Analog Devices Inc./Maxim Integrated MAX6855UK29D5+T

Overview

The MAX6855UK29D5+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 2.925V reset threshold with 300ms minimum reset timeout period. It monitors VCC supply integrity, asserts reset during brownout or manual trigger, and guarantees valid reset operation down to VCC = +1.1V. Designed for ultra-low-power portable systems such as glucose monitors and MP3 players.

For engineers reviewing the MAX6855UK29D5+T datasheet, MAX6855UK29D5+T pinout, MAX6855UK29D5+T application, or MAX6855UK29D5+T equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative options - all grounded in Maxim's official specifications for the precise part number.

Technical Context

The MAX6855UK29D5+T implements a voltage-monitoring comparator with ±2.5% threshold accuracy over temperature, a 300ms minimum reset timeout timer, and an internally pulled-up MR input (10kΩ). Its active-high push-pull RESET output drives high when VCC falls below 2.925V or MR is asserted, remaining high for ≥300ms after VCC recovers and MR deasserts.

No watchdog timer or CT select input is present - this variant belongs to the MAX6855 subgroup, confirmed by its ordering code suffix "D5" (300ms timeout) and absence of WDI/CT pins. It shares pinout and functional behavior with MAX6854/MAX6856 but differs in reset polarity and output type.

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 MAX6854UK29D5+T and TPS3837K29, the MAX6855UK29D5+T uniquely provides active-high reset with manual reset support in a drop-in SOT23-5 footprint - enabling direct replacement in designs requiring guaranteed high-level reset assertion and field serviceability.

Availability

MAX6855UK29D5+T is available at Aetrix Electronics and suitable for glucose monitors, portable audio players, patient loggers, and wireless sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6855UK29D5+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 applications.

The MAX685x family was designed specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer electronics, emphasizing nanoscale current draw and guaranteed reset validity at ultra-low VCC.

FAQ

What is the exact reset threshold voltage of the MAX6855UK29D5+T?

The MAX6855UK29D5+T has a factory-trimmed reset threshold of 2.925V, with ±2.5% tolerance over the full -40°C to +85°C temperature range. This value is encoded in the "29" suffix per Maxim's Threshold Suffix Guide (Table 2), and is confirmed in the Electrical Characteristics table under VTH parameter. The MAX6855UK29D5+T maintains this threshold accuracy without external calibration.

Does the MAX6855UK29D5+T include a watchdog timer?

No, the MAX6855UK29D5+T does not include a watchdog timer. It belongs to the MAX6855 subgroup, which features only voltage monitoring and manual reset functionality. Watchdog capability is exclusive to MAX6864–MAX6869 variants (denoted by "S" or "L" suffixes in ordering code). The MAX6855UK29D5+T pinout lacks WDI, confirming absence of watchdog circuitry.

What is the function of Pin 4 on the MAX6855UK29D5+T?

Pin 4 on the MAX6855UK29D5+T is a second GND terminal, electrically connected internally to Pin 2. Its inclusion improves noise immunity and reduces ground bounce in high-speed or high-current switching environments. Per Maxim's Pin Description table and SOT23 top-view diagram, both Pins 2 and 4 serve as ground connections - no signal routing or external connection is required beyond standard grounding practices.

Can the MAX6855UK29D5+T operate from a 1.8V supply?

Yes, the MAX6855UK29D5+T operates from 1.2V to 5.5V, including 1.8V nominal rails. At VCC = 1.8V, its supply current is 170nA (typ), reset threshold remains 2.925V (ensuring detection of brownout relative to higher-voltage domains), and RESET output is guaranteed valid down to VCC = +1.1V. This makes it suitable for mixed-voltage systems where it supervises a higher rail while powered from a lower one.

Is the MAX6855UK29D5+T pin-compatible with the TPS3837K29?

No, the MAX6855UK29D5+T is not pin-compatible with the TPS3837K29. Although both are 5-pin SOT23 supervisory circuits, their pin mappings differ: MAX6855UK29D5+T uses Pins 1=RESET, 2=GND, 3=MR, 4=GND, 5=VCC; TPS3837K29 assigns Pins 1=GND, 2=VCC, 3=MR, 4=RESET, 5=NC. Direct substitution would cause incorrect power and signal connections, risking device damage or malfunction.