Analog Devices Inc./Maxim Integrated MAX6865UK36D4L+T

Overview

The MAX6865UK36D4L+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 3.6V reset threshold, 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It monitors VCC for brownout detection and asserts reset during power-up, power-down, or software hang-used in glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK36D4L+T datasheet, MAX6865UK36D4L+T pinout, MAX6865UK36D4L+T application, or MAX6865UK36D4L+T equivalent, this page delivers verified electrical specs, SOT23-5 terminal mapping, watchdog timing behavior, and validated alternatives for battery-powered µP systems requiring guaranteed reset assertion down to VCC = +1.1V.

Technical Context

The MAX6865UK36D4L+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 3.6V (±2.5%), MR is pulled low, or the watchdog timer expires after 209s (typ) of WDI inactivity. Its internal timer guarantees reset remains asserted for ≥1200ms after VCC recovery and MR deassertion.

Watchdog functionality clears on any WDI edge (rising/falling), MR assertion, or active reset-enabling robust software execution monitoring. Immunity to short VCC transients (<40µs at 100mV overdrive) and guaranteed RESET validity down to VCC = +1.1V support reliable operation in noisy, low-voltage battery systems.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK36D4L+T, MAX6864UK36D4L+T offers identical supervision parameters but inverted reset polarity, while TPS3838K33DBVR trades off watchdog capability and nanopower operation for lower unit cost in simple reset-only designs.

Availability

MAX6865UK36D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, and industrial handheld scanners requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for MAX6865UK36D4L+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 µP supervision with integrated watchdog timers, targeting battery-critical portable medical and IoT edge devices where reset reliability and multi-year runtime are essential.

FAQ

What is the exact reset threshold voltage of the MAX6865UK36D4L+T?

The MAX6865UK36D4L+T has a factory-trimmed reset threshold of 3.600V 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 "36" corresponds to 3.600V nominal. The MAX6865UK36D4L+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK36D4L+T require an external pullup resistor on the RESET pin?

No, the MAX6865UK36D4L+T uses a push-pull active-high RESET output, which actively drives high during reset assertion and low otherwise-eliminating the need for an external pullup. This simplifies design and reduces BOM count compared to open-drain alternatives. The MAX6865UK36D4L+T's internal driver ensures clean, rail-to-rail transitions without external components.

How does the watchdog timer in the MAX6865UK36D4L+T respond to WDI signal edges?

The MAX6865UK36D4L+T watchdog timer clears on any rising or falling edge at the WDI pin-no specific pulse width or duty cycle is required. A 150ns minimum pulse width is guaranteed detectable. If WDI remains static (high or low) longer than 209s (typ), the timer expires and triggers reset for 1200ms. The MAX6865UK36D4L+T resumes counting immediately after reset deassertion.

Can the MAX6865UK36D4L+T operate reliably below 1.8V supply voltage?

Yes, the MAX6865UK36D4L+T operates from VCC = +1.2V to +5.5V and guarantees valid RESET output down to VCC = +1.1V. Its 170nA supply current and internal voltage reference remain functional across this range, enabling use with single-cell LiFePO₄ (2.5–3.6V) or depleted alkaline/coin cells. This behavior is explicitly characterized in the Electrical Characteristics table.

What is the meaning of the "L" suffix in MAX6865UK36D4L+T?

The "L" suffix in MAX6865UK36D4L+T denotes the long watchdog timeout option: 209s typical (95s min, 487s max). This contrasts with the "S" suffix (3.3s typical), providing extended supervision for firmware with long idle cycles. The "L" is positioned after the reset timeout code "D4" per Maxim's ordering convention and is confirmed in Table 3 (Watchdog Timeout).