Analog Devices Inc./Maxim Integrated MAX6855UK42D2+T

Overview

The MAX6855UK42D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and push-pull active-high RESET output. It asserts reset when VCC drops below 4.200V (±2.5%), MR is pulled low, or during power-up/brownout - with guaranteed reset validity down to VCC = +1.1V. Designed for ultra-low-power portable medical and consumer devices like glucose monitors and MP3 players.

For engineers reviewing the MAX6855UK42D2+T datasheet, MAX6855UK42D2+T pinout, MAX6855UK42D2+T application, or MAX6855UK42D2+T equivalent, key selection criteria include its 4.200V factory-trimmed threshold, 40ms minimum reset timeout, 170nA typical supply current at 2.5V, and immunity to short VCC transients - all critical for battery-powered system reliability and low-quiescent design.

Technical Context

This device integrates a precision bandgap-based voltage detector, a digital reset timeout timer, and an internal 10kΩ MR pullup resistor. Its reset assertion logic combines VCC monitoring with asynchronous MR input, ensuring deterministic behavior across -40°C to +85°C without external components.

The push-pull active-high RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC (at ISOURCE = 500µA) and VOL ≤ 0.3V (at ISINK = 1.2mA), enabling direct interfacing with 1.8V–5.5V µP reset inputs while maintaining valid logic levels down to VCC = 1.1V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact footprint (2.9mm × 1.6mm × 1.1mm) optimized 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 TPS3837K33DBVR and MAX6361KA29D3+T, the MAX6855UK42D2+T delivers 7× lower supply current and integrated MR functionality - making it uniquely suitable for 4.2V Li-ion–powered portable medical devices requiring long-term autonomy and operator-initiated reset capability.

Availability

MAX6855UK42D2+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and smart pagers requiring stable component supply across extended production lifecycles and global regulatory compliance.

Supply support for MAX6855UK42D2+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6855UK42D2+T belongs to the MAX6854–MAX6869 nanopower supervisory family, engineered specifically for ultra-low-current battery-powered systems where reset accuracy, long service life, and minimal board space are critical.

FAQ

What is the exact reset threshold voltage of the MAX6855UK42D2+T?

The MAX6855UK42D2+T has a factory-trimmed reset threshold voltage of 4.200V 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 "42" corresponds to 4.200V nominal. The MAX6855UK42D2+T maintains this accuracy without external calibration.

Does the MAX6855UK42D2+T include a watchdog timer function?

No, the MAX6855UK42D2+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK42D2+T is a manual-reset-only supervisory circuit with MR and VCC monitoring. Its part number lacks a watchdog suffix (e.g., "S" or "L"), confirming absence of watchdog functionality.

What is the reset timeout period for the MAX6855UK42D2+T?

The MAX6855UK42D2+T has a minimum reset timeout period of 40ms, indicated by the "D2" suffix in its part number. Table 4 (Reset Timeout Periods) specifies D2 as 40ms (min) / 60ms (typ) / 80ms (max). This timeout begins after VCC rises above 4.200V and MR is deasserted, ensuring sufficient time for µP power stabilization.

Is the MAX6855UK42D2+T pin-compatible with other MAX68xx devices?

The MAX6855UK42D2+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6869. However, output polarity differs: MAX6855UK42D2+T provides active-high push-pull RESET, whereas MAX6854/MAX6856 offer active-low variants - requiring schematic review before substitution.

What is the maximum operating temperature range for the MAX6855UK42D2+T?

The MAX6855UK42D2+T is rated for operation from -40°C to +85°C, as specified in the Ordering Information table and Absolute Maximum Ratings section. This industrial temperature range is validated across all electrical characteristics, including reset threshold accuracy, supply current, and timeout timing, ensuring reliability in portable medical and consumer equipment.