Analog Devices Inc./Maxim Integrated MAX6865UK28D4S+T

Overview

The MAX6865UK28D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (reset threshold = +2.800V), manual reset input (MR), and watchdog timer (timeout = 3.3s typ) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output 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 MAX6865UK28D4S+T datasheet, MAX6865UK28D4S+T pinout, MAX6865UK28D4S+T application, or MAX6865UK28D4S+T equivalent, key selection criteria include its factory-trimmed 2.800V reset threshold, 1200ms minimum reset timeout (D4), S-suffix 3.3s watchdog period, guaranteed RESET validity down to VCC = +1.1V, and immunity to sub-40µs VCC transients.

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 3.3s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator, delivering 1200ms (min) assertion after VCC recovery or MR release.

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection; RESET output provides push-pull active-low drive with VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA - enabling direct interfacing with 1.8V–5.5V µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

5-pin SOT23 package (2.9mm × 1.6mm × 1.1mm height), lead-free per RoHS, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK28D4S+T, the MAX6865UK28D4S+T adds WDI functionality without increasing ICC; versus TPS3836K28DBVR, it delivers 7× lower supply current and integrated watchdog - critical for battery longevity and firmware reliability in portable medical electronics.

Availability

MAX6865UK28D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, smart wearables, and industrial handheld terminals requiring stable component supply with long-term lifecycle assurance.

Supply support for MAX6865UK28D4S+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 in industrial, medical, and communications markets.

The MAX6854–MAX6869 family targets ultra-low-power microprocessor supervision in battery-constrained systems, emphasizing nanopower operation, factory-trimmed accuracy, and integrated watchdog functionality for safety-critical firmware monitoring.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D4S+T?

The MAX6865UK28D4S+T has a factory-trimmed reset threshold of +2.800V, with guaranteed tolerance of ±2.5% 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 '28' corresponds to 2.800V nominal. The MAX6865UK28D4S+T maintains this accuracy without external calibration components.

Does the MAX6865UK28D4S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK28D4S+T includes a watchdog timer with a typical timeout period of 3.3 seconds, indicated by the 'S' suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, which specifies 'S' = 1.5s/3.3s/7.75s (min/typ/max). The MAX6865UK28D4S+T watchdog clears on any WDI edge and expires only if WDI remains static beyond this period.

What reset timeout period is implemented in the MAX6865UK28D4S+T?

The MAX6865UK28D4S+T implements a 1200ms minimum reset timeout period, denoted by the 'D4' suffix. As specified in Table 4 (Reset Timeout Periods), D4 corresponds to 1200ms (min)/1800ms (typ)/2400ms (max). This timeout begins after VCC rises above the 2.800V threshold or MR is deasserted, ensuring sufficient µP initialization time before release.

What is the supply current consumption of the MAX6865UK28D4S+T under typical conditions?

The MAX6865UK28D4S+T draws 170nA typical supply current (ICC) when VCC > VTH and the reset output is deasserted, measured at VCC = 1.8V, TA = +25°C. This ultra-low value is documented in the Electrical Characteristics table and enables multi-year operation on coin-cell batteries. The MAX6865UK28D4S+T maintains sub-µA ICC across its full 1.2V–5.5V VCC range.

What package type and pin configuration does the MAX6865UK28D4S+T use?

The MAX6865UK28D4S+T uses a 5-pin SOT23 package (2.9mm × 1.6mm) with pin 1 = RESET (active-low push-pull), pin 2 = GND, pin 3 = MR, pin 4 = WDI, and pin 5 = VCC. This configuration is explicitly shown in the "MAX6864/MAX6865/MAX6866 Pin Description" section and the Pin Configurations diagram for MAX6865.