Analog Devices Inc./Maxim Integrated MAX6865UK35D1S+T

Overview

The MAX6865UK35D1S+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%), 10ms 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 brownout or software lockup.

For engineers reviewing the MAX6865UK35D1S+T datasheet, MAX6865UK35D1S+T pinout, MAX6865UK35D1S+T application, or MAX6865UK35D1S+T equivalent, key selection criteria include 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 CMOS-level MR/WDI inputs.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a monostable reset timeout generator (10ms min), and a watchdog timer that clears on any WDI edge and expires if WDI remains static >3.3s (typ). The internal 10kΩ MR pullup eliminates external components for manual reset implementation.

The MAX6865UK35D1S+T uses BiCMOS process technology (2848 transistors) and operates across -40°C to +85°C. Its push-pull active-high RESET output is referenced to VCC and guarantees VOH ≥ 0.8×VCC at ISOURCE = 500µA when VCC ≥ 2.38V, enabling direct interfacing with µP reset inputs requiring high-active assertion.

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 MAX6865UK35D1S+T, MAX6864UK35D1S+T requires additional passive components and alters reset signaling topology, while TPS3836K33DBVR sacrifices nanopower operation and failsafe software monitoring-making MAX6865UK35D1S+T the optimal choice for battery-critical, safety-aware embedded systems.

Availability

MAX6865UK35D1S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and feature phones requiring stable component supply with long-term lifecycle support and traceable sourcing.

Supply support for MAX6865UK35D1S+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 interface applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family delivers nanopower supervisory solutions optimized for battery-operated portable equipment where ultra-low ICC, guaranteed reset validity at low VCC, and integrated watchdog functionality are critical.

FAQ

What is the exact reset threshold voltage of MAX6865UK35D1S+T?

The MAX6865UK35D1S+T has a factory-trimmed reset threshold of 3.500V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where suffix '35' corresponds to 3.500V nominal, and Electrical Characteristics specify VTH = VTH ±2.5% under all conditions. The MAX6865UK35D1S+T maintains this accuracy without external calibration.

Does MAX6865UK35D1S+T support active-high or active-low reset output?

The MAX6865UK35D1S+T features an active-high push-pull RESET output, as confirmed in the MAX6865 pin description (page 8) and Selector Guide (page 16). Pin 1 drives high during reset assertion and low during deassertion. This differs from MAX6864 (active-low) and MAX6866 (open-drain active-low), making MAX6865UK35D1S+T directly compatible with µPs requiring high-active reset signals.

What is the watchdog timeout period for MAX6865UK35D1S+T?

The MAX6865UK35D1S+T has a watchdog timeout period of 3.3s typical, as indicated by the 'S' suffix in its part number per Table 3 (Watchdog Timeout). Electrical Characteristics confirm tWD = 1.5s (min) / 3.3s (typ) / 7.75s (max) for S-suffix devices. The timer resets on any WDI edge and expires only if WDI remains static beyond this interval.

Can MAX6865UK35D1S+T operate reliably below 1.8V supply voltage?

Yes, the MAX6865UK35D1S+T guarantees reset functionality down to VCC = +1.1V, as specified in Electrical Characteristics (VCC min = 1.2V operating, reset valid to 1.1V). Supply current remains ultra-low (170nA typ at 1.8V), and RESET output maintains VOH ≥ 0.8×VCC at ISOURCE = 500µA when VCC ≥ 2.38V - confirming robust operation across its full 1.2V–5.5V range.

Is MAX6865UK35D1S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK35D1S+T uses the standard 5-pin SOT23-5 package and shares identical pinout with MAX6864/MAX6866 (Pin 1=RESET, 2=GND, 3=MR, 4=WDI, 5=VCC), as shown in Figure 15 (Pin Configurations). However, RESET polarity differs: MAX6865UK35D1S+T is active-high push-pull, while MAX6864 is active-low. Direct replacement requires verification of host µP reset input logic level requirements.