Analog Devices Inc./Maxim Integrated MAX6855UK28D4+T

Overview

The MAX6855UK28D4+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 fixed 1200ms minimum reset timeout period. It monitors VCC with a factory-trimmed 2.800V reset threshold (±2.5%), asserts reset down to VCC = +1.1V, and draws only 170nA typical supply current - ideal for battery-powered glucose monitors and portable medical devices requiring ultra-low quiescent power and reliable brownout protection.

For engineers reviewing the MAX6855UK28D4+T datasheet, MAX6855UK28D4+T pinout, MAX6855UK28D4+T application, or MAX6855UK28D4+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options - all aligned to the official MAX6854–MAX6869 family specification and ordering documentation.

Technical Context

The MAX6855UK28D4+T implements a voltage-monitoring supervisor with deterministic reset assertion on VCC drop below 2.800V, MR low pulse initiation, and guaranteed reset deassertion after ≥1200ms following VCC recovery and MR release. Its internal 10kΩ MR pullup enables direct switch-to-GND interface without external components.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6855UK28D4+T omits WDI functionality and CT select input - it is a dedicated manual-reset-only device with fixed timeout and active-high push-pull RESET output referenced to VCC.

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 TPS3837K28 and MAX6315US28D4+, the MAX6855UK28D4+T uniquely delivers 170nA supply current - a 15× reduction versus TPS3837K28 and 9× versus MAX6315US28D4+ - enabling multi-year battery life where µA-level leakage would otherwise dominate runtime.

Availability

MAX6855UK28D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and portable audio equipment requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6855UK28D4+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 management, sensing, and interface applications in industrial, medical, and communications systems.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer electronics - emphasizing nanopower operation, factory-trimmed accuracy, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of the MAX6855UK28D4+T?

The MAX6855UK28D4+T has a factory-trimmed reset threshold voltage of 2.800V, with a tolerance of ±2.5% across the –40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "28" corresponds to 2.800V nominal. The MAX6855UK28D4+T does not support adjustable thresholds or external hysteresis tuning.

Does the MAX6855UK28D4+T include a watchdog timer function?

No, the MAX6855UK28D4+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset (MR) functionality. Watchdog capability is exclusive to MAX6864–MAX6869 variants, identifiable by "S" or "L" suffixes in the ordering code - absent in MAX6855UK28D4+T.

What is the function of Pin 4 on the MAX6855UK28D4+T?

Pin 4 on the MAX6855UK28D4+T is a second GND terminal, electrically connected internally to Pin 2. Its inclusion in the 5-pin SOT23 package improves thermal dissipation and reduces ground impedance - critical for maintaining reset threshold accuracy under varying PCB layout and thermal conditions. It must be connected to the same ground net as Pin 2.

Can the MAX6855UK28D4+T drive a reset input that expects active-low signaling?

No - the MAX6855UK28D4+T features an active-high push-pull RESET output (Pin 1), meaning it drives high during reset assertion. To interface with an active-low µP reset input, an external inverter or level-shifting circuit is required. For native active-low compatibility, consider the MAX6854UK28D4+T (push-pull active-low) or MAX6856UK28D4+T (open-drain active-low).

What is the minimum MR pulse width required to trigger reset on the MAX6855UK28D4+T?

The MAX6855UK28D4+T requires a minimum MR pulse width of 1µs to reliably initiate a reset cycle. This specification is explicitly stated in the Electrical Characteristics table under "MR Minimum Pulse Width (tMPW)". The internal MR circuit includes 200ns glitch rejection, ensuring noise immunity while maintaining responsiveness to legitimate manual reset commands.