Analog Devices Inc./Maxim Integrated MAX6855UK46D4+T

Overview

The MAX6855UK46D4+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 4.625V reset threshold (±2.5%), and 1200ms minimum reset timeout period. It provides active-low push-pull reset output, manual reset input (MR), and operates across -40°C to +85°C - used for reliable power-on reset and brownout protection in battery-powered medical sensors.

For engineers reviewing the MAX6855UK46D4+T datasheet, MAX6855UK46D4+T pinout, MAX6855UK46D4+T application, or MAX6855UK46D4+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), no external components required, and compatibility with CMOS-level MR signaling.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and reset timing control - but excludes watchdog timer functionality (absent in MAX6855 family members). Its internal 10kΩ MR pullup enables direct switch-to-GND interface without external biasing.

The reset output remains asserted for ≥1200ms after VCC rises above 4.625V and MR deasserts, with VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.12V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA - ensuring robust logic-level compatibility with µP reset inputs.

Key Specifications

Pinout & Package

MAX6855UK46D4+T uses a 5-pin SOT23-5 package with exposed pad (not electrically connected). Pin 1 is RESET (active-low push-pull), Pin 2 and Pin 4 are GND, Pin 3 is MR (active-low manual reset input), and Pin 5 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and ADM6805-46ARTZ-R7, the MAX6855UK46D4+T delivers 7× lower supply current and integrated MR functionality - making it uniquely suitable for long-life, user-resettable portable medical devices where 4.625V rail integrity is critical.

Availability

MAX6855UK46D4+T is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered PDAs, wearable health trackers, and industrial handheld terminals requiring stable component supply across extended product lifecycles.

Supply support for MAX6855UK46D4+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 connectivity applications - with emphasis on low-power, high-reliability solutions for demanding environments.

The MAX6855UK46D4+T belongs to the MAX6854–MAX6869 nanopower µP supervisory family, engineered specifically for ultra-low-current battery-powered systems requiring precise voltage monitoring, manual reset, and deterministic reset timing without external components.

FAQ

What is the exact reset threshold voltage of the MAX6855UK46D4+T?

The MAX6855UK46D4+T has a factory-trimmed reset threshold voltage of +4.625V, 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 "46" corresponds to 4.625V nominal. The MAX6855UK46D4+T maintains this specification without requiring external calibration or trimming components.

Does the MAX6855UK46D4+T include a watchdog timer function?

No, the MAX6855UK46D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout functionality. The MAX6855UK46D4+T is a manual-reset-only supervisory circuit with voltage monitoring and fixed reset timeout - confirmed by its absence from the WDI-capable part rows in the ordering table and functional diagram.

What is the reset timeout period for the MAX6855UK46D4+T?

The MAX6855UK46D4+T has a minimum reset timeout period of 1200ms, indicated by the "D4" suffix in its part number. Table 4 (Reset Timeout Periods) specifies D4 as 1200ms (min) / 1800ms (typ) / 2400ms (max). This timeout begins after VCC exceeds the 4.625V threshold and MR is deasserted, ensuring sufficient time for µP initialization before release from reset.

Is the MAX6855UK46D4+T pin-compatible with other SOT23-5 supervisory ICs?

Yes, the MAX6855UK46D4+T uses standard SOT23-5 pinout (Pin 1: RESET, Pins 2&4: GND, Pin 3: MR, Pin 5: VCC) and is explicitly noted as pin-compatible with TPS3836/TPS3837/TPS3838 series in the datasheet Features section. However, electrical differences - such as 170nA vs. ~1.2µA supply current and 4.625V vs. 3.08V threshold - require validation in target circuitry before substitution.

What is the maximum VCC transient duration the MAX6855UK46D4+T can ignore?

The MAX6855UK46D4+T can ignore VCC transients up to 40µs in duration when the overdrive is 100mV (i.e., VCC falls from 4.725V to below 4.625V). This immunity is documented in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph (Figure MAX684 toc05) and ensures robust operation in electrically noisy environments like motor-driven handheld devices - a key reliability feature of the MAX6855UK46D4+T.