Analog Devices Inc./Maxim Integrated MAX6865UK35D3S+T

Overview

MAX6865UK35D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.5V reset threshold (±2.5%), 150ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP initialization during power-up, brownout, or software hang.

For engineers reviewing the MAX6865UK35D3S+T datasheet, MAX6865UK35D3S+T pinout, MAX6865UK35D3S+T application, or MAX6865UK35D3S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-power systems requiring minimal quiescent current.

Technical Context

The MAX6865UK35D3S+T integrates voltage monitoring, manual reset assertion, and watchdog timer functionality in a single BiCMOS IC. Its reset logic asserts RESET when VCC falls below 3.5V, MR is pulled low, or WDI remains static beyond 3.3s - with internal timing ensuring minimum 150ms reset pulse width after recovery.

It uses an internal 10kΩ pullup on MR and accepts CMOS-level inputs on MR and WDI (VIH = 0.7×VCC, VIL = 0.3×VCC). The push-pull active-high RESET output drives high with VOH ≥ 0.8×VCC (ISOURCE = 500µA) and sinks low with VOL ≤ 0.3V (ISINK = 1.2mA), supporting direct interface to µP reset inputs without external components.

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 MAX6865UK35D3S+T, TPS3837K33DBVR omits watchdog capability and requires external biasing, while MAX6369KA29+T trades lower quiescent current for longer watchdog latency and higher ICC - making MAX6865UK35D3S+T optimal for balanced low-power supervision with responsive fault detection.

Availability

MAX6865UK35D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, smart wearables, and industrial handheld terminals requiring stable component supply across long production lifecycles.

Supply support for MAX6865UK35D3S+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 connectivity applications in industrial, medical, and consumer markets.

The MAX6854–MAX6869 family delivers nanopower supervision for battery-critical systems, with the MAX6865UK35D3S+T specifically engineered for medical-grade reliability and ultra-low ICC in portable diagnostics and monitoring equipment.

FAQ

What is the exact reset threshold voltage of MAX6865UK35D3S+T?

The MAX6865UK35D3S+T has a factory-trimmed reset threshold of 3.500V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix "35" corresponds to VTH = 3.5V, and electrical characteristics specify VTH min/typ/max as 3.413V/3.500V/3.588V. The MAX6865UK35D3S+T maintains this accuracy without external calibration.

Does MAX6865UK35D3S+T support active-high or active-low reset output?

The MAX6865UK35D3S+T features an active-high push-pull RESET output (pin 1), as confirmed in the MAX6864/MAX6865/MAX6866 Pin Description section and Selector Guide. When asserted, RESET drives high to VCC; when deasserted, it drives low to GND. This eliminates need for external pullup resistors and ensures clean logic-level compatibility with µP reset inputs expecting active-high assertion.

What is the watchdog timeout behavior of MAX6865UK35D3S+T?

The MAX6865UK35D3S+T implements a watchdog timer with 3.3s typical timeout (suffix "S"), clearing on any rising or falling edge at WDI (pin 4) and asserting RESET if WDI remains static beyond that period. Electrical Characteristics confirm tWD min/typ/max = 1.5s/3.3s/7.75s. The MAX6865UK35D3S+T watchdog resumes counting immediately after RESET deassertion, enabling tight firmware supervision without gaps.

Can MAX6865UK35D3S+T operate reliably below 1.8V supply?

Yes - the MAX6865UK35D3S+T operates across VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V, as specified in Absolute Maximum Ratings and Electrical Characteristics. At 1.2V, supply current remains ultra-low (190nA typ), and reset threshold retains ±2.5% accuracy. This makes MAX6865UK35D3S+T suitable for end-of-battery-life operation in coin-cell-powered devices.

How does the manual reset (MR) input function on MAX6865UK35D3S+T?

The MR input (pin 3) is active-low with internal 10kΩ pullup to VCC. Driving MR low for ≥1µs initiates reset, holding RESET high for the full 150ms timeout even after MR returns high. MR accepts standard CMOS logic levels (VIH ≥ 0.7×VCC, VIL ≤ 0.3×VCC) and rejects <200ns glitches. No external components are needed - the MAX6865UK35D3S+T handles debounce internally.