Analog Devices Inc./Maxim Integrated MAX6865UK22D2S+T

Overview

The MAX6865UK22D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (2.235V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK22D2S+T datasheet, MAX6865UK22D2S+T pinout, MAX6865UK22D2S+T application, or MAX6865UK22D2S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset timeout options, and compatibility with low-voltage µP systems requiring long battery life and robust fault recovery.

Technical Context

This device implements a dual-trigger reset architecture: one path responds to VCC falling below 2.235V ±2.5%, another to MR assertion, and a third to WDI inactivity exceeding 209s (typ). The internal watchdog timer clears on any WDI edge (rising or falling) and remains disabled while RESET is asserted.

The push-pull active-high RESET output is referenced to VCC and delivers VOH ≥0.8×VCC (ISOURCE = 500µA) and VOL ≤0.3V (ISINK = 1.2mA), ensuring reliable logic-level compatibility across 1.2V–5.5V supply ranges. MR features 10kΩ internal pullup and 250ns MR-to-reset delay, supporting direct connection to momentary switches without external debounce.

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 space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK22D2S+T, MAX6864UK22D2S+T offers identical supervision parameters but inverted reset polarity, while TPS3837K22DBVR omits watchdog functionality and consumes significantly more current - making MAX6865UK22D2S+T the sole choice for long-life, watchdog-protected 2.2V systems.

Availability

MAX6865UK22D2S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and low-power wireless sensors requiring stable component supply and long-term lifecycle support.

Supply support for MAX6865UK22D2S+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 delivers nanopower supervisory functions targeting battery-critical portable medical and IoT devices where ultra-low ICC and guaranteed reset validity at low VCC are mandatory design requirements.

FAQ

What is the exact reset threshold voltage of the MAX6865UK22D2S+T?

The MAX6865UK22D2S+T has a factory-trimmed reset threshold of 2.235V, with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "22" corresponds to 2.235V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for systems with tight supply margins.

Does the MAX6865UK22D2S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK22D2S+T includes a watchdog timer with a typical timeout of 209s, denoted by the "L" suffix in the part number. This long-duration supervision is designed for firmware that performs infrequent tasks - such as hourly sensor reads - and clears the timer on any WDI edge (rising or falling). The timer remains disabled while RESET is asserted.

What type of reset output does the MAX6865UK22D2S+T provide?

The MAX6865UK22D2S+T provides an active-high push-pull RESET output (Pin 1), meaning it 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) and VOL ≤0.3V (at ISINK = 1.2mA) ensure robust interfacing with modern low-voltage µPs.

How is the reset timeout period configured on the MAX6865UK22D2S+T?

The MAX6865UK22D2S+T uses fixed reset timeout configuration: the "D2" suffix specifies a minimum 40ms timeout period (typical 60ms, max 80ms). This value is factory-set and non-adjustable - unlike the CT-pin variants (e.g., MAX6861–MAX6863), the MAX6865UK22D2S+T does not support runtime timeout selection. The timeout begins after VCC exceeds the threshold and MR deasserts.

Is the MAX6865UK22D2S+T compatible with 1.8V microcontrollers?

Yes, the MAX6865UK22D2S+T operates across 1.2V–5.5V and is fully compatible with 1.8V µPs. Its MR input accepts 0.3×VCC VIL and 0.7×VCC VIH, and its active-high RESET output delivers VOH ≥0.8×VCC at ISOURCE = 500µA - meeting standard 1.8V CMOS logic thresholds. The 170nA supply current also minimizes loading on 1.8V LDOs in battery-powered designs.