Analog Devices Inc./Maxim Integrated MAX6855UK42D3+T

Overview

The MAX6855UK42D3+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 4.200V reset threshold (±2.5%), and a 150ms minimum reset timeout period. It provides active-high push-pull RESET output, manual reset input (MR), and operates across -40°C to +85°C for reliable power-up/brownout monitoring in battery-powered medical and portable electronics.

For engineers reviewing the MAX6855UK42D3+T datasheet, MAX6855UK42D3+T pinout, MAX6855UK42D3+T application, or MAX6855UK42D3+T equivalent, this device serves as a low-quiescent-current voltage monitor with deterministic reset timing, MR-initiated recovery, and guaranteed RESET validity down to VCC = +1.1V - critical for glucose monitors, patient monitors, and energy-constrained embedded systems.

Technical Context

The MAX6855UK42D3+T implements a precision bandgap-based voltage comparator with hysteresis (0.5% of VTH) to detect VCC falling below 4.200V, triggering an active-high push-pull RESET assertion. Its internal timer enforces a minimum 150ms reset pulse width after VCC recovers above threshold or MR deasserts.

It integrates a 10kΩ internal MR pullup, supports CMOS-logic-compatible MR input (VIH = 0.7×VCC, VIL = 0.3×VCC), and guarantees valid operation with supply voltages from 1.2V to 5.5V - enabling use in 1.8V, 2.5V, 3.3V, and 5V systems without external level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6369KA29D3+T, the MAX6855UK42D3+T delivers 7× lower supply current, precise 4.200V threshold matching Li-ion full-charge voltage, and integrated MR support - making it optimal for long-life, single-cell battery systems where reset polarity and ultra-low ICC are critical.

Availability

MAX6855UK42D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and MP3 players requiring stable component supply, long-term lifecycle support, and RoHS-compliant lead-free packaging.

Supply support for MAX6855UK42D3+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 MAX6855UK42D3+T belongs to the MAX6854–MAX6869 nanopower supervisory family, engineered specifically for ultra-low-power, battery-critical systems where sub-µA quiescent current and guaranteed reset behavior down to 1.1V are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6855UK42D3+T?

The MAX6855UK42D3+T has a factory-trimmed reset threshold of 4.200V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "42" corresponds to VTH = 4.200V. The MAX6855UK42D3+T uses this precise threshold to monitor Li-ion battery full-charge voltage and ensure clean reset during discharge transitions.

Does the MAX6855UK42D3+T include a watchdog timer function?

No, the MAX6855UK42D3+T does not include a watchdog timer. Per the Selector Guide and Pin Configurations, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK42D3+T is a manual-reset-only supervisory circuit with MR input and active-high push-pull RESET. Its functional scope is limited to voltage monitoring and MR-initiated reset - no watchdog logic or timeout supervision is present in the MAX6855UK42D3+T.

What is the reset timeout period for the MAX6855UK42D3+T?

The MAX6855UK42D3+T has a minimum reset timeout period of 150ms, indicated by the "D3" suffix in its part number. This value is specified in Table 4 (Reset Timeout Periods) as D3 = 150ms (min), 225ms (typ), 300ms (max). The timeout begins after VCC rises above 4.200V or MR is released, ensuring sufficient time for microprocessor initialization before release from reset.

Can the MAX6855UK42D3+T operate with a 1.8V supply?

Yes, the MAX6855UK42D3+T operates with supply voltages from 1.2V to 5.5V, fully specified across that range. At 1.8V, its supply current remains at 170nA typical, and RESET output meets VOH ≥ 0.8×VCC (≥1.44V) and VOL ≤ 0.3V when sinking 200µA. This makes the MAX6855UK42D3+T suitable for direct integration into 1.8V logic domains without level translation.

Is the MAX6855UK42D3+T pin-compatible with other supervisory ICs?

The MAX6855UK42D3+T is pin-compatible with the TPS3836/TPS3837/TPS3838 series per the datasheet's Features section, sharing identical 5-pin SOT23 pinout (VCC, GND, MR, GND, RESET). However, note that RESET polarity differs: MAX6855UK42D3+T provides active-high push-pull output, whereas TPS3837 offers active-low open-drain - requiring schematic review before substitution.