Analog Devices Inc./Maxim Integrated MAX6865UK37D6S+T

Overview

The MAX6865UK37D6S+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 functionality. It asserts an active-high push-pull RESET output when VCC drops below 3.608V (typ), MR is asserted, or the watchdog expires after 209s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) supply current and guarantees valid reset down to VCC = +1.1V.

For engineers reviewing the MAX6865UK37D6S+T datasheet, MAX6865UK37D6S+T pinout, MAX6865UK37D6S+T application, or MAX6865UK37D6S+T equivalent, key selection criteria include its factory-trimmed 3.608V reset threshold, 1200ms minimum reset timeout (D6), S-suffix 3.3s watchdog option, active-high push-pull RESET output, and compatibility with battery-powered medical and portable electronics requiring robust brownout and code-execution error protection.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over temperature, 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 uses a temperature-stable RC oscillator, delivering guaranteed minimum delay of 600ms (D6 option).

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection; RESET output is push-pull active-high, referenced to VCC, with VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA - enabling direct interfacing with 1.71V–5.5V µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Pin 1 is RESET (active-high push-pull), Pin 2 is GND, Pin 3 is MR (active-low manual reset), Pin 4 is WDI (watchdog input), Pin 5 is VCC (supply voltage input).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D6S+T, the MAX6865UK37D6S+T eliminates external pullup needs and simplifies µP interface; versus TPS3836K33DBVR, it delivers 26× lower supply current and adds critical watchdog protection - making it essential for long-life, safety-relevant portable electronics.

Availability

MAX6865UK37D6S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and low-power wearables requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK37D6S+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 applications.

The MAX6865UK37D6S+T belongs to the MAX6854–MAX6869 nanopower supervisory family, designed specifically for ultra-low-power microprocessor systems where battery longevity, brownout resilience, and runtime code integrity are mission-critical.

FAQ

What is the exact reset threshold voltage of the MAX6865UK37D6S+T?

The MAX6865UK37D6S+T has a factory-trimmed reset threshold voltage of 3.608V (typical), with ±2.5% tolerance over temperature (-40°C to +85°C). This value corresponds to the "37" suffix in the part number per Maxim's Threshold Suffix Guide, and is guaranteed by design across the full operating range.

Does the MAX6865UK37D6S+T require external components for basic operation?

No, the MAX6865UK37D6S+T operates autonomously with no external components required. Its internal 10kΩ MR pullup, precision voltage reference, and RC-based timing circuits eliminate the need for resistors, capacitors, or trimming networks - though a 0.1µF VCC bypass capacitor is recommended for noise immunity.

How does the watchdog timer in the MAX6865UK37D6S+T respond to firmware activity?

The MAX6865UK37D6S+T watchdog timer clears on any rising or falling edge at the WDI pin. If WDI remains static (high or low) for longer than 3.3s (typ), the timer expires and asserts RESET for the full 600–1200ms timeout period. This behavior prevents false timeouts during stable code execution while detecting true hangs.

What is the minimum VCC voltage at which the MAX6865UK37D6S+T guarantees valid RESET output?

The MAX6865UK37D6S+T guarantees valid RESET output down to VCC = +1.1V. Below this voltage, RESET may become indeterminate; however, most µPs cease operation above 1.1V, making this specification sufficient for safe brownout handling in real-world 3.3V and 3.6V systems.

Is the MAX6865UK37D6S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK37D6S+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, WDI, VCC) with MAX6864/MAX6866 variants, but differs from MAX6861–MAX6863 (which use CT instead of WDI) and MAX6854–MAX6856 (which lack WDI). Direct substitution is only valid within the MAX6864–MAX6866 subgroup.