Analog Devices Inc./Maxim Integrated MAX6855UK44D2+T

Overview

The MAX6855UK44D2+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 factory-trimmed 4.266V (min) / 4.375V (typ) / 4.484V (max) reset threshold voltage. It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), with guaranteed reset validity down to VCC = +1.1V and ultra-low 170nA typical supply current. It is used in battery-powered medical monitors and portable electronics requiring reliable power-on reset and low-quiescent-current supervision.

For engineers reviewing the MAX6855UK44D2+T datasheet, MAX6855UK44D2+T pinout, MAX6855UK44D2+T application, or MAX6855UK44D2+T equivalent, this page delivers verified functional identity, confirmed pin mapping, exact reset threshold and timeout values, real-world timing behavior under temperature variation, and validated alternative parts for design continuity.

Technical Context

The MAX6855UK44D2+T implements a precision voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, internal 10kΩ MR pullup, and fixed 40ms minimum reset timeout (D2 option). Its active-high push-pull RESET output is referenced to VCC and sinks ≤0.3V at 1.2mA load when asserted, while sourcing ≥0.8×VCC when deasserted - enabling direct interface with µP reset inputs without external components.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6855UK44D2+T lacks WDI functionality and CT input; it belongs to the MR-only, fixed-threshold/fixed-timeout subgroup of the MAX6854–MAX6869 family. Its reset assertion is triggered solely by VCC falling below 4.375V (typ) or MR low, with immunity to VCC transients ≤40µs at 100mV overdrive.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6326UR29+T, the MAX6855UK44D2+T offers the highest threshold accuracy (±2.5%), lowest supply current (170nA), and optimal 40ms timeout for modern low-power MCUs - making it superior for long-life, high-reliability medical and portable designs.

Availability

MAX6855UK44D2+T is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered PDAs, and low-power IoT sensor nodes requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6855UK44D2+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 consumer systems.

The MAX6854–MAX6869 product line delivers nanopower supervisory circuits optimized for battery-critical applications where sub-µA quiescent current, factory-trimmed thresholds, and robust reset timing are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6855UK44D2+T?

The MAX6855UK44D2+T has a factory-trimmed reset threshold of 4.266V (minimum), 4.375V (typical), and 4.484V (maximum) over the full -40°C to +85°C temperature range. This value is encoded in the "44" suffix per Maxim's Threshold Suffix Guide and is guaranteed without external calibration. The MAX6855UK44D2+T uses this precise threshold to ensure reliable reset assertion before microprocessor undervoltage lockout occurs.

Does the MAX6855UK44D2+T include a watchdog timer function?

No, the MAX6855UK44D2+T does not include a watchdog timer. It belongs to the MR-only subgroup (MAX6854/MAX6855/MAX6856) within the MAX6854–MAX6869 family and lacks the WDI input pin and associated watchdog circuitry. Watchdog functionality is exclusive to MAX6864–MAX6869 variants. The MAX6855UK44D2+T relies solely on VCC monitoring and manual reset (MR) for supervision.

What is the reset timeout period for the MAX6855UK44D2+T?

The MAX6855UK44D2+T features a fixed 40ms minimum (60ms typical, 80ms maximum) reset timeout period, indicated by the "D2" suffix in its part number. This timeout begins after VCC rises above the reset threshold and MR is deasserted, ensuring sufficient hold time for microprocessor initialization. The MAX6855UK44D2+T does not support pin-selectable timeout options like the MAX6861–MAX6863 series.

What type of reset output does the MAX6855UK44D2+T provide?

The MAX6855UK44D2+T provides an active-high push-pull reset output on Pin 1. When reset is asserted, RESET drives high to VCC; when deasserted, it drives low to near 0V. This eliminates the need for an external pullup resistor and ensures strong drive capability (≤0.3V low-level at 1.2mA sink). The MAX6855UK44D2+T differs from MAX6854 (open-drain) and MAX6856 (push-pull active-low) in output polarity and structure.

Is the MAX6855UK44D2+T compatible with 1.8V microcontrollers?

Yes, the MAX6855UK44D2+T operates from VCC = 1.2V to 5.5V and guarantees valid reset output down to VCC = +1.1V. Its active-high push-pull output sources ≥0.8×VCC when deasserted and sinks ≤0.3V when asserted - fully compatible with 1.8V logic inputs. However, its 4.375V reset threshold means it is intended for supervision of higher-voltage rails (e.g., 4.5V LDO outputs), not direct 1.8V core supply monitoring.