Analog Devices Inc./Maxim Integrated MAX6865UK23D3L+T

Overview

The MAX6865UK23D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (V_TH = 2.23 V), manual reset input (MR), and watchdog timer (t_WD = 209 s typ) with ultra-low 170 nA typical supply current. It asserts an active-low push-pull RESET output during V_CC brownout, MR assertion, or watchdog timeout - used in battery-powered glucose monitors and portable medical devices requiring guaranteed reset validity down to V_CC = 1.1 V.

For engineers reviewing the MAX6865UK23D3L+T datasheet, MAX6865UK23D3L+T pinout, MAX6865UK23D3L+T application, or MAX6865UK23D3L+T equivalent, key selection criteria include factory-trimmed 2.23 V reset threshold, 150 ms minimum reset timeout, 209 s watchdog period, and compatibility with noisy low-voltage systems operating from 1.2 V to 5.5 V.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature, coupled with a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 209 s (typ). The internal reset timeout generator provides fixed 150 ms minimum assertion after V_CC recovery or MR release.

Its push-pull active-low RESET output drives directly into µP reset inputs without external pullup, sinking ≤0.3 V at 1.2 mA (V_CC ≥ 2.38 V), while MR features 10 kΩ internal pullup and 1 µs minimum pulse width immunity. The circuit guarantees valid reset operation down to V_CC = 1.1 V and rejects transients ≤40 µs at 100 mV overdrive.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9 mm × 1.6 mm footprint with 0.95 mm height - optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK23D3L+T, the MAX6865UK23D3L+T offers identical core supervision but adds CT pin support for future design flexibility; versus TPS3836K33DBVR, it delivers 170 nA operation and 209 s watchdog - essential for modern battery-critical medical wearables.

Availability

MAX6865UK23D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient loggers, handheld diagnostics, and wearable biosensors requiring stable component supply across industrial temperature ranges and long-lifecycle production programs.

Supply support for MAX6865UK23D3L+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 - emphasizing reliability, low power, and high integration for demanding industrial and medical systems.

The MAX6854–MAX6869 family was engineered specifically for nanopower microprocessor supervision in battery-constrained portable medical and IoT devices - delivering guaranteed reset behavior, watchdog safety, and minimal bill-of-materials overhead.

FAQ

What is the exact reset threshold voltage of the MAX6865UK23D3L+T?

The MAX6865UK23D3L+T has a factory-trimmed reset threshold voltage of 2.23 V, with ±2.5% tolerance over the -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix '23' corresponds to V_TH = 2.23 V. The MAX6865UK23D3L+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK23D3L+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK23D3L+T includes a watchdog timer with a typical timeout period of 209 seconds, denoted by the 'L' suffix in the part number. This long-duration watchdog is designed for applications where firmware execution cycles are infrequent - such as periodic sensor sampling in medical devices. The timer resets on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond the timeout window.

What is the reset timeout period of the MAX6865UK23D3L+T, and is it configurable?

The MAX6865UK23D3L+T has a fixed minimum reset timeout period of 150 ms, indicated by the 'D3' suffix. Unlike the MAX6861–MAX6863 variants, the MAX6865UK23D3L+T does not feature a CT pin for pin-selectable timeout options - its 150 ms timeout is factory-set and non-adjustable. This duration ensures sufficient hold time for reliable microprocessor initialization after power recovery or manual reset release.

What package type and pin configuration does the MAX6865UK23D3L+T use?

The MAX6865UK23D3L+T uses a 5-pin SOT23-5 package with lead-free finish (+T suffix). Pin 1 is RESET (active-low push-pull), Pin 2 is GND, Pin 3 is MR (active-low manual reset), Pin 4 is WDI (watchdog input), and Pin 5 is V_CC. This configuration matches the MAX6864–MAX6866 series and is documented in the "MAX6864/MAX6865/MAX6866 Pin Description" section of the datasheet.

How does the MAX6865UK23D3L+T ensure reliable operation at low supply voltages?

The MAX6865UK23D3L+T guarantees valid RESET output down to V_CC = 1.1 V - critical for detecting brownout conditions before system failure. Its 170 nA typical supply current allows operation from weak or aging batteries, and its internal voltage reference remains stable across the full 1.2 V to 5.5 V operating range. This behavior is verified in the Electrical Characteristics table under "VCC Reset Threshold" and "Guaranteed Reset Valid to VCC = +1.1V" feature.