Analog Devices Inc./Maxim Integrated MAX6865UK27D3S+T

Overview

The MAX6865UK27D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (reset threshold = +2.700V), 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, ensuring reliable µP initialization in battery-powered medical and portable systems.

For engineers reviewing the MAX6865UK27D3S+T datasheet, MAX6865UK27D3S+T pinout, MAX6865UK27D3S+T application, or MAX6865UK27D3S+T equivalent, key selection criteria include its factory-trimmed 2.700V reset threshold, 3.3s watchdog timeout, 150ms minimum reset timeout, guaranteed RESET validity down to VCC = +1.1V, and compatibility with 1.2V–5.5V supply rails.

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 provides fixed 150ms (min) assertion after VCC recovery or MR release.

The MAX6865UK27D3S+T uses BiCMOS process technology (2848 transistors) to achieve 170nA supply current at 2.5V/25°C while maintaining immunity to VCC transients ≤40µs at 100mV overdrive. Its push-pull active-high RESET output drives directly to VCC with VOH ≥0.8×VCC at ISOURCE = 500µA and VOL ≤0.3V at ISINK = 1.2mA.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK27D3S+T, the MAX6865UK27D3S+T adds no functional difference but belongs to the same pin-compatible family; versus TPS3836K27DBVR, it delivers 93% lower supply current and integrated watchdog-critical for energy-constrained, safety-critical portable designs.

Availability

MAX6865UK27D3S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and wearable health trackers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK27D3S+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 markets.

The MAX68xx family was designed specifically for ultra-low-power microprocessor supervision in space- and energy-constrained portable electronics, emphasizing nanoscale ICC, factory-trimmed thresholds, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK27D3S+T?

The MAX6865UK27D3S+T has a factory-trimmed reset threshold of +2.700V, 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 "27" corresponds to 2.700V nominal. The MAX6865UK27D3S+T maintains this accuracy without external calibration components.

Does the MAX6865UK27D3S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK27D3S+T integrates a watchdog timer with a typical timeout period of 3.3 seconds, denoted by the "S" suffix in the part number. This timeout is specified in Table 3 (Watchdog Timeout) and is valid across temperature; the timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this interval. The MAX6865UK27D3S+T uses this to detect µP firmware hangs.

What type of RESET output does the MAX6865UK27D3S+T provide, and how is it configured?

The MAX6865UK27D3S+T provides an active-high push-pull RESET output (Pin 1), as confirmed in the MAX6865 pin description and Selector Guide. It drives directly to VCC with VOH ≥0.8×VCC and VOL ≤0.3V under load, eliminating the need for an external pullup resistor. This configuration is fixed for the MAX6865UK27D3S+T and differs from open-drain or active-low variants in the same family.

What is the minimum reset timeout period for the MAX6865UK27D3S+T, and how is it selected?

The MAX6865UK27D3S+T has a fixed minimum reset timeout period of 150ms, indicated by the "D3" suffix in the part number per Table 4 (Reset Timeout Periods). Unlike MAX6861–MAX6863 variants, it does not feature a CT pin for dynamic timeout selection-the 150ms value is factory-programmed and immutable. This ensures predictable reset hold time for µP initialization in the MAX6865UK27D3S+T.

Is the MAX6865UK27D3S+T compatible with 1.8V microcontrollers, and what is its lowest valid VCC?

Yes, the MAX6865UK27D3S+T operates across 1.2V to 5.5V and is fully compatible with 1.8V µCs. Its RESET output remains valid down to VCC = +1.1V, guaranteeing deterministic behavior during brownout-critical for 1.8V systems where supply collapse may occur below nominal rail. The MAX6865UK27D3S+T draws only 170nA at 1.8V, preserving battery life in such applications.