Analog Devices Inc./Maxim Integrated MAX6865UK21D6S+T

Overview

The MAX6865UK21D6S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functions. It asserts an active-low push-pull RESET output when VCC drops below 2.100V (factory-trimmed threshold), MR is pulled low, or the watchdog times out after 3.3s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) at 2.5V and guarantees valid reset down to VCC = +1.1V.

For engineers reviewing the MAX6865UK21D6S+T datasheet, MAX6865UK21D6S+T pinout, MAX6865UK21D6S+T application, or MAX6865UK21D6S+T equivalent, key selection criteria include its 2.100V reset threshold, 600–1200ms reset timeout (D6 option), 3.3s watchdog period (S suffix), push-pull active-high RESET output, and compatibility with battery-powered medical and portable electronics requiring guaranteed reset assertion below 1.2V supply.

Technical Context

The MAX6865UK21D6S+T implements a dual-trigger reset architecture: one path monitors VCC against a precision ±2.5% factory-trimmed 2.100V threshold, while a second path responds to MR assertion or WDI inactivity exceeding 3.3s (typ). Its internal watchdog timer clears on any WDI edge (rising or falling) and remains disabled during RESET assertion.

This device uses BiCMOS process technology (2848 transistors) to achieve 170nA typical supply current and operates across –40°C to +85°C. The reset timeout is fixed at 600–1200ms (D6), and the push-pull active-high RESET output drives high with VOH ≥ 0.8×VCC (ISOURCE = 500µA) and low with VOL ≤ 0.3V (ISINK = 1.2mA).

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK21D6S+T, the MAX6865UK21D6S+T provides native active-high reset signaling, eliminating level translation. Against TPS3837K21DBVR, it delivers 99% lower supply current and integrated watchdog - critical for multi-year battery life and functional safety compliance.

Availability

MAX6865UK21D6S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and smart pagers requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK21D6S+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 consumer markets.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and handheld devices, emphasizing nanoscale current consumption and robust reset timing under brownout.

FAQ

What is the exact reset threshold voltage of the MAX6865UK21D6S+T?

The MAX6865UK21D6S+T has a factory-trimmed reset threshold voltage of +2.100V, with a tolerance of ±2.5% over the –40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "21" corresponds to 2.100V. The MAX6865UK21D6S+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK21D6S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK21D6S+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. The timer resets on any WDI edge and expires only if WDI remains static longer than 3.3s (typ), triggering a full reset cycle with the D6 timeout period.

What type of RESET output does the MAX6865UK21D6S+T provide, and how is it configured?

The MAX6865UK21D6S+T provides a push-pull active-high RESET output, as confirmed by the Selector Guide and Pin Description tables. Pin 1 is labeled RESET and functions as an active-high driver referenced to VCC - it outputs high during reset assertion and low otherwise. No external pullup resistor is needed, distinguishing it from open-drain variants like the MAX6866.

What is the reset timeout period for the MAX6865UK21D6S+T, and how is it selected?

The MAX6865UK21D6S+T has a fixed reset timeout period of 600–1200ms, designated by the "D6" suffix per Table 4 (Reset Timeout Periods). This timeout begins after VCC rises above the 2.100V threshold and MR deasserts, and is implemented entirely within the IC with no external timing components. The D6 option ensures sufficient hold time for complex µP initialization sequences.

Is the MAX6865UK21D6S+T compatible with 1.8V or 3.3V microcontrollers?

Yes, the MAX6865UK21D6S+T is fully compatible with both 1.8V and 3.3V microcontrollers. Its push-pull active-high RESET output delivers VOH ≥ 0.8×VCC (with ISOURCE = 500µA) and VOL ≤ 0.3V (with ISINK = 1.2mA), meeting standard CMOS logic thresholds across its 1.2V–5.5V operating range. The MR input also accepts 0.3×VCC/0.7×VCC logic levels, ensuring interoperability.