Analog Devices Inc./Maxim Integrated MAX6865UK28D5S+T

Overview

The MAX6865UK28D5S+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-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 450ms min after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK28D5S+T datasheet, MAX6865UK28D5S+T pinout, MAX6865UK28D5S+T application, or MAX6865UK28D5S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with 1.2V–5.5V supply rails in space-constrained portable systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature, a digital watchdog timer that clears on any WDI edge (rising or falling), and a fixed 450ms minimum reset timeout period (D5 option). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable direct switch interfacing 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); VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V). Watchdog timing is factory-trimmed to 3.3s typical with ±50% variation over -40°C to +85°C.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK28D5S+T, the MAX6865UK28D5S+T provides native active-high reset signaling, eliminating need for external inverters; versus TPS3837K28QDBVR, it adds critical watchdog protection at 1/10th the supply current - essential for long-life battery applications.

Availability

MAX6865UK28D5S+T is available at Aetrix Electronics and suitable for glucose monitoring systems, patient vital sign monitors, industrial handheld scanners, and wireless sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK28D5S+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 was designed specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer electronics, emphasizing nanoscale current consumption and robust reset timing under voltage stress.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D5S+T?

The MAX6865UK28D5S+T has a factory-trimmed reset threshold of +2.800V, with ±2.5% tolerance over -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 in the MAX6865UK28D5S+T application space.

Does the MAX6865UK28D5S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK28D5S+T includes a watchdog timer with a typical timeout of 3.3 seconds (S suffix), as specified in Table 3 (Watchdog Timeout). The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period. This feature is integral to the MAX6865UK28D5S+T's role in detecting firmware hangs in portable medical devices.

What type of reset output does the MAX6865UK28D5S+T provide?

The MAX6865UK28D5S+T provides an active-high push-pull RESET output (pin 1), which drives high during reset assertion and low when deasserted. Unlike open-drain variants, it requires no external pullup resistor. Its VOH ≥ 0.8×VCC (at ISOURCE = 500µA, VCC ≥ 2.38V) and VOL ≤ 0.3V (at ISINK = 1.2mA, VCC ≥ 2.38V) ensure clean logic-level compatibility with modern µPs - a defining characteristic of the MAX6865UK28D5S+T.

What is the reset timeout period for the MAX6865UK28D5S+T?

The MAX6865UK28D5S+T uses the D5 reset timeout option, providing a minimum reset pulse width of 450ms (typical 450ms, max 600ms) after VCC rises above the 2.800V threshold or MR deasserts. This value is encoded in the part number suffix "D5" per Table 4 (Reset Timeout Periods) and ensures sufficient time for microprocessor initialization before firmware execution resumes in the MAX6865UK28D5S+T design context.

Is the MAX6865UK28D5S+T compatible with 1.8V and 3.3V supply rails?

Yes, the MAX6865UK28D5S+T operates across a 1.2V to 5.5V VCC range and is fully specified at 1.8V and 3.3V. Its 170nA typical supply current, guaranteed reset validity down to VCC = +1.1V, and logic-compatible MR/WDI inputs make it interoperable with both 1.8V and 3.3V µPs without level shifters - a key advantage in mixed-voltage portable systems using the MAX6865UK28D5S+T.