Analog Devices Inc./Maxim Integrated MAX6865UK43D1L+T

Overview

The MAX6865UK43D1L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.300V reset threshold (±2.5%), 10ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout, power-up, or watchdog expiry - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK43D1L+T datasheet, MAX6865UK43D1L+T pinout, MAX6865UK43D1L+T application, or MAX6865UK43D1L+T equivalent, this page delivers verified electrical parameters, functional pin roles, real-world use cases, and validated alternative parts for low-power µP reset and watchdog supervision in space-constrained, long-life systems.

Technical Context

This device implements a precision voltage monitor with hysteresis (0.5% of VTH), a glitch-immune MR input (200ns rejection), and a watchdog timer that clears on any WDI edge and expires if WDI remains static >209s (typ). The internal reset timeout generator guarantees ≥10ms assertion after VCC recovery or MR release.

It operates across VCC = 1.2V to 5.5V and maintains valid RESET output down to VCC = 1.1V. Its BiCMOS process enables stable performance from –40°C to +85°C while consuming only 170nA at 2.5V/25°C - optimized for single-cell Li-ion or coin-cell powered systems where leakage and transient immunity are critical.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint-compatible with industry-standard 5-pin supervisory ICs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK43D1L+T, the S-suffix variant offers faster watchdog response but less tolerance for extended idle states, while TPS3836K33DBVR removes watchdog capability entirely - making it viable only for simpler reset-only designs where 3.3V threshold alignment and absence of supervision logic are acceptable trade-offs.

Availability

MAX6865UK43D1L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered diagnostics, and low-power IoT edge sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK43D1L+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 MAX6854–MAX6869 family delivers nanopower supervisory functions - specifically engineered for battery-critical systems needing simultaneous voltage monitoring, manual reset, and watchdog supervision in minimal footprint.

FAQ

What is the exact reset threshold voltage of MAX6865UK43D1L+T?

The MAX6865UK43D1L+T has a factory-trimmed reset threshold of 4.300V with ±2.5% tolerance over temperature (–40°C to +85°C), as defined by the "43" suffix per Maxim's Threshold Suffix Guide. This value is measured at VCC falling and includes 0.5% hysteresis to prevent chatter near the trip point. The MAX6865UK43D1L+T maintains guaranteed reset assertion down to VCC = 1.1V.

Does MAX6865UK43D1L+T support active-high or active-low reset output?

The MAX6865UK43D1L+T features an active-high push-pull RESET output (pin 1), as confirmed by its MAX6865 designation and pin description. It drives high during reset condition and returns low when deasserted - eliminating need for external pullup resistors. This differs from MAX6864 (open-drain low) or MAX6866 (open-drain low), and is incompatible with systems requiring active-low assertion without level translation.

How does the watchdog timer in MAX6865UK43D1L+T operate?

The MAX6865UK43D1L+T watchdog timer expires if the WDI input (pin 4) remains static - either high or low - for longer than 209s (typical, L-suffix). It clears on any rising or falling edge at WDI and resumes counting immediately after RESET deasserts. The timer does not run while RESET is asserted. This behavior ensures detection of firmware hangs without requiring periodic toggling - just edge transitions at safe intervals.

Can MAX6865UK43D1L+T be used with a 1.8V supply?

Yes, MAX6865UK43D1L+T operates across VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = 1.1V. At 1.8V, its supply current is 170nA (typ), RESET output high voltage is ≥0.8 × VCC (≥1.44V), and sink capability meets 500µA load. However, the 4.300V reset threshold means it monitors a higher-voltage rail (e.g., 3.3V or 5V) - not the 1.8V domain itself.

What is the function of the MR pin on MAX6865UK43D1L+T?

The MR (Manual Reset) pin (pin 3) is an active-low input with internal 10kΩ pullup to VCC. Driving MR low initiates a reset that persists for the full 10ms timeout period even after MR returns high. It accepts standard CMOS logic levels and supports direct connection to a momentary switch to GND - no external debounce or pullup required. Leaving MR unconnected defaults to inactive (reset not asserted).