Analog Devices Inc./Maxim Integrated MAX6865UK43D2L+T

Overview

The MAX6865UK43D2L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (4.300V ±2.5% reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical 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 requiring long shelf life and reliable power-on reset.

For engineers reviewing the MAX6865UK43D2L+T datasheet, MAX6865UK43D2L+T pinout, MAX6865UK43D2L+T application, or MAX6865UK43D2L+T equivalent, key selection criteria include its factory-trimmed 4.300V reset threshold, 209s watchdog timeout (L-suffix), 40ms reset timeout (D2), active-high push-pull output, and guaranteed reset validity down to VCC = +1.1V - all critical for low-voltage, safety-critical embedded systems.

Technical Context

The MAX6865UK43D2L+T implements a dual-trigger reset architecture: one path monitors VCC against a precision bandgap-based 4.300V threshold with 0.5% hysteresis, while a second path detects WDI inactivity exceeding 209s (typ). Its internal watchdog clears on any WDI edge, MR assertion, or RESET assertion - preventing false timeouts during software initialization or interrupt handling.

This device uses BiCMOS process technology to achieve 170nA supply current at 2.5V/25°C while maintaining robust noise immunity: it rejects VCC transients ≤40µs at 100mV overdrive and guarantees valid RESET output down to VCC = 1.1V, enabling operation across wide battery discharge curves in portable healthcare equipment.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, -40°C to +85°C operating range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK43D2L+T, the MAX6865UK43D2L+T adds no functional difference for this configuration but shares identical pinout and electrical behavior; versus TPS3837K33DBVR, it delivers 15× lower supply current, 4.3V precision threshold, and integrated watchdog - making it superior for next-generation portable medical devices.

Availability

The MAX6865UK43D2L+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and remote wireless sensors requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK43D2L+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 high-performance analog and mixed-signal semiconductor solutions for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in portable healthcare and battery-constrained IoT endpoints, emphasizing nanopower operation, precision voltage thresholds, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK43D2L+T?

The MAX6865UK43D2L+T has a factory-trimmed reset threshold of 4.300V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is encoded in the "43" suffix per Maxim's Threshold Suffix Guide (Table 2), and is measured at VCC falling. The device guarantees reset assertion when VCC drops below this threshold and deassertion only after VCC exceeds it by sufficient margin plus hysteresis.

Does the MAX6865UK43D2L+T support active-high or active-low reset output?

The MAX6865UK43D2L+T features an active-high push-pull RESET output, as confirmed by its pin description (Pin 1 = RESET, active-high) and Selector Guide entry. It drives high (VOH ≥0.8×VCC) when not asserting reset and low (VOL ≤0.3V) during reset - eliminating need for external pullup resistors and simplifying interface to µP reset pins expecting active-high logic.

What is the watchdog timeout period for the MAX6865UK43D2L+T?

The MAX6865UK43D2L+T has a watchdog timeout period of 209s (typical), indicated by the "L" suffix in its part number. This long interval is designed for firmware that performs extended operations (e.g., sensor calibration, data encryption) without frequent WDI toggling. The watchdog timer clears on any rising or falling edge at the WDI pin (Pin 4), preventing false timeouts during valid software execution.

How does the MAX6865UK43D2L+T handle supply voltage transients?

The MAX6865UK43D2L+T is immune to short VCC transients up to 40µs duration when the overdrive is 100mV above its 4.300V reset threshold, as characterized in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph. This immunity prevents spurious resets caused by switching noise or load-step events in battery-powered systems, ensuring robust operation in electrically noisy portable medical environments.

Is the MAX6865UK43D2L+T compatible with 1.8V or 3.3V microcontrollers?

Yes, the MAX6865UK43D2L+T operates from 1.2V to 5.5V and interfaces seamlessly with 1.8V and 3.3V µPs: its push-pull RESET output delivers VOH ≥0.8×VCC at 500µA source current, meeting standard CMOS high-level input requirements. The MR input accepts VIH ≥0.7×VCC, and WDI tolerates VIH ≥0.7×VCC - ensuring reliable logic-level compatibility across common I/O voltages without level shifters.