Analog Devices Inc./Maxim Integrated MAX6855UK27D4+T

Overview

The MAX6855UK27D4+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 2.700V reset threshold (suffix "27"), and a 1200ms minimum reset timeout period (suffix "D4"). It provides active-high push-pull RESET output, manual reset input (MR), and operates across –40°C to +85°C for reliable power-up/brownout monitoring in battery-critical systems.

For engineers reviewing the MAX6855UK27D4+T datasheet, MAX6855UK27D4+T pinout, MAX6855UK27D4+T application, or MAX6855UK27D4+T equivalent, this device serves as a precision voltage monitor with deterministic reset timing, manual reset control, and guaranteed reset validity down to VCC = +1.1V - essential for portable medical devices, wearables, and low-power IoT endpoints where supply stability and energy efficiency are non-negotiable.

Technical Context

The MAX6855UK27D4+T implements a precision bandgap-based voltage detector with ±2.5% reset threshold accuracy over temperature, coupled with a monolithic timeout timer that holds RESET asserted for ≥1200ms after VCC rises above 2.700V and MR deasserts. Its active-high push-pull output drives directly to VCC without external pullup, eliminating leakage concerns in always-on systems.

It features internal 10kΩ MR pullup, 250ns MR-to-reset delay, and immunity to VCC transients ≤40µs at 100mV overdrive. Unlike watchdog-equipped variants, the MAX6855UK27D4+T omits WDI and CT pins - confirming its role as a dedicated voltage-monitoring supervisor with fixed timing and no programmable watchdog or timeout selection.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), footprint-compatible with industry-standard 5-lead SOT packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K27DBVR and ADM6805-27ARTZ-RL, the MAX6855UK27D4+T delivers the lowest ICC (170nA) and tightest threshold accuracy (±2.5%) within its temperature range, making it optimal for ultra-long-life portable medical and sensor applications where every nanoamp impacts product lifetime.

Availability

MAX6855UK27D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient wearables, industrial wireless sensors, and smart meter battery backup systems requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX6855UK27D4+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family was engineered specifically for nanopower microprocessor supervision in space- and energy-constrained portable electronics, emphasizing ultra-low ICC, guaranteed low-VCC reset validity, and minimal external component count.

FAQ

What is the exact reset threshold voltage of the MAX6855UK27D4+T?

The MAX6855UK27D4+T has a factory-trimmed reset threshold of 2.700V, with ±2.5% tolerance over the full –40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "27" corresponds to 2.700V nominal. The MAX6855UK27D4+T maintains this accuracy without external calibration or trimming components.

Does the MAX6855UK27D4+T include a watchdog timer function?

No, the MAX6855UK27D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description tables, only MAX6864–MAX6869 variants feature WDI functionality. The MAX6855UK27D4+T is a dedicated voltage supervisor with manual reset (MR) and fixed reset timeout - confirmed by its pinout (no WDI pin) and absence of watchdog-related electrical characteristics in its datasheet section.

What is the reset output configuration of the MAX6855UK27D4+T?

The MAX6855UK27D4+T features an active-high push-pull RESET output, as specified in the MAX6854/MAX6855/MAX6856 Pin Description table. Pin 1 outputs high during reset assertion and low when deasserted - directly compatible with µPs requiring active-high reset inputs or inverters. This eliminates the need for external pullup resistors required by open-drain variants like the MAX6856.

Can the MAX6855UK27D4+T operate reliably below 1.8V supply voltage?

Yes, the MAX6855UK27D4+T operates from 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. Its 170nA supply current and stable 2.700V threshold detection remain functional even at 1.2V input - enabling supervision of ultra-low-voltage microcontrollers and energy-harvesting systems where traditional supervisors fail.

Is the MAX6855UK27D4+T pin-compatible with other devices in the MAX68xx family?

The MAX6855UK27D4+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6869 - but functional compatibility depends on feature set. While physically interchangeable, substitution requires verification of output polarity (active-high vs. active-low), presence of WDI/CT pins, and timeout selection - the MAX6855UK27D4+T is not functionally identical to watchdog or timeout-selectable variants.