Analog Devices Inc./Maxim Integrated MAX6855UK18D2+T

Overview

The MAX6855UK18D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 1.8V reset threshold (±2.5%), and 40ms minimum reset timeout period. It provides active-low push-pull reset output, manual reset input (MR), and operates across -40°C to +85°C for reliable power-up/brownout monitoring in battery-powered systems.

For engineers reviewing the MAX6855UK18D2+T datasheet, MAX6855UK18D2+T pinout, MAX6855UK18D2+T application, or MAX6855UK18D2+T equivalent, this device serves as a precision voltage monitor with deterministic reset timing, low-power operation down to VCC = 1.1V, and immunity to short VCC transients - critical for portable medical and consumer electronics design validation.

Technical Context

This IC integrates three core functions: precise VCC voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with 1µs minimum pulse width and 200ns glitch rejection, and a fixed 40ms reset timeout timer that holds RESET asserted after VCC recovery or MR deassertion. The internal 10kΩ MR pullup eliminates external components.

It operates over 1.2V–5.5V supply range and guarantees valid reset output down to VCC = 1.1V. Its push-pull active-low RESET output drives low to 0.3V at 1.2mA sink current (VCC ≥ 2.38V), enabling direct interface with standard CMOS µP reset inputs without external pullups.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint ideal for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6855UK18D2+T, TPS3836K33DBVR offers no 1.8V option and consumes 7× more current, while MAX6326UR29+T lacks the required 1.8V threshold and 40ms timeout - making MAX6855UK18D2+T uniquely suited for ultra-low-power 1.8V portable designs.

Availability

MAX6855UK18D2+T is available at Aetrix Electronics and suitable for portable medical devices, wearable health monitors, smart consumer electronics, and industrial handheld terminals requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6855UK18D2+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 interface applications, with emphasis on low-power, high-reliability solutions.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality for battery-critical systems, targeting portable medical, wearables, and energy-harvesting applications where µA-level current and sub-2V thresholds are essential.

FAQ

What is the exact reset threshold voltage of the MAX6855UK18D2+T?

The MAX6855UK18D2+T has a factory-trimmed reset threshold of 1.800V with ±2.5% tolerance (1.755V to 1.845V), as defined by the "18" suffix in its part number per Maxim's Threshold Suffix Guide. This value is guaranteed over -40°C to +85°C and applies to VCC falling conditions. The device also provides 0.5% VTH hysteresis to prevent chatter near the threshold.

Does the MAX6855UK18D2+T include a watchdog timer function?

No, the MAX6855UK18D2+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset functionality. Watchdog capability is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UK18D2S+T), identifiable by the "S" or "L" suffix in the ordering code.

What is the function of Pin 4 on the MAX6855UK18D2+T?

Pin 4 on the MAX6855UK18D2+T is a second GND terminal, not a no-connect or I.C. pin. Per the MAX6854/MAX6855/MAX6856 pin configuration diagram, Pins 2 and 4 are both connected to internal ground. This dual-GND layout improves noise immunity and thermal performance in high-density PCB designs without requiring additional routing.

Can the MAX6855UK18D2+T operate reliably at VCC = 1.2V?

Yes, the MAX6855UK18D2+T is fully specified to operate at VCC = 1.2V, the minimum rated supply voltage. At this level, it maintains 170nA typical supply current, asserts valid RESET down to VCC = 1.1V, and meets all electrical characteristics including MR input thresholds and RESET output drive strength - making it suitable for single-cell alkaline or NiMH systems.

Is the MAX6855UK18D2+T pin-compatible with other devices in the MAX685x family?

Yes, the MAX6855UK18D2+T shares identical 5-pin SOT23-5 pinout with all MAX6854/MAX6855/MAX6856 variants, including same RESET (Pin 1), GND (Pins 2 & 4), MR (Pin 3), and VCC (Pin 5) assignments. This allows direct substitution within the same threshold/time-out variant group, provided the reset output polarity (active-low push-pull here) matches the target design.