Analog Devices Inc./Maxim Integrated MAX6865UK25D2L+T

Overview

MAX6865UK25D2L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.5V reset threshold (±2.5%), 40ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK25D2L+T datasheet, MAX6865UK25D2L+T pinout, MAX6865UK25D2L+T application, or MAX6865UK25D2L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, pin-selectable reset output type, and compatibility with noisy low-power embedded systems requiring deterministic reset timing and watchdog supervision.

Technical Context

The MAX6865UK25D2L+T implements a dual-monitoring architecture: a precision voltage detector with hysteresis (0.5% of VTH) triggers reset on VCC drop below 2.5V, while a digital watchdog timer clears on any WDI edge and expires if WDI remains static >209s (typ). Its BiCMOS process enables stable operation across -40°C to +85°C with no external components required.

Reset assertion is synchronized to both VCC decay and MR deassertion, with a fixed 40ms minimum timeout (D2 option) after VCC recovery or MR release. The active-high push-pull RESET output drives directly to VCC, eliminating need for pull-up resistors, and maintains valid logic levels even as VCC falls to 1.1V.

Key Specifications

Pinout & Package

MAX6865UK25D2L+T is housed in a lead-free 5-pin SOT23-5 package (2.9mm × 1.6mm × 1.1mm), optimized for space-constrained portable designs. Pin 1 is RESET (active-high push-pull), Pin 2 is GND, Pin 3 is MR (active-low manual reset), Pin 4 is WDI (watchdog input), and Pin 5 is VCC (supply monitor input).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK25D2L+T and TPS3837K25DBVR, the MAX6865UK25D2L+T uniquely delivers active-high RESET, ultra-low 170nA current, and full watchdog supervision - making it optimal for safety-critical, battery-limited applications where both power efficiency and runtime reliability are mandatory.

Availability

MAX6865UK25D2L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, MP3 players, and industrial handheld terminals requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK25D2L+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 connectivity in demanding industrial, medical, and portable applications.

The MAX6865UK25D2L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power embedded systems needing reliable reset generation, manual reset capability, and watchdog supervision without compromising battery life.

FAQ

What is the exact reset threshold voltage of the MAX6865UK25D2L+T?

The MAX6865UK25D2L+T has a factory-trimmed reset threshold of 2.500V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "25" corresponds to 2.5V nominal. The device guarantees valid RESET assertion down to VCC = +1.1V, ensuring robust operation during deep brownout conditions.

Does the MAX6865UK25D2L+T require external components for basic operation?

No, the MAX6865UK25D2L+T operates autonomously with no external components required. Its internal voltage reference, timer circuitry, and 10kΩ MR pull-up eliminate need for external resistors or capacitors. A 0.1µF ceramic bypass capacitor on VCC is recommended for noise immunity but is not strictly required for functional operation per datasheet specifications.

How does the watchdog timer in the MAX6865UK25D2L+T respond to software activity?

The MAX6865UK25D2L+T watchdog timer clears on every rising or falling edge at the WDI pin and expires only if WDI remains static for >209s (typ). It does not require high-frequency toggling - a single edge within the timeout window suffices. The timer remains disabled during RESET assertion and resumes counting immediately upon RESET deassertion, enabling precise firmware hang detection without false triggers.

What is the function of Pin 1 (RESET) on the MAX6865UK25D2L+T?

Pin 1 of the MAX6865UK25D2L+T is an active-high push-pull RESET output. It drives high to VCC when reset is asserted (during VCC brownout, MR activation, or WDI timeout) and returns low when deasserted. Unlike open-drain variants, it requires no external pull-up resistor and maintains valid logic levels down to VCC = +1.1V - critical for fail-safe behavior in low-voltage systems.

Can the MAX6865UK25D2L+T be used in place of the MAX6864UK25D2L+T?

The MAX6865UK25D2L+T is not a direct replacement for the MAX6864UK25D2L+T due to opposite RESET polarity: MAX6865UK25D2L+T provides active-high RESET, while MAX6864UK25D2L+T provides active-low. Swapping them requires µP reset pin logic inversion or board-level redesign. Both share identical threshold (2.5V), timeout (40ms), and watchdog (209s), but RESET polarity must be verified against host system requirements.