Analog Devices Inc./Maxim Integrated MAX6865UK26D3S+T

Overview

The MAX6865UK26D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (2.625V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, ensuring reliable µP initialization in battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK26D3S+T datasheet, MAX6865UK26D3S+T pinout, MAX6865UK26D3S+T application, or MAX6865UK26D3S+T equivalent, key selection criteria include its 2.625V factory-trimmed threshold, 150ms minimum reset timeout, 209s watchdog period, guaranteed RESET validity down to VCC = +1.1V, and immunity to short VCC transients - all critical for low-power embedded system reliability and power-up sequencing.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a digital watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

The active-high push-pull RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V), while VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V), ensuring clean logic-level compatibility with modern µPs across 1.2V–5.5V supply range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK26D3S+T, MAX6864UK26D3S+T offers identical supervision performance but inverted reset polarity, while TPS3837K26DBVR trades off watchdog functionality and nanopower operation for lower unit cost - making MAX6865UK26D3S+T optimal for battery-powered medical and industrial IoT where both features and longevity are mandatory.

Availability

MAX6865UK26D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, wearable health trackers, and industrial sensor nodes requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK26D3S+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX68xx family delivers nanopower supervisory solutions optimized for battery-critical portable electronics, emphasizing ultra-low ICC, precise voltage thresholds, and integrated watchdog timers to ensure system-level reliability without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK26D3S+T?

The MAX6865UK26D3S+T has a factory-trimmed reset threshold of 2.625V, with guaranteed tolerance of ±2.5% over the full operating temperature range (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "26" corresponds to 2.625V nominal. The MAX6865UK26D3S+T maintains this precision without requiring external calibration or trimming components.

Does the MAX6865UK26D3S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK26D3S+T includes a watchdog timer with a typical timeout period of 209 seconds, denoted by the "L" suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, which specifies "S" for 3.3s and "L" for 209s. The MAX6865UK26D3S+T watchdog clears on any WDI edge and expires only if WDI remains static beyond this period, providing robust firmware hang detection.

What type of reset output does the MAX6865UK26D3S+T provide, and how is it configured?

The MAX6865UK26D3S+T provides an active-high push-pull RESET output, as confirmed in the Pin Description section for MAX6865 and the Selector Guide. Pin 1 drives high during reset assertion and low otherwise, referenced to VCC, eliminating the need for an external pullup resistor. This configuration is fixed per the part number and cannot be altered externally - the MAX6865UK26D3S+T does not support open-drain or active-low variants.

What is the minimum reset timeout period for the MAX6865UK26D3S+T, and how is it selected?

The MAX6865UK26D3S+T has a fixed minimum reset timeout period of 150ms, indicated by the "D3" suffix in the part number and confirmed in Table 4 (Reset Timeout Periods). Unlike the MAX6861–MAX6863 family, the MAX6865UK26D3S+T does not feature a CT pin for dynamic timeout selection - its 150ms timeout is factory-programmed and immutable. This duration ensures sufficient hold time for most 32-bit µPs to complete internal initialization sequences.

Is the MAX6865UK26D3S+T compatible with 1.8V and 3.3V supply rails?

Yes, the MAX6865UK26D3S+T operates across a VCC range of 1.2V to 5.5V and is fully specified at both 1.8V and 3.3V. Electrical Characteristics confirm supply current (170nA typ at 1.8V), RESET output voltage (VOH ≥ 0.8×VCC at ISOURCE = 500µA), and threshold accuracy across this range. The MAX6865UK26D3S+T is therefore suitable for mixed-voltage systems including ultra-low-power sensors and standard 3.3V microcontrollers.