Analog Devices Inc./Maxim Integrated MAX6865UK37D1S+T

Overview

The MAX6865UK37D1S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 3.7V reset threshold (±2.5%), and a 10ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and watchdog timer functionality with WDI input and active-high push-pull RESET output - designed for reliable power-up/brownout protection in battery-critical portable medical and handheld electronics.

For engineers reviewing the MAX6865UK37D1S+T datasheet, MAX6865UK37D1S+T pinout, MAX6865UK37D1S+T application, or MAX6865UK37D1S+T equivalent, this page delivers verified electrical parameters, functional pin definitions, real-world use cases in glucose monitors and patient monitors, and two validated alternative parts with documented technical and application differences.

Technical Context

The MAX6865UK37D1S+T implements a precision bandgap-based voltage monitor with guaranteed reset validity down to VCC = +1.1V and immunity to short VCC transients (e.g., ≤40µs at 100mV overdrive). Its watchdog timer responds to rising/falling edges on WDI and expires after 3.3s (typ), clearing only upon reset assertion, MR activation, or WDI transition.

This device uses BiCMOS process technology (2848 transistors) and features an internal 10kΩ MR pullup, glitch rejection of 200ns on MR, and MR-to-reset delay of 250ns. The active-high push-pull RESET output sources ≥0.8×VCC at 500µA when deasserted and sinks ≤0.3V at 1.2mA when asserted (VCC ≥ 2.38V).

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, -40°C to +85°C operating range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D1S+T and TPS3837K33DBVR, the MAX6865UK37D1S+T uniquely combines ultra-low 170nA ICC, 3.7V precision threshold, 10ms fast reset timeout, and active-high push-pull RESET - making it optimal for space-constrained, battery-sensitive medical devices requiring both voltage and firmware supervision.

Availability

MAX6865UK37D1S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and portable PDAs requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6865UK37D1S+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, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervisory circuits optimized for battery-powered portable equipment - emphasizing ultra-low ICC, wide VCC range, and integrated watchdog functionality for safety-critical firmware monitoring.

FAQ

What is the exact reset threshold voltage of MAX6865UK37D1S+T?

The MAX6865UK37D1S+T has a factory-trimmed reset threshold of 3.700V with ±2.5% tolerance (3.608V to 3.793V), corresponding to the "37" suffix per Maxim's Threshold Suffix Guide. This value is guaranteed over -40°C to +85°C and ensures reliable detection of brownout on 3.3V systems with adequate margin.

Does MAX6865UK37D1S+T require external components for basic operation?

No, the MAX6865UK37D1S+T operates autonomously with no external components: it includes an internal 10kΩ pullup on MR, precision voltage reference, and timing elements for both reset timeout and watchdog functions. Only a 0.1µF VCC bypass capacitor is recommended for noise immunity - no resistors or timing capacitors are needed.

What is the function of the WDI pin on MAX6865UK37D1S+T?

The WDI (Watchdog Input) pin on MAX6865UK37D1S+T monitors µP firmware activity: if WDI remains static (high or low) for longer than 3.3s (typ), the internal watchdog timer expires and asserts RESET for 10ms. Each rising or falling edge on WDI clears the timer - enabling robust detection of software hangs without requiring precise pulse timing.

How does the active-high push-pull RESET output of MAX6865UK37D1S+T differ from open-drain alternatives?

The MAX6865UK37D1S+T's active-high push-pull RESET eliminates the need for an external pullup resistor, reduces board space, and ensures faster rise/fall times versus open-drain outputs. It sources ≥0.8×VCC at 500µA when deasserted and sinks ≤0.3V at 1.2mA when asserted - providing strong drive strength directly compatible with standard µP reset inputs.

Is MAX6865UK37D1S+T pin-compatible with other devices in the MAX68xx family?

Yes, MAX6865UK37D1S+T shares the same 5-pin SOT23-5 footprint and pinout (RESET, GND, MR, WDI, VCC) with MAX6864/MAX6866/MAX6867–MAX6869 variants. However, pin compatibility does not imply functional equivalence - e.g., MAX6864 offers open-drain RESET, while MAX6865 provides active-high push-pull, requiring schematic review before substitution.