Analog Devices Inc./Maxim Integrated MAX6865UK27D3L+T

Overview

The MAX6865UK27D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (reset threshold = +2.700V), manual reset input (MR), and watchdog timer (timeout = 209s typ) 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 300ms min after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK27D3L+T datasheet, MAX6865UK27D3L+T pinout, MAX6865UK27D3L+T application, or MAX6865UK27D3L+T equivalent, key selection criteria include its 2.7V factory-trimmed reset threshold, 209s watchdog timeout (L-suffix), 300ms reset timeout (D3), active-high push-pull output, and guaranteed reset validity down to VCC = +1.1V in -40°C to +85°C industrial temperature range.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature, coupled with a digitally controlled watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The internal reset timeout generator uses RC-based timing with factory trimming for 300ms minimum assertion period.

Its active-high push-pull RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V), while MR features 10kΩ internal pullup and 1µs minimum pulse width support. Immunity to short VCC transients (<40µs at 100mV overdrive) ensures robust operation in noisy portable systems.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK27D3S+T and TPS3837K27DBVR, the MAX6865UK27D3L+T uniquely combines long 209s watchdog supervision, active-high push-pull output, and nanopower operation - making it optimal for battery-constrained medical devices requiring both voltage and software-execution monitoring without layout changes.

Availability

MAX6865UK27D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and wearable health trackers requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK27D3L+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 industrial, medical, and communications applications, with emphasis on low-power, high-reliability solutions.

The MAX6865UK27D3L+T belongs to the MAX68xx nanopower µP supervisory family, engineered specifically for battery-operated medical and portable electronics where ultra-low ICC, guaranteed reset validity at low VCC, and integrated watchdog supervision are critical.

FAQ

What is the exact reset threshold voltage of the MAX6865UK27D3L+T?

The MAX6865UK27D3L+T has a factory-trimmed reset threshold of +2.700V, with ±2.5% accuracy over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "27" corresponds to 2.700V nominal. The device guarantees reset assertion when VCC falls below this threshold and deassertion only after VCC exceeds it by ≥150mV plus timeout delay.

Does the MAX6865UK27D3L+T include a watchdog timer, and what is its timeout duration?

Yes, the MAX6865UK27D3L+T includes a watchdog timer with a typical timeout duration of 209 seconds, indicated by the "L" suffix in the part number. This long timeout is optimized for low-duty-cycle firmware in medical devices. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond the timeout window - ensuring supervision of software execution without excessive interrupt overhead.

What type of reset output does the MAX6865UK27D3L+T provide, and how is it configured?

The MAX6865UK27D3L+T provides an active-high push-pull RESET output (Pin 1), as confirmed in the MAX6865 pin description and Selector Guide. This output drives high (VOH ≥ 0.8×VCC) when reset is asserted and low when deasserted - eliminating the need for an external pullup resistor. It is directly compatible with µP reset inputs expecting active-high logic, such as those on ARM Cortex-M series MCUs.

What is the reset timeout period for the MAX6865UK27D3L+T, and how is it selected?

The MAX6865UK27D3L+T has a fixed minimum reset timeout period of 300ms, denoted by the "D3" suffix. This value is factory-set and non-adjustable; it defines the minimum duration RESET remains asserted after VCC rises above the threshold or MR is released. The timeout is implemented with internal trimmed RC timing and is guaranteed across temperature and voltage per Table 4 (Reset Timeout Periods) in the datasheet.

Is the MAX6865UK27D3L+T compatible with 1.8V or 2.5V supply rails, and what is its minimum operating voltage?

Yes, the MAX6865UK27D3L+T operates from VCC = 1.2V to 5.5V and is fully specified at 1.8V and 2.5V. Its reset output remains valid down to VCC = +1.1V, ensuring reliable assertion during deep brownout conditions. At 1.8V supply, typical supply current is 170nA, and RESET output meets VOH ≥ 0.8×VCC at 200µA source current - making it suitable for modern low-voltage microcontrollers and sensors.