Analog Devices Inc./Maxim Integrated MAX6865UK34D4L+T

Overview

The MAX6865UK34D4L+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 3.4V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout (L-suffix). It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout-used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK34D4L+T datasheet, MAX6865UK34D4L+T pinout, MAX6865UK34D4L+T application, or MAX6865UK34D4L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, watchdog pulse detection as short as 150ns, and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a glitch-immune manual reset input with 10kΩ internal pullup and 250ns MR-to-reset delay, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The reset assertion logic combines ORed conditions-VCC < VTH, MR low, or WDI timeout-with a fixed 1200ms deassertion hold time after recovery.

Its BiCMOS process enables operation across -40°C to +85°C with supply current stable below 200nA over temperature (170nA typ at +25°C) and guaranteed reset functionality even as VCC drops to 1.1V-critical for deep-brownout detection in single-cell Li-ion or coin-cell systems.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), footprint compatible with industry-standard 5-lead SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK34D4L+T and TPS3838K33DBVR, the MAX6865UK34D4L+T uniquely delivers MR capability alongside 209s watchdog and 170nA ICC-enabling field-serviceable, long-life, fault-resilient designs where both manual intervention and firmware hang detection are mandatory.

Availability

MAX6865UK34D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart wearable sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK34D4L+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 and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical systems-emphasizing nanoscale ICC, wide VCC range, and integrated watchdog/manual reset without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK34D4L+T?

The MAX6865UK34D4L+T has a factory-trimmed reset threshold of 3.4V with ±2.5% tolerance over -40°C to +85°C, corresponding to the "34" suffix per Maxim's Threshold Suffix Guide (Table 2). This value is laser-trimmed during production and requires no external calibration. The MAX6865UK34D4L+T guarantees reset assertion when VCC falls below this threshold and deassertion only after VCC exceeds it plus hysteresis (0.5% of VTH).

Does the MAX6865UK34D4L+T require external components for basic operation?

No, the MAX6865UK34D4L+T operates autonomously with no external components required. Its 3.4V threshold and 1200ms reset timeout are factory-programmed; only a 0.1µF ceramic capacitor from VCC to GND is recommended for noise suppression. The MR input includes a 10kΩ internal pullup, and the push-pull RESET output drives µP reset pins directly-eliminating external resistors, capacitors, or trimming networks needed by discrete supervisor solutions.

How does the watchdog timer in the MAX6865UK34D4L+T function, and what is its timeout value?

The MAX6865UK34D4L+T watchdog timer expires if the WDI input remains static (high or low) for longer than 209s (typical), per the "L" suffix in the part number. It clears on any rising or falling edge at WDI and is disabled during RESET assertion. The timer supports pulse widths as short as 150ns, making it robust against noise while enabling flexible firmware integration-e.g., toggling WDI at subroutine entry/exit. This behavior is fully specified in the Electrical Characteristics table under "Watchdog Timeout Period".

What is the minimum supply voltage at which the MAX6865UK34D4L+T guarantees valid RESET output?

The MAX6865UK34D4L+T guarantees RESET output validity down to VCC = +1.1V, as explicitly stated in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, RESET may become indeterminate-but since most microprocessors cease functional operation below 1.1V, this specification ensures deterministic reset behavior across the entire usable supply range. This feature is critical for battery-powered systems where VCC decays gradually during end-of-life.

Is the MAX6865UK34D4L+T pin-compatible with other devices in the MAX68xx family?

Yes, the MAX6865UK34D4L+T shares the identical 5-pin SOT23-5 pinout with all MAX6864–MAX6869 variants (e.g., MAX6864, MAX6866), including RESET (pin 1), GND (pin 2), MR (pin 3), WDI (pin 4), and VCC (pin 5). This allows direct substitution within the same watchdog-enabled subgroup, provided the reset threshold, timeout, and output polarity match system requirements. Pin compatibility is confirmed in the "Pin Configurations" section (page 15) and Selector Guide (page 16) of the datasheet.