Analog Devices Inc./Maxim Integrated MAX6855UK43D2+T

Overview

The MAX6855UK43D2+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 4.300V reset threshold with 120ms typical reset timeout. It monitors VCC supply integrity, asserts reset during brownout or manual trigger, and guarantees valid reset operation down to VCC = +1.1V. Used in battery-powered medical and portable electronics for reliable power-on initialization and fault recovery.

For engineers reviewing the MAX6855UK43D2+T datasheet, MAX6855UK43D2+T pinout, MAX6855UK43D2+T application, or MAX6855UK43D2+T equivalent, key selection criteria include its 4.300V ±2.5% reset threshold, 120ms minimum timeout (D2 option), ultra-low 170nA typical supply current at 2.5V, and compatibility with 1.2V–5.5V VCC operation across –40°C to +85°C.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and reset timing control-without watchdog or CT functionality-into a single BiCMOS IC. Its active-high push-pull RESET output drives directly to VCC when asserted, eliminating external pull-up components, and remains valid even as VCC drops to 1.1V.

The reset logic responds to VCC falling below 4.300V (±2.5%), MR low pulse ≥1µs, or both; reset deassertion is delayed by the fixed D2 timeout (40–80ms min/typ/max) after VCC rises above threshold and MR releases. Immunity to short VCC transients (<40µs at 100mV overdrive) ensures robust operation in noisy environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT packages; thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6315US33D2+T, the MAX6855UK43D2+T delivers 7× lower supply current and a higher, adjustable 4.300V threshold-enabling tighter brownout detection in 5V-tolerant systems while extending battery runtime in portable medical devices.

Availability

MAX6855UK43D2+T is available at Aetrix Electronics and suitable for portable glucose monitors, patient vital sign loggers, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK43D2+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 communications markets.

The MAX6855UK43D2+T belongs to the MAX6854–MAX6869 nanopower supervisory family, engineered specifically for ultra-low-power battery-operated systems requiring guaranteed reset behavior across wide temperature and voltage ranges.

FAQ

What is the exact reset threshold voltage of the MAX6855UK43D2+T?

The MAX6855UK43D2+T has a factory-trimmed reset threshold of 4.300V with ±2.5% tolerance over –40°C to +85°C, as defined by the "43" suffix in its part number per Maxim's Threshold Suffix Guide. This value is measured at VCC falling and includes built-in hysteresis of 0.5% of VTH to prevent chatter near the trip point. The MAX6855UK43D2+T maintains this accuracy without external calibration.

Does the MAX6855UK43D2+T include a watchdog timer function?

No, the MAX6855UK43D2+T does not include a watchdog timer. Per Maxim's Selector Guide and Pin Description, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout logic. The MAX6855UK43D2+T is a dedicated voltage supervisor with manual reset (MR) and fixed reset timeout - confirmed by absence of WDI pin and lack of S/L suffix in its ordering code.

What is the reset timeout period for the MAX6855UK43D2+T?

The MAX6855UK43D2+T uses the D2 reset timeout option, providing a minimum of 40ms, typical of 60ms, and maximum of 80ms after VCC rises above 4.300V and MR is deasserted. This value is fixed per device configuration and is not pin-selectable - unlike MAX6861–MAX6863 which use the CT pin for timeout selection. The D2 timing ensures sufficient hold time for most 32-bit MCUs to complete internal initialization.

Can the MAX6855UK43D2+T operate with VCC below 1.2V?

Yes - the MAX6855UK43D2+T guarantees valid reset output down to VCC = +1.1V, as specified in Absolute Maximum Ratings and Electrical Characteristics. While the recommended operating range starts at 1.2V, the device continues asserting RESET correctly at 1.1V with ISOURCE = 10µA. Below 1.1V, reset behavior is not characterized; the MAX6855UK43D2+T is not intended for sub-1.1V operation.

Is the MAX6855UK43D2+T pin-compatible with other MAX68xx supervisory ICs?

The MAX6855UK43D2+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6866. However, it is not functionally pin-compatible with MAX6858/MAX6860 (which lack MR) or MAX6867–MAX6869 (which swap MR and WDI positions). Always verify signal mapping using the Pin Configurations diagram before board-level substitution.