Analog Devices Inc./Maxim Integrated MAX6865UK37D4L+T

Overview

The MAX6865UK37D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.7V 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 MAX6865UK37D4L+T datasheet, MAX6865UK37D4L+T pinout, MAX6865UK37D4L+T application, or MAX6865UK37D4L+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 monostable reset timeout generator (D4 = 1200ms min), and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). Its BiCMOS process enables stable operation across -40°C to +85°C with no external components required.

The MR input features internal 10kΩ pullup and 250ns MR-to-RESET delay; WDI accepts CMOS-level signals with 0.3×VCC/0.7×VCC thresholds and 20nA leakage. RESET output drives low to ≤0.3V at 1.2mA sink (VCC ≥ 2.38V) and high to ≥0.8×VCC at 500µA source - supporting direct interface to µP reset inputs without level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, 2.9mm × 1.6mm × 1.1mm, lead-free (RoHS-compliant), thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK37D4L+T, MAX6864UK37D4L+T offers identical supervision parameters but omits CT pin flexibility, while TPS3838K33DBVR provides basic reset at higher current and without watchdog - making MAX6865UK37D4L+T the sole choice for battery-critical systems needing both long-interval watchdog and deterministic 1200ms reset hold.

Availability

MAX6865UK37D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, handheld diagnostic scanners, and wearable drug infusion pumps requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK37D4L+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, with emphasis on low-power, high-reliability solutions for medical and industrial markets.

The MAX6865UK37D4L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-current battery-powered systems requiring guaranteed reset behavior, watchdog supervision, and wide-temperature operation without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK37D4L+T?

The MAX6865UK37D4L+T has a factory-trimmed reset threshold of 3.700V with ±2.5% tolerance (3.608V to 3.793V), corresponding to the "37" suffix per Maxim's Threshold Suffix Guide. This value is guaranteed over -40°C to +85°C and applies to VCC falling conditions; hysteresis is 0.5% of VTH.

Does the MAX6865UK37D4L+T require external components for basic operation?

No, the MAX6865UK37D4L+T operates autonomously with no external components required. A 0.1µF ceramic capacitor from VCC to GND is recommended for noise immunity but not mandatory for functionality. The MR input has an internal 10kΩ pullup, and RESET is push-pull active-low - eliminating need for external pullups or timing resistors.

How does the watchdog timer in the MAX6865UK37D4L+T respond to software activity?

The MAX6865UK37D4L+T watchdog timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static for ≥209s (typ). It does not require periodic high-low toggling - a single edge within the timeout period suffices. The timer pauses while RESET is asserted and resumes counting immediately upon deassertion.

What is the minimum VCC voltage at which MAX6865UK37D4L+T guarantees valid RESET output?

The MAX6865UK37D4L+T guarantees RESET output validity down to VCC = +1.1V, meaning the RESET signal remains electrically well-defined (low/high states meet VOH/VOL specs) even as supply voltage collapses. Below 1.1V, RESET behavior is not specified - consistent with most µPs ceasing operation below this rail.

Can the MAX6865UK37D4L+T be used in systems with 1.2V logic supplies?

Yes, the MAX6865UK37D4L+T operates from VCC = 1.2V to 5.5V and specifies electrical performance across this full range. At 1.2V, supply current is 7µA (typ) when RESET is asserted, and RESET output meets VOL ≤0.3V at ISINK = 50µA - enabling direct interface to 1.2V I/O domains without level shifters.