Analog Devices Inc./Maxim Integrated MAX6865UK28D2S+T

Overview

The MAX6865UK28D2S+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, maintaining reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK28D2S+T datasheet, MAX6865UK28D2S+T pinout, MAX6865UK28D2S+T application, or MAX6865UK28D2S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, fixed 40ms reset timeout, and compatibility with 1.2V–5.5V supply rails in space-constrained portable systems.

Technical Context

This device integrates a precision voltage comparator with ±2.5% threshold accuracy, a monostable reset timeout generator, and a digital watchdog timer that clears on any WDI edge (rising or falling). Its internal 10kΩ MR pullup and glitch rejection (200ns) eliminate external components while ensuring robust operation in noisy environments.

The MAX6865UK28D2S+T uses BiCMOS process technology (2848 transistors) to achieve nanoscale quiescent current without sacrificing timing integrity: reset delay (tRD) is 40µs max, MR-to-reset delay (tMRD) is 250ns, and WDI pulse width acceptance is ≥150ns - all specified across –40°C to +85°C.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, RoHS-compliant), footprint compatible with industry-standard 5-pin SOT-23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK28D2S+T, MAX6326UR29+T offers simpler supervision but no fault-detection intelligence, while TPS3836K33DBVR trades 10× higher current for broader vendor support - making MAX6865UK28D2S+T optimal for long-life, safety-critical portable medical devices requiring both voltage and software monitoring.

Availability

MAX6865UK28D2S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and low-power IoT edge nodes requiring stable component supply with full lifecycle traceability.

Supply support for MAX6865UK28D2S+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 was engineered specifically for ultra-low-power microprocessor supervision in space- and energy-constrained portable electronics, emphasizing nanoscale ICC, wide VCC range, and integrated watchdog functionality.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D2S+T?

The MAX6865UK28D2S+T has a factory-trimmed reset threshold of +2.800V, with ±2.5% tolerance 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 "28" corresponds to 2.800V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for deep brownout scenarios.

Does the MAX6865UK28D2S+T support active-high reset output?

No, the MAX6865UK28D2S+T provides only an active-low push-pull RESET output (Pin 1). Unlike variants such as MAX6865UK28D2S+T's sibling MAX6865UK28D2S+T (which does not exist), this specific part number is configured for active-low operation per its ordering code and functional diagram. The datasheet Pin Description section explicitly lists Pin 1 as "Active-Low Push-Pull Reset Output" for MAX6864/MAX6865/MAX6866 devices.

What is the watchdog timeout period for the MAX6865UK28D2S+T?

The MAX6865UK28D2S+T features a watchdog timeout period of 3.3s typical (minimum 1.5s, maximum 7.75s), denoted by the "S" suffix in its part number. This is verified in Table 3 (Watchdog Timeout) and confirmed in the Ordering Information section, where "S" maps to the short watchdog interval. The timer resets on any WDI edge and expires only if no transition occurs within the timeout window.

Can the MAX6865UK28D2S+T operate from a 1.2V supply?

Yes, the MAX6865UK28D2S+T operates across a VCC range of 1.2V to 5.5V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. At 1.2V, it maintains guaranteed reset functionality down to VCC = +1.1V and draws only 170nA typical supply current - enabling use in single-cell alkaline or low-voltage LiFePO₄ systems where traditional supervisors fail.

Is the MR input of the MAX6865UK28D2S+T internally pulled up?

Yes, the MR input (Pin 3) of the MAX6865UK28D2S+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description and Applications Information sections. This eliminates the need for an external pullup, simplifies PCB layout, and allows direct connection to CMOS logic or open-drain drivers. The datasheet specifies MR minimum pulse width as 1µs and glitch rejection as 200ns.