Analog Devices Inc./Maxim Integrated MAX6865UK44D6L+T

Overview

The MAX6865UK44D6L+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 4.266V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It asserts active-low push-pull RESET during VCC brownout, MR assertion, or watchdog expiration-used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK44D6L+T datasheet, MAX6865UK44D6L+T pinout, MAX6865UK44D6L+T application, or MAX6865UK44D6L+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 voltage monitoring, a 209s watchdog timer (L-suffix), and manual reset logic in a single BiCMOS IC. Its internal 10kΩ MR pullup, glitch-rejecting MR input (200ns rejection), and WDI edge-triggered watchdog clearing ensure robust operation in noisy embedded systems.

The reset generator uses a precision bandgap reference and hysteresis (0.5% of VTH) to prevent chatter during slow VCC ramps. The watchdog timeout is temperature-stable (±15% over –40°C to +85°C), and the reset timeout (D6 = 600–1200ms) is factory-fixed-not pin-selectable like MAX6861–MAX6863.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3839G33DBVR and STM6315SDW13F, the MAX6865UK44D6L+T uniquely delivers 4.266V threshold accuracy, integrated 209s watchdog, and nanopower 170nA operation-enabling long-life, fail-safe supervision in medical and portable instrumentation where both precision voltage monitoring and firmware watchdogging are mandatory.

Availability

MAX6865UK44D6L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and low-power IoT edge nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6865UK44D6L+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 systems.

The MAX6854–MAX6869 family targets ultra-low-power microprocessor supervision in space-constrained, battery-operated equipment-emphasizing nanoscale ICC, wide VCC range, and integrated watchdog safety for mission-critical firmware.

FAQ

What is the exact reset threshold voltage of the MAX6865UK44D6L+T?

The MAX6865UK44D6L+T has a factory-trimmed reset threshold of 4.266V, with guaranteed limits of 4.193V (min) and 4.484V (max) over temperature. This value corresponds to the "44" suffix in the part number per Maxim's Threshold Suffix Guide, and is specified with ±2.5% tolerance at TA = –40°C to +85°C. The MAX6865UK44D6L+T uses this precise threshold to supervise 4.3V nominal rails in portable medical devices.

Does the MAX6865UK44D6L+T support active-high reset output?

No, the MAX6865UK44D6L+T provides only an active-low push-pull RESET output (Pin 1). Unlike the MAX6865's sibling MAX6865UK44D6L+T variant with "H" suffix or MAX6865UK44D6L+T's MAX6865 counterpart, this specific part does not offer active-high or open-drain configurations. Its RESET pin drives low during fault conditions and returns high after the 600–1200ms timeout, referenced directly to VCC.

What is the watchdog timeout behavior of the MAX6865UK44D6L+T?

The MAX6865UK44D6L+T features an L-suffix watchdog with a typical timeout of 209s (min 95s, max 487s). The internal timer resets on any rising or falling edge at WDI (Pin 4) and triggers RESET if WDI remains static beyond that period. During RESET assertion, the watchdog halts counting and resumes only after RESET deasserts-ensuring deterministic recovery in firmware hang scenarios. This behavior is confirmed in the MAX6865UK44D6L+T's Electrical Characteristics table.

Can the MAX6865UK44D6L+T operate below 1.2V?

No-the MAX6865UK44D6L+T specifies a minimum operating VCC of 1.2V per its Absolute Maximum Ratings and Electrical Characteristics tables. While RESET remains valid down to VCC = +1.1V (guaranteed), the device does not function correctly or guarantee specifications below 1.2V. Attempting operation at 1.1V may result in undefined timing, incomplete reset assertion, or failure to monitor VCC accurately. The MAX6865UK44D6L+T requires ≥1.2V for reliable supervision.

Is the MR input of the MAX6865UK44D6L+T compatible with 1.8V logic?

Yes-the MR input of the MAX6865UK44D6L+T accepts standard CMOS logic levels: VIH = 0.7 × VCC and VIL = 0.3 × VCC. At VCC = 1.8V, this translates to VIH ≥ 1.26V and VIL ≤ 0.54V, making it fully compatible with 1.8V I/O domains. The internal 10kΩ pullup ensures MR defaults high when unconnected, and the 1µs minimum pulse width and 200ns glitch rejection provide noise immunity in mixed-voltage systems. This specification is verified in the MAX6865UK44D6L+T's Electrical Characteristics section.