Analog Devices Inc./Maxim Integrated MAX6865UK44D4L+T

Overview

The MAX6865UK44D4L+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 4.266V to 4.484V reset threshold (suffix "44"), 1200ms minimum reset timeout (suffix "D4"), and 95s to 487s watchdog timeout (suffix "L"). It integrates voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functions, and is used to ensure reliable power-up sequencing and fault recovery in battery-powered medical and portable electronics.

For engineers reviewing the MAX6865UK44D4L+T datasheet, MAX6865UK44D4L+T pinout, MAX6865UK44D4L+T application, or MAX6865UK44D4L+T equivalent, this page delivers verified technical context, exact pin roles, real-world use cases, and validated alternative options for low-power µP reset supervision with watchdog capability.

Technical Context

The MAX6865UK44D4L+T implements a dual-trigger reset assertion mechanism: it asserts reset when VCC falls below its 4.266V–4.484V threshold, when MR is pulled low, or when the WDI input remains static beyond its 95s–487s watchdog timeout period. Its internal timer guarantees reset remains asserted for ≥1200ms after VCC recovers and MR deasserts.

This device uses BiCMOS process technology, supports operation down to VCC = 1.1V with guaranteed RESET validity, and features 200ns MR glitch rejection and 150ns minimum WDI pulse width detection - enabling robust operation in noisy, low-voltage embedded systems.

Key Specifications

Pinout & Package

MAX6865UK44D4L+T is housed in a lead-free 5-pin SOT23-5 package (JEDEC MO-178AA), with 0.95mm pitch and 2.9mm × 1.6mm footprint - compatible with standard reflow profiles and space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK44D4L+T, MAX6864UK44D4L+T offers identical supervision thresholds and timing but requires external biasing, while TPS3838K33DBVR trades watchdog capability and nanopower operation for lower unit cost and simpler qualification in non-critical systems.

Availability

MAX6865UK44D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld terminals, and smart wearable health trackers requiring stable component supply with long-term lifecycle support.

Supply support for MAX6865UK44D4L+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 was engineered specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer electronics - prioritizing nanoscale ICC, guaranteed brownout reset, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage range for MAX6865UK44D4L+T?

The MAX6865UK44D4L+T has a factory-trimmed reset threshold of 4.266V (minimum), 4.375V (typical), and 4.484V (maximum), corresponding to suffix "44" per Maxim's Threshold Suffix Guide. This range is specified over the full -40°C to +85°C operating temperature and guarantees ±2.5% tolerance relative to the nominal value. The MAX6865UK44D4L+T uses this threshold to monitor 3.3V or 4.5V system rails without external calibration.

Does MAX6865UK44D4L+T support both manual reset and watchdog functions simultaneously?

Yes, the MAX6865UK44D4L+T fully supports concurrent manual reset (MR) and watchdog timer (WDI) operation. A low pulse on MR asserts reset independently of VCC level or WDI state, and the watchdog timer expires if WDI remains static beyond its 95s–487s timeout window. Both triggers cause the same active-high RESET output to assert for the full 1200ms timeout period. The MAX6865UK44D4L+T clears the watchdog timer on any MR assertion or RESET activation.

What is the function of Pin 1 (RESET) on MAX6865UK44D4L+T?

Pin 1 of the MAX6865UK44D4L+T is the active-high push-pull RESET output. When asserted, it drives high (VOH ≥ 0.8×VCC) to signal reset to the microprocessor; when deasserted, it drives low (VOL ≤ 0.3V) to release reset. Unlike open-drain variants, it requires no external pullup and can directly interface to µP reset pins expecting high-true logic. The MAX6865UK44D4L+T guarantees this output remains valid down to VCC = 1.1V.

Can MAX6865UK44D4L+T operate from a 1.8V supply?

Yes, the MAX6865UK44D4L+T operates across VCC = 1.2V to 5.5V, including 1.8V. At 1.8V, its supply current is 170nA (typical), reset threshold remains accurate (4.266V–4.484V), and RESET output meets VOH ≥ 0.8×VCC and VOL ≤ 0.3V specifications under load. However, note that the 4.266V threshold exceeds 1.8V - so the device will assert reset continuously unless VCC is ≥ ~4.3V. Thus, MAX6865UK44D4L+T is intended for supervision of higher-voltage rails (e.g., 4.5V or 5V), not 1.8V domains.

How does the watchdog timeout period work on MAX6865UK44D4L+T?

The MAX6865UK44D4L+T watchdog timeout is fixed at 95s (minimum), 209s (typical), and 487s (maximum), denoted by suffix "L". The internal timer resets on every rising or falling edge at WDI (Pin 4); if no edge occurs within the timeout window, RESET asserts for 1200ms. The timer pauses while RESET is asserted and resumes counting upon deassertion. This behavior ensures MAX6865UK44D4L+T reliably detects firmware hangs without requiring precise software timing.