Analog Devices Inc./Maxim Integrated MAX6865UK35D3L+T

Overview

The MAX6865UK35D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (3.5V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 150ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK35D3L+T datasheet, MAX6865UK35D3L+T pinout, MAX6865UK35D3L+T application, or MAX6865UK35D3L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), 209s watchdog timeout option (L suffix), and compatibility with low-voltage µP systems requiring <200nA quiescent current.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% reset threshold accuracy over -40°C to +85°C, coupled with a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 209s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator, delivering 150ms (D3) minimum delay with ±25% variation over temperature.

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection; RESET output is push-pull active-low with VOL ≤ 0.3V at 1.2mA sink (VCC ≥ 2.38V) and VOH ≥ 0.8×VCC at 500µA source - enabling direct interfacing with 1.8V/2.5V/3.3V µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK35D3L+T, the MAX6865UK35D3L+T offers identical core supervision but adds MR input for field serviceability; versus TPS3838K33DBVR, it delivers 10× lower ICC and integrated watchdog - critical for portable medical and long-life IoT designs.

Availability

MAX6865UK35D3L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered wearables, and industrial handheld terminals requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX6865UK35D3L+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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications, with emphasis on reliability and low-power innovation.

The MAX68xx family targets ultra-low-power microprocessor supervision in space-constrained, battery-operated systems - specifically engineered for medical, portable, and energy-harvesting applications demanding nanoscale quiescent current.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D3L+T?

The MAX6865UK35D3L+T has a factory-trimmed reset threshold of 3.500V with ±2.5% tolerance over -40°C to +85°C, as defined by the "35" suffix in its part number per Maxim's Threshold Suffix Guide (Table 2). This value is laser-trimmed during production and does not require external calibration.

Does the MAX6865UK35D3L+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK35D3L+T includes a watchdog timer with a typical timeout period of 209 seconds, indicated by the "L" suffix in its part number (Table 3). The timer resets on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this interval.

What is the function of Pin 4 (WDI) on the MAX6865UK35D3L+T?

Pin 4 (WDI) on the MAX6865UK35D3L+T is the watchdog input terminal. It monitors µP activity: a rising or falling edge clears the internal watchdog timer, while static high or low states longer than 209s (typ) trigger a reset pulse. The input accepts CMOS logic levels and rejects pulses shorter than 150ns.

Can the MAX6865UK35D3L+T operate reliably at very low supply voltages?

Yes, the MAX6865UK35D3L+T guarantees valid reset assertion down to VCC = +1.1V, as confirmed in the Electrical Characteristics table. Its internal circuitry remains functional and the RESET output maintains specified VOL/VOH performance even during deep brownout conditions.

Is the MAX6865UK35D3L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK35D3L+T uses the standard 5-pin SOT23-5 package and shares identical pinout (RESET, GND, MR, WDI, VCC) with MAX6864/MAX6866 variants. However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6856 (which lack WDI entirely).