Analog Devices Inc./Maxim Integrated MAX6865UK24D2S+T

Overview

The MAX6865UK24D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (2.4V ±2.5% reset threshold), manual reset input (MR), and watchdog timer (3.3s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, maintaining reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK24D2S+T datasheet, MAX6865UK24D2S+T pinout, MAX6865UK24D2S+T application, or MAX6865UK24D2S+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, pin-selectable reset timeout options, and compatibility with noisy low-power embedded systems requiring deterministic fault recovery.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% hysteresis, a digital watchdog timer cleared on WDI edge transitions, and a dedicated MR input with 10kΩ internal pullup and 250ns MR-to-reset delay. The reset timeout generator uses an internal RC oscillator calibrated for stable operation across -40°C to +85°C.

The MAX6865UK24D2S+T features a push-pull active-high RESET output referenced to VCC, enabling direct interface with µP reset inputs without external pullups. Its watchdog function requires no software configuration - it triggers reset if WDI remains static beyond 3.3s (typ), supporting fail-safe recovery in unattended medical instrumentation.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK24D2S+T, the MAX6864UK24D2S+T offers identical supervision parameters but lacks CT pin flexibility, while the TPS3836K24DBVR omits watchdog capability and consumes ~9x more current - making MAX6865UK24D2S+T the optimal choice for ultra-low-power, watchdog-requiring medical edge devices.

Availability

MAX6865UK24D2S+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and low-power IoT sensor nodes requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK24D2S+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 demanding industrial, medical, and communications applications.

The MAX6865UK24D2S+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for battery-critical medical and portable electronics where sub-µA quiescent current and deterministic fault recovery are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK24D2S+T?

The MAX6865UK24D2S+T has a factory-trimmed reset threshold of 2.400V 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 "24" corresponds to 2.400V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for applications with significant supply droop.

Does the MAX6865UK24D2S+T support both manual reset and watchdog functions simultaneously?

Yes, the MAX6865UK24D2S+T fully supports concurrent manual reset and watchdog operation. Its MR pin initiates reset when pulled low, while the WDI pin monitors µP activity - either condition independently triggers the RESET output. The internal logic ensures reset remains asserted for the full 40ms timeout period after VCC recovery, MR deassertion, or watchdog expiration, as verified in the Functional Diagram (Figure 1) and timing specifications.

What is the watchdog timeout period for the MAX6865UK24D2S+T, and how is it selected?

The MAX6865UK24D2S+T uses the "S" watchdog suffix, providing a typical timeout period of 3.3 seconds (min 1.5s, max 7.75s). This value is fixed per ordering code and cannot be adjusted externally - unlike CT-pin variants, the MAX6865UK24D2S+T does not support pin-selectable watchdog periods. The timeout is guaranteed over temperature and supply voltage per Table 3 in the datasheet.

What package type and lead finish does the MAX6865UK24D2S+T use?

The MAX6865UK24D2S+T is supplied in a 5-pin SOT23 package with lead-free (RoHS-compliant) finish, indicated by the "+T" suffix in the part number. This matches the standard SOT-23-5 footprint used across the MAX6854–MAX6869 family and is compatible with reflow soldering processes per JEDEC J-STD-020. Pin configuration follows the MAX6864–MAX6866 layout (RESET on pin 1, GND on pin 2, MR on pin 3, WDI on pin 4, VCC on pin 5).

How does the MAX6865UK24D2S+T handle short VCC transients, and what is its immunity level?

The MAX6865UK24D2S+T is immune to VCC transients ≤40µs in duration when the overdrive is 100mV above the 2.4V threshold, as shown in Figure MAX684 toc05. This transient immunity prevents false resets caused by switching noise or coupling in compact PCB layouts. The device achieves this via internal filtering and hysteresis (0.5% of VTH), ensuring reliable operation in electrically noisy medical equipment without requiring additional external filtering.