Analog Devices Inc./Maxim Integrated MAX6865UK19D3S+T

Overview

The MAX6865UK19D3S+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 1.9V reset threshold (±2.5%), and a 150ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and watchdog timer functionality with 3.3s typical watchdog timeout (S-suffix), and is designed for reliable power-up/power-down sequencing in battery-critical systems.

For engineers reviewing the MAX6865UK19D3S+T datasheet, MAX6865UK19D3S+T pinout, MAX6865UK19D3S+T application, or MAX6865UK19D3S+T equivalent, key selection criteria include its 1.9V VTH tolerance at -40°C to +85°C, guaranteed RESET validity down to VCC = +1.1V, push-pull active-high reset output, and watchdog immunity to short VCC transients - all critical for portable medical and handheld electronics.

Technical Context

This device belongs to the MAX6864–MAX6869 family, which adds watchdog timer functionality to the core supervisory architecture. The MAX6865UK19D3S+T implements a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 3.3s (typ), triggering a full reset timeout cycle.

Its push-pull active-high RESET output is referenced to VCC and guarantees VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA), enabling direct interface with µP reset inputs without external pullups. MR is internally pulled up to VCC via 10kΩ and accepts CMOS-compatible logic levels.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Pin 1 is marked with a dot or bevel; pin numbering follows standard SOT23 top-view convention (counterclockwise from mark).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK19D3S+T and TPS3836K33DBVR, the MAX6865UK19D3S+T uniquely delivers active-high reset, 170nA ICC, and integrated watchdog in one 5-pin SOT23 - making it optimal for space-constrained, battery-sensitive designs requiring both reset polarity compatibility and firmware hang detection.

Availability

MAX6865UK19D3S+T is available at Aetrix Electronics and suitable for portable medical devices, handheld consumer electronics, and battery-powered IoT edge nodes requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK19D3S+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 precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6864–MAX6869 product line was engineered specifically for ultra-low-power microprocessor supervision in battery-operated portable equipment, combining voltage monitoring, manual reset, and watchdog functionality in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6865UK19D3S+T?

The MAX6865UK19D3S+T has a factory-trimmed reset threshold voltage of 1.9V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "19" corresponds to 1.9V nominal VTH. The device guarantees valid reset assertion down to VCC = +1.1V, ensuring reliability even during deep brownout conditions.

Does the MAX6865UK19D3S+T support active-high or active-low reset output?

The MAX6865UK19D3S+T features a push-pull active-high RESET output, as indicated by its "65" part number in the Selector Guide and confirmed in the MAX6865 pin description. When asserted, RESET drives high; when deasserted, it drives low. This eliminates the need for an external pullup resistor and provides direct compatibility with µPs requiring active-high reset signals.

What is the watchdog timeout period for the MAX6865UK19D3S+T?

The MAX6865UK19D3S+T has a watchdog timeout period of 3.3s (typical), denoted by the "S" suffix in its order code. Per Table 3 (Watchdog Timeout), the S-suffix specifies min/typ/max values of 1.5s/3.3s/7.75s. The watchdog timer clears on any rising or falling edge at WDI and expires only if WDI remains static beyond this period, triggering a full reset timeout cycle.

Can the MAX6865UK19D3S+T operate with supply voltages below 1.8V?

Yes, the MAX6865UK19D3S+T operates with VCC from 1.2V to 5.5V and guarantees RESET validity down to VCC = +1.1V. Electrical Characteristics confirm ICC = 170nA (typ) at VCC = 1.8V and functional operation at VCC = 1.2V. Its 1.9V reset threshold remains accurate across this range, making it suitable for single-cell alkaline or LiFePO₄ systems nearing end-of-discharge.

Is the manual reset input (MR) of the MAX6865UK19D3S+T internally pulled up?

Yes, the MR pin of the MAX6865UK19D3S+T is internally pulled up to VCC through a 10kΩ resistor, as specified in the Pin Description section. This allows direct connection of a momentary switch from MR to GND for manual reset initiation without external components. If unused, MR may be left floating or tied to VCC - no external pullup is required.