Analog Devices Inc./Maxim Integrated MAX6865UK18D6S+T

Overview

The MAX6865UK18D6S+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-high push-pull RESET output when VCC drops below 1.800V (±2.5%), MR is pulled low, or the watchdog expires after 209s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) at 2.5V and guarantees valid reset operation down to VCC = +1.1V.

For engineers reviewing the MAX6865UK18D6S+T datasheet, MAX6865UK18D6S+T pinout, MAX6865UK18D6S+T application, or MAX6865UK18D6S+T equivalent, this device is selected for battery-powered medical monitors, portable instrumentation, and low-voltage embedded controllers requiring guaranteed brownout immunity, glitch-resistant reset timing, and long watchdog timeout with minimal quiescent current.

Technical Context

The MAX6865UK18D6S+T implements a precision bandgap-based voltage monitor with factory-trimmed 1.800V reset threshold (±2.5%) and 0.5% hysteresis, ensuring stable trip points across -40°C to +85°C. Its integrated watchdog timer detects WDI inactivity for ≥209s (typ, L-suffix), clearing on any rising/falling edge and disabling during RESET assertion.

This device uses a dedicated WDI input and MR input with internal 10kΩ pullup, supports no external components, and delivers a push-pull active-high RESET output referenced to VCC with VOH ≥ 0.8×VCC (ISOURCE = 500µA) and 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 supervisors.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK18D6S+T and TPS3838K33DBVR, the MAX6865UK18D6S+T uniquely delivers active-high RESET, precise 1.800V monitoring, 1200ms timeout, and 209s watchdog in one nanopower package - enabling simpler µP interface and longer battery life without design trade-offs.

Availability

MAX6865UK18D6S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial sensor nodes, and smart meter data loggers requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK18D6S+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 battery-critical systems, integrating voltage monitoring, manual reset, and configurable watchdog functionality into miniature SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK18D6S+T?

The MAX6865UK18D6S+T has a factory-trimmed reset threshold of 1.800V with ±2.5% tolerance over -40°C to +85°C, as defined by the "18" suffix in its part number per Maxim's Threshold Suffix Guide. This value is measured at VCC falling and includes 0.5% hysteresis to prevent chatter near the trip point. The MAX6865UK18D6S+T guarantees valid reset assertion down to VCC = +1.1V, making it suitable for deep brownout protection.

Does the MAX6865UK18D6S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK18D6S+T includes a watchdog timer with a nominal timeout of 209 seconds (L-suffix), as indicated by the "S" in its order code. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static (high or low) beyond that period. During RESET assertion, the watchdog is disabled and resumes counting only after RESET deasserts. This behavior is confirmed in the Electrical Characteristics table and Functional Diagram of the MAX6865UK18D6S+T datasheet.

What type of reset output does the MAX6865UK18D6S+T provide?

The MAX6865UK18D6S+T provides an active-high push-pull RESET output on Pin 1, meaning it drives high to release the microprocessor from reset and sinks current to drive low when asserting reset. Unlike open-drain variants, it requires no external pullup resistor. Its VOH is guaranteed ≥0.8×VCC (with 500µA source current) and VOL ≤0.3V (with 1.2mA sink current), ensuring robust interfacing with 1.8V–3.3V µPs. This configuration is explicitly documented in the MAX6865UK18D6S+T Pin Description section.

What is the reset timeout period for the MAX6865UK18D6S+T?

The MAX6865UK18D6S+T has a minimum reset timeout period of 1200ms, denoted by the "D6" suffix in its part number per Table 4 (Reset Timeout Periods). Typical and maximum values are 900ms and 1200ms respectively under standard conditions. This timeout begins after VCC rises above the 1.800V threshold and MR is deasserted, ensuring sufficient time for power supply stabilization and µP internal initialization before release. The MAX6865UK18D6S+T does not support pin-selectable timeout - D6 is fixed for this variant.

How is the manual reset (MR) input configured on the MAX6865UK18D6S+T?

The MR input on the MAX6865UK18D6S+T is an active-low signal with an internal 10kΩ pullup to VCC, allowing it to remain unconnected or tied to VCC when unused. A logic-low pulse ≥1µs on MR forces RESET assertion regardless of VCC or WDI state, and RESET remains asserted for the full 1200ms timeout after MR returns high. MR accepts CMOS-level inputs and is specified for VIH ≥0.7×VCC and VIL ≤0.3×VCC. This behavior is validated in the Electrical Characteristics and Applications Information sections for the MAX6865UK18D6S+T.