Analog Devices Inc./Maxim Integrated MAX6855UK45D4+T

Overview

The MAX6855UK45D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring active-high push-pull reset output, manual reset input (MR), and a factory-trimmed 4.500V reset threshold with 1200ms minimum reset timeout. It monitors VCC for brownout detection, asserts reset during power-up/down, and guarantees valid reset operation down to VCC = +1.1V. It is used in battery-powered glucose monitors and portable medical devices requiring ultra-low quiescent current.

For engineers reviewing the MAX6855UK45D4+T datasheet, MAX6855UK45D4+T pinout, MAX6855UK45D4+T application, or MAX6855UK45D4+T equivalent, key selection criteria include its 4.500V ±2.5% reset threshold, 1200ms reset timeout, 170nA typical supply current at 2.5V, and compatibility with 1.2V–5.5V supply rails in space-constrained, low-power embedded systems.

Technical Context

This device implements a precision voltage monitor with hysteresis (0.5% of VTH), a fixed 1200ms internal reset timeout timer, and an active-low manual reset input with 250ns MR-to-reset delay and 1µs minimum pulse width. Its reset assertion logic is triggered solely by VCC falling below 4.500V or MR being pulled low - no watchdog or CT functionality is present.

The MAX6855UK45D4+T uses a BiCMOS process and delivers guaranteed reset validity down to VCC = +1.1V, with output drive capability of VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA). It requires no external components and is immune to VCC transients ≤40µs at 100mV overdrive.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6855UK45D4+T, the MAX6854UK45D4+T offers identical threshold and timeout but inverted reset polarity and open-drain drive, while the TPS3837K33DBVR trades nanopower operation for broader temperature range and TI's long-term supply assurance - making it suitable for non-battery-critical applications.

Availability

MAX6855UK45D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, and handheld diagnostic tools requiring stable component supply across extended production lifecycles.

Supply support for MAX6855UK45D4+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 in demanding industrial, medical, and automotive applications.

The MAX685x family delivers nanopower supervisory functions for battery-operated medical and portable electronics, emphasizing ultra-low ICC, guaranteed reset validity at low VCC, and robust transient immunity in compact SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6855UK45D4+T?

The MAX6855UK45D4+T has a factory-trimmed reset threshold of +4.500V with ±2.5% tolerance over -40°C to +85°C. This value is defined in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "45" corresponds to 4.500V nominal. The MAX6855UK45D4+T maintains this accuracy across temperature and supply voltage variations without external calibration.

Does the MAX6855UK45D4+T include a watchdog timer function?

No, the MAX6855UK45D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout functionality. The MAX6855UK45D4+T provides voltage monitoring and manual reset only - confirming its role as a dedicated reset supervisor without timing supervision.

What is the reset output configuration of the MAX6855UK45D4+T?

The MAX6855UK45D4+T features an active-high push-pull reset output (labeled RESET on Pin 1), as confirmed in the MAX6854/MAX6855/MAX6856 Pin Description table. Unlike open-drain or active-low variants, this output drives high during reset and low when deasserted, eliminating the need for an external pullup resistor and enabling direct connection to µP reset inputs expecting active-high logic.

Can the MAX6855UK45D4+T operate from a 1.8V supply?

Yes, the MAX6855UK45D4+T operates from 1.2V to 5.5V, including 1.8V. Electrical Characteristics confirm ICC = 170nA typical at VCC = 1.8V, and reset output specifications (VOH ≥ 0.8×VCC, VOL ≤ 0.3V) are guaranteed across this range. Its ability to assert valid reset down to VCC = +1.1V makes it suitable for ultra-low-voltage battery systems.

Is the MAX6855UK45D4+T pin-compatible with other MAX685x devices?

The MAX6855UK45D4+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854 and MAX6856, but differs in reset polarity and drive type. While mechanical footprint is identical, electrical compatibility requires verifying reset logic polarity and drive strength - the MAX6855UK45D4+T's active-high push-pull output is not functionally interchangeable with MAX6854's open-drain or MAX6856's active-low variants without board-level changes.