems, patient vital sign loggers, and wireless medical telemetry units requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for MAX6865UK29D4L+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 demanding applications in industrial, medical, and communications markets.

The MAX6864–MAX6869 product line delivers nanopower supervisory circuits optimized for battery-operated medical and portable electronics, emphasizing ultra-low ICC, wide VCC range, and configurable watchdog timing - all in miniature SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK29D4L+T?

The MAX6865UK29D4L+T has a factory-trimmed reset threshold voltage of 2.925V, with ±2.5% tolerance over temperature (−40°C to +85°C). This value is defined by the "29" suffix in the part number and is verified per Table 2 (Threshold Suffix Guide) in the official datasheet. The MAX6865UK29D4L+T asserts reset when VCC falls below this threshold and holds reset for ≥1200ms after VCC recovers.

Does the MAX6865UK29D4L+T support active-high or active-low reset output?

The MAX6865UK29D4L+T features an active-high push-pull RESET output (pin 1), as confirmed by its placement in the MAX6865 row of the Selector Guide and its functional description in the MAX6864/MAX6865/MAX6866 Pin Description section. This eliminates the need for an external pullup resistor and ensures strong logic-high drive into the µP's reset input, unlike open-drain or active-low variants.

What is the watchdog timeout behavior of the MAX6865UK29D4L+T?

The MAX6865UK29D4L+T provides a watchdog timeout period of 209s (typical), with a min–max range of 95s to 487s, denoted by the "L" suffix. The internal watchdog timer clears on any rising or falling edge at WDI (pin 4) and expires only if WDI remains static beyond this interval - triggering a reset assertion for the full 1200ms timeout period.

Can the MAX6865UK29D4L+T operate reliably at VCC = 1.5V?

Yes, the MAX6865UK29D4L+T operates over VCC = 1.2V to 5.5V and guarantees valid reset assertion down to VCC = +1.1V. At 1.5V, all core functions - including voltage monitoring, MR response, and watchdog timing - remain fully specified and functional per Electrical Characteristics table limits, making it suitable for deeply discharged lithium coin cells.

Is the MAX6865UK29D4L+T pin-compatible with other SOT23-5 supervisors?

The MAX6865UK29D4L+T uses standard 5-pin SOT23-5 pinout (RESET, GND, MR, WDI, VCC) and is pin-compatible with the MAX6864–MAX6869 family. However, it is not pin-compatible with MAX6854–MAX6856 or MAX6861–MAX6863 variants, which assign different functions (e.g., CT or I.C.) to pin 1 or pin 4. Always verify pin mapping using the MAX6864/MAX6865/MAX6866 Pin Description section.