Analog Devices Inc./Maxim Integrated MAX6865UK35D2L+T

Overview

The MAX6865UK35D2L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (3.5V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK35D2L+T datasheet, MAX6865UK35D2L+T pinout, MAX6865UK35D2L+T application, or MAX6865UK35D2L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset timeout options, and compatibility with low-voltage µP systems requiring long battery life and robust fault recovery.

Technical Context

This device implements a dual-trigger reset architecture: one path responds to VCC falling below 3.5V ±2.5%, another activates on MR low or WDI inactivity exceeding 209s (typ). The internal watchdog timer clears on any WDI edge, MR assertion, or RESET activation - preventing false timeouts during system resets or initialization sequences.

The push-pull active-high RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V), while VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V). MR features 10kΩ internal pullup and 1µs minimum pulse width support, enabling direct connection to momentary switches without external debounce.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK35D2L+T, the MAX6865UK35D2L+T provides native active-high RESET compatibility, eliminating external inverters. Against TPS3837K33DBVR, it delivers 10× lower ICC and adds critical watchdog supervision - essential for autonomous medical and industrial edge nodes.

Availability

MAX6865UK35D2L+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and low-power industrial sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK35D2L+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 MAX68xx family targets ultra-low-power microprocessor supervision in space-constrained, battery-operated systems - emphasizing nanopower operation, robust reset timing, and integrated watchdog functionality for safety-critical firmware monitoring.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D2L+T?

The MAX6865UK35D2L+T has a factory-trimmed reset threshold of 3.500V 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 "35" corresponds to 3.500V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for systems with wide input voltage ranges.

Does the MAX6865UK35D2L+T require external components for basic operation?

No, the MAX6865UK35D2L+T operates autonomously with no external components required. It integrates a 10kΩ internal pullup on MR, precision voltage reference, and timing circuitry. Only a 0.1µF ceramic bypass capacitor from VCC to GND is recommended for noise suppression - a standard practice for all linear regulators and supervisors.

How does the watchdog timer in the MAX6865UK35D2L+T clear and time out?

The MAX6865UK35D2L+T watchdog timer clears on any rising or falling edge at WDI, on MR assertion, or during RESET activation. It times out after 209s (typical, L-suffix), triggering a reset for the configured 40ms period. The timer remains suspended while RESET is asserted, resuming only after deassertion - preventing interference during µP reboot sequences.

Can the MAX6865UK35D2L+T interface directly with a 1.8V microcontroller?

Yes, the MAX6865UK35D2L+T supports VCC from 1.2V to 5.5V and guarantees RESET output performance down to VCC = +1.1V. Its VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V) and VOL ≤ 0.3V at ISINK = 1.2mA ensures clean logic levels for 1.8V µPs. MR input thresholds scale with VCC (VIH = 0.7×VCC), enabling direct CMOS interfacing.

What is the purpose of the "L" suffix in MAX6865UK35D2L+T?

The "L" suffix in MAX6865UK35D2L+T specifies the watchdog timeout option: 95s (min) / 209s (typ) / 487s (max). This contrasts with the "S" suffix (1.5s/3.3s/7.75s). The L option is selected for applications with long firmware loops or infrequent WDI toggling - such as medical data loggers performing hourly sensor reads - to avoid nuisance resets.