Analog Devices Inc./Maxim Integrated MAX6855UK35D4+T

Overview

MAX6855UK35D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring active-high push-pull reset output, 3.5V factory-trimmed reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and immunity to VCC transients down to 1.1V. It monitors supply voltage during power-up/down/brownout in ultra-low-power portable medical and consumer devices.

For engineers reviewing the MAX6855UK35D4+T datasheet, MAX6855UK35D4+T pinout, MAX6855UK35D4+T application, or MAX6855UK35D4+T equivalent, this page delivers verified electrical specs, functional pin roles, real-world use cases, and validated alternative parts for battery-powered system design and reliability-critical reset management.

Technical Context

The MAX6855UK35D4+T implements a precision bandgap-based voltage monitor with hysteresis (0.5% of VTH) and a digital timeout counter. Its MR input is internally pulled up to VCC via 10kΩ and accepts CMOS logic levels, with 1µs minimum pulse width and 200ns glitch rejection.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6855UK35D4+T lacks WDI and CT pins - it is a fixed-threshold, fixed-timeout, MR-enabled supervisory IC with no programmable timing or watchdog functionality. Reset assertion is triggered solely by VCC falling below 3.5V or MR low assertion.

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 TPS3837K33DBVR and ADM6806-3ARTZ-RL7, the MAX6855UK35D4+T uniquely combines 3.5V threshold, 1200ms timeout, active-high push-pull output, and MR support in a single nanopower device - making it optimal for next-gen portable medical and consumer electronics requiring long battery life and user-recoverable reset capability.

Availability

MAX6855UK35D4+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and smart pagers requiring stable component supply across extended production lifecycles and global regulatory compliance.

Supply support for MAX6855UK35D4+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 in industrial, medical, and consumer markets.

The MAX685x family targets ultra-low-power microprocessor supervision in battery-constrained systems, emphasizing nanoscale ICC, guaranteed reset validity at low VCC, and robust transient immunity - specifically for portable medical and handheld electronics.

FAQ

What is the exact reset threshold voltage of the MAX6855UK35D4+T?

The MAX6855UK35D4+T has a factory-trimmed reset threshold of 3.500V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "35" corresponds to 3.500V nominal. The MAX6855UK35D4+T maintains this accuracy without external calibration or trimming components.

Does the MAX6855UK35D4+T include a watchdog timer function?

No, the MAX6855UK35D4+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., MAX6864UK16D3S), identifiable by the "S" or "L" suffix in the part number. The MAX6855UK35D4+T pinout lacks WDI and related internal circuitry.

What is the function of Pin 4 on the MAX6855UK35D4+T?

Pin 4 on the MAX6855UK35D4+T is a second GND terminal, electrically connected to Pin 2 internally. Its inclusion improves noise immunity and reduces ground bounce in high-speed or RF-sensitive layouts. Unlike variants such as MAX6858/MAX6860, the MAX6855UK35D4+T does not repurpose Pin 4 as I.C. or CT - it serves solely as an auxiliary ground path per the SOT23 pin configuration diagram.

Can the MAX6855UK35D4+T operate with a 1.8V supply?

Yes, the MAX6855UK35D4+T operates with VCC as low as 1.2V and guarantees valid reset assertion down to VCC = 1.1V. At 1.8V, its supply current is 170nA (typ), reset threshold remains 3.5V ±2.5%, and output drive strength meets spec (VOH ≥ 0.8×VCC at ISOURCE = 200µA). However, since 1.8V < 3.5V, the device will assert reset continuously - it is intended for monitoring rails ≥3.5V, not powering from them.

Is the MAX6855UK35D4+T pin-compatible with other MAX685x devices?

The MAX6855UK35D4+T shares the same 5-pin SOT23-5 footprint and pinout (RESET, GND, MR, GND, VCC) with MAX6854 and MAX6856, but differs functionally: MAX6854 uses active-low push-pull RESET, MAX6856 uses open-drain RESET, while MAX6855UK35D4+T uses active-high push-pull. Swapping requires verifying µP reset polarity and removing any external pullup resistor used for open-drain variants.