Analog Devices Inc./Maxim Integrated MAX6865UK16D3S+T

Overview

MAX6865UK16D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (1.575V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. Used in battery-powered glucose monitors and portable medical devices requiring ultra-low quiescent current.

For engineers reviewing the MAX6865UK16D3S+T datasheet, MAX6865UK16D3S+T pinout, MAX6865UK16D3S+T application, or MAX6865UK16D3S+T equivalent, key selection criteria include its 170nA typical supply current, factory-trimmed 1.575V reset threshold, 150ms minimum reset timeout (D3), 209s watchdog period (S suffix), and active-high push-pull RESET output - all validated for -40°C to +85°C operation.

Technical Context

The MAX6865UK16D3S+T implements a dual-trigger reset architecture: one path responds to VCC falling below 1.575V (±2.5%), another to MR low assertion, and a third to WDI inactivity exceeding 209s (typ). Its internal watchdog timer clears on any WDI edge, MR assertion, or RESET assertion - ensuring robust recovery from software hangs without false triggers.

Reset deassertion follows a fixed 150ms (min) timeout after VCC rises above threshold and MR deasserts; the active-high push-pull output drives directly to VCC with VOH ≥ 0.8×VCC at 500µA source, eliminating external pullups. Immunity to sub-40µs VCC transients (at 100mV overdrive) supports noisy power environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK16D3S+T, MAX6864UK16D3S+T offers identical supervision accuracy and ultra-low power but requires active-low reset compatibility, while TPS3836K33DBVR trades off watchdog capability and nanopower operation for lower unit cost in simpler power-monitoring roles.

Availability

MAX6865UK16D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and handheld medical diagnostics requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK16D3S+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 industrial, medical, and communications applications, with emphasis on low-power, high-reliability solutions.

The MAX6854–MAX6869 family delivers nanopower supervisory functions for battery-critical systems, targeting portable medical equipment and wearables where multi-year operation and fault resilience are mandatory.

FAQ

What is the reset threshold voltage of MAX6865UK16D3S+T?

The MAX6865UK16D3S+T has a factory-trimmed reset threshold of +1.575V, with ±2.5% tolerance over -40°C to +85°C. This value is encoded in the "16" suffix per Maxim's Threshold Suffix Guide and is validated for reliable brownout detection on 1.8V or 1.5V supply rails. The MAX6865UK16D3S+T guarantees reset assertion when VCC falls below this threshold and remains asserted for 150ms after VCC exceeds it.

Does MAX6865UK16D3S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK16D3S+T includes a watchdog timer with a typical timeout period of 209 seconds, indicated by the "S" suffix in the part number. The timer resets on any rising or falling edge at the WDI pin and triggers a reset if no edge occurs within the timeout window. This long interval supports firmware with infrequent background tasks while maintaining fault coverage. The MAX6865UK16D3S+T watchdog is disabled only when RESET is asserted.

What type of RESET output does MAX6865UK16D3S+T provide, and how is it configured?

The MAX6865UK16D3S+T provides an active-high push-pull RESET output, meaning it drives high during reset assertion and low when deasserted. This configuration eliminates the need for an external pullup resistor and directly interfaces with µPs requiring active-high reset signals. Pin 1 is dedicated to this function, and the output is referenced to VCC with VOH ≥ 0.8×VCC at 500µA source current. The MAX6865UK16D3S+T does not support open-drain or active-low variants.

What is the supply current of MAX6865UK16D3S+T, and how does it vary with operating conditions?

The MAX6865UK16D3S+T draws 170nA typical supply current at +25°C and VCC = 2.5V, with maximum 400nA across -40°C to +85°C. Current increases slightly with VCC (e.g., 190nA at 3.3V, 210nA at 5.0V) but remains stable under watchdog toggling up to 1MHz. This nanopower consumption enables multi-year operation on coin cells. The MAX6865UK16D3S+T maintains this ultra-low ICC regardless of MR or WDI activity, making it ideal for always-on medical sensors.

How is the reset timeout period determined for MAX6865UK16D3S+T?

The reset timeout period for MAX6865UK16D3S+T is fixed at 150ms minimum (225ms typical, 300ms maximum), encoded by the "D3" suffix per Maxim's Reset Timeout Period Table. This duration begins when VCC rises above 1.575V and MR is deasserted, and ends when RESET deasserts. The timeout is internally generated and unaffected by external components. Unlike MAX6861–MAX6863, the MAX6865UK16D3S+T does not support pin-selectable timeout options.