Analog Devices Inc./Maxim Integrated MAX6855UK25D5+T

Overview

The MAX6855UK25D5+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 2.5V reset threshold. It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), with a guaranteed minimum 300ms reset timeout period and ultra-low 170nA typical supply current. It is designed for reliable power-on reset and fault recovery in battery-powered medical and portable electronics.

For engineers reviewing the MAX6855UK25D5+T datasheet, MAX6855UK25D5+T pinout, MAX6855UK25D5+T application, or MAX6855UK25D5+T equivalent, key selection criteria include its 2.5V reset threshold accuracy (±2.5%), 300ms minimum reset timeout, operation down to VCC = 1.1V, immunity to short VCC transients, and compatibility with CMOS-level MR inputs requiring no external components.

Technical Context

This device implements a precision voltage monitor with hysteresis (0.5% of VTH) and a digital reset timer that holds the active-high RESET output asserted for ≥300ms after VCC rises above 2.5V and MR deasserts. Its internal 10kΩ MR pullup enables direct connection to momentary switches without external biasing.

The MAX6855UK25D5+T belongs to the MAX6854–MAX6869 family but excludes watchdog timer functionality - confirmed by Selector Guide and Pin Description tables showing no WDI pin and absence of watchdog timing parameters in its electrical characteristics. It supports push-pull active-high reset only, distinguishing it from open-drain or active-low variants.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SC-70/SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K25DBVR and MAX6315US25D3+, the MAX6855UK25D5+T uniquely delivers active-high push-pull reset, sub-µA supply current, and guaranteed operation down to 1.1V - making it optimal for space-constrained, ultra-low-power medical and portable designs where reset polarity and battery longevity are critical.

Availability

MAX6855UK25D5+T is available at Aetrix Electronics and suitable for portable glucose monitors, patient vital sign loggers, and industrial handheld scanners requiring stable component supply with long-lifecycle assurance.

Supply support for MAX6855UK25D5+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 high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications markets.

The MAX6854–MAX6869 family was engineered for ultra-low-power microprocessor supervision in battery-critical applications, emphasizing nanoscale current consumption, wide VCC range, and robust reset timing without external components.

FAQ

What is the exact reset threshold voltage of the MAX6855UK25D5+T?

The MAX6855UK25D5+T has a factory-trimmed reset threshold of 2.500V, with guaranteed tolerance of ±2.5% (2.438V to 2.563V) over the full -40°C to +85°C temperature range. This value is defined in Table 2 (Threshold Suffix Guide) and confirmed in the Electrical Characteristics table under "VCC Reset Threshold (VTH)" with "25" suffix corresponding to 2.5V nominal.

Does the MAX6855UK25D5+T include a watchdog timer function?

No, the MAX6855UK25D5+T does not include a watchdog timer. Per the Selector Guide and Pin Description, MAX6855 is explicitly listed without WDI (Watchdog Input) and belongs to the non-watchdog subgroup (MAX6854/MAX6855/MAX6856). Its functional diagram and timing figures confirm only VCC monitoring and MR-triggered reset - no watchdog circuitry is present in the MAX6855UK25D5+T.

What is the minimum reset timeout period for the MAX6855UK25D5+T?

The MAX6855UK25D5+T has a minimum reset timeout period of 300ms, as indicated by the "D5" suffix in its part number. This is verified in Table 4 (Reset Timeout Periods), where D5 corresponds to 300ms (min), 450ms (typ), and 600ms (max). The timeout begins after VCC exceeds the 2.5V threshold and MR is deasserted.

Can the MAX6855UK25D5+T operate with a supply voltage below 1.8V?

Yes, the MAX6855UK25D5+T operates from 1.2V to 5.5V and guarantees valid reset assertion down to VCC = 1.1V. Its supply current remains ultra-low (170nA typ) even at 1.8V, and the reset output remains functional during brownout - enabling use in single-cell alkaline or NiMH systems where voltage drops below 1.8V during discharge.

What is the function of Pin 4 on the MAX6855UK25D5+T?

Pin 4 on the MAX6855UK25D5+T is a second GND terminal, electrically connected to Pin 2 internally. Its inclusion in the 5-pin SOT23 package improves thermal performance and reduces ground impedance in high-noise environments. Both GND pins must be connected to the same system ground plane per the Typical Operating Circuit and Pin Configurations diagrams.