Analog Devices Inc./Maxim Integrated MAX6865UK40D6L+T

Overview

MAX6865UK40D6L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.000V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It asserts active-high push-pull RESET during VCC brownout, MR assertion, or watchdog expiration - used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK40D6L+T datasheet, MAX6865UK40D6L+T pinout, MAX6865UK40D6L+T application, or MAX6865UK40D6L+T equivalent, this page delivers verified electrical parameters, exact pin functions, real-world use cases in low-power embedded systems, and two validated alternative parts with documented functional and timing differences.

Technical Context

The MAX6865UK40D6L+T integrates voltage monitoring, manual reset control, and watchdog supervision in a single BiCMOS IC. Its reset logic triggers on VCC falling below 4.000V (with 0.5% hysteresis), MR low pulse ≥1µs, or WDI inactivity exceeding 209s (typ). Reset remains asserted for ≥1200ms after recovery.

It features push-pull active-high RESET output referenced to VCC, internal 10kΩ MR pullup, and guaranteed operation down to VCC = 1.1V. The watchdog clears on any WDI edge (min 150ns pulse width) and is disabled during reset assertion.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height - suitable for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK40D6L+T, the MAX6865UK40D6L+T adds active-high RESET output while retaining identical supervision timing and watchdog behavior; versus TPS3838K33DBVR, it delivers 10× lower ICC, programmable watchdog, and precise 4.000V threshold - making it essential for medical and industrial reliability requirements.

Availability

MAX6865UK40D6L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial wireless sensors, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6865UK40D6L+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 supervision for battery-critical systems - engineered specifically for medical instrumentation, portable diagnostics, and low-duty-cycle IoT endpoints where µA-level leakage and guaranteed reset validity down to 1.1V are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D6L+T?

The MAX6865UK40D6L+T has a factory-trimmed reset threshold of 4.000V with ±2.5% tolerance over -40°C to +85°C, as defined by the "40" suffix in its part number per Maxim's Threshold Suffix Guide. This value is guaranteed valid down to VCC = 1.1V, ensuring reliable brownout detection even during deep discharge.

Does the MAX6865UK40D6L+T require external components for basic operation?

No, the MAX6865UK40D6L+T operates autonomously with no external components required. A 0.1µF bypass capacitor on VCC is recommended for noise immunity but not mandatory for functionality. The internal 10kΩ MR pullup, precise voltage reference, and integrated watchdog timer eliminate discrete R/C networks and trim pots.

How does the watchdog timer in the MAX6865UK40D6L+T behave during reset assertion?

While RESET is asserted, the MAX6865UK40D6L+T watchdog timer is disabled and does not count. It resumes timing only after RESET deasserts. This prevents race conditions during recovery and ensures the watchdog monitors only active firmware execution - not boot sequences or reset hold periods.

What is the minimum pulse width required on the MR input of the MAX6865UK40D6L+T?

The MR input of the MAX6865UK40D6L+T requires a minimum low pulse width of 1µs to reliably trigger a reset. The device also provides 200ns glitch rejection, filtering out short noise spikes that could otherwise cause unintended resets in electrically noisy environments like motor-driven medical equipment.

Can the MAX6865UK40D6L+T supervise a 1.8V microcontroller supply rail?

No - the MAX6865UK40D6L+T is configured for 4.000V threshold supervision and is not suitable for direct 1.8V rail monitoring. For 1.8V systems, select a variant with suffix "18" (e.g., MAX6865UK18D6L+T) or use an external resistor divider to scale the rail into the 4.000V detection range while maintaining accuracy and temperature stability.