Analog Devices Inc./Maxim Integrated MAX6855UK23D4+T

Overview

The MAX6855UK23D4+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 2.313V reset threshold (suffix "23"), and a 1200ms minimum reset timeout (suffix "D4"). It provides active-high push-pull RESET output, manual reset input (MR), and operates across –40°C to +85°C for battery-powered medical and portable electronics.

For engineers reviewing the MAX6855UK23D4+T datasheet, MAX6855UK23D4+T pinout, MAX6855UK23D4+T application, or MAX6855UK23D4+T equivalent, this device is selected for low-power brownout detection, manual system recovery, and deterministic reset timing in space-constrained, long-life embedded systems where VCC monitoring down to 1.1V and transient immunity are critical.

Technical Context

This IC integrates voltage monitoring, manual reset assertion, and reset timeout generation - but excludes watchdog timer and CT-selectable delay functions. Its internal comparator continuously monitors VCC against a precision 2.313V threshold, triggering an active-high RESET signal when VCC falls below that level or MR is pulled low.

The reset remains asserted for ≥1200ms after VCC rises above threshold and MR deasserts, with guaranteed valid operation down to VCC = 1.1V. The push-pull output drives high to VCC (≥0.8×VCC at 500µA source) and low to ≤0.3V (at 1.2mA sink), eliminating external pull-up components.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (RoHS-compliant), 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6855UK23D4+T, the MAX6854UK23D4+T offers open-drain flexibility at the cost of added component count, while the TPS3836K23DBVR trades nanopower efficiency for broader vendor support and simplified qualification - making MAX6855UK23D4+T optimal for ultra-long-life, space-constrained medical wearables.

Availability

MAX6855UK23D4+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and low-power wearable sensors requiring stable component supply across extended product lifecycles.

Supply support for MAX6855UK23D4+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 MAX685x family delivers nanopower supervisory functionality for battery-critical systems - engineered specifically for reliable reset generation in glucose meters, portable diagnostics, and implant-adjacent wearables where micropower and voltage accuracy are non-negotiable.

FAQ

What is the exact reset threshold voltage of the MAX6855UK23D4+T?

The MAX6855UK23D4+T has a factory-trimmed reset threshold voltage of 2.313V, with ±2.5% tolerance over –40°C to +85°C. This value is defined by the "23" suffix per Maxim's Threshold Suffix Guide (Table 2), and is verified in the Electrical Characteristics table under VTH parameter. The MAX6855UK23D4+T uses this precise threshold to detect brownout on 2.4V nominal rails common in Li-ion-powered medical devices.

Does the MAX6855UK23D4+T include a watchdog timer function?

No, the MAX6855UK23D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description tables, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout logic. The MAX6855UK23D4+T belongs to the MAX6854/MAX6855/MAX6856 group, which provides voltage monitoring, manual reset (MR), and fixed reset timeout - but no watchdog capability. Its pinout lacks WDI, confirming this functional boundary.

What is the purpose of the dual GND pins (pins 2 and 4) on the MAX6855UK23D4+T?

The MAX6855UK23D4+T uses two dedicated GND pins (pins 2 and 4) to reduce ground impedance and improve noise immunity in sensitive analog monitoring paths. This dual-ground structure minimizes voltage drop across bond wires during reset assertion and stabilizes the internal voltage reference, ensuring accurate 2.313V threshold detection even in electrically noisy portable equipment. It also aids thermal dissipation in the 5-pin SOT23 package.

Can the MAX6855UK23D4+T operate reliably below 1.2V supply voltage?

The MAX6855UK23D4+T is specified to operate down to VCC = 1.2V per Absolute Maximum Ratings and Electrical Characteristics tables. While its reset output is *guaranteed valid* down to 1.1V, functional operation (e.g., MR detection, timeout timing) is only characterized from 1.2V. Below 1.2V, behavior is not tested or guaranteed - so system design must ensure VCC stays ≥1.2V during active supervision, with 1.1V serving only as a fail-safe assertion floor.

How does the MR input of the MAX6855UK23D4+T interface with a mechanical pushbutton?

The MAX6855UK23D4+T MR input features an internal 10kΩ pullup to VCC, allowing direct connection of a normally-open momentary switch between MR (pin 3) and GND. No external resistor or debounce circuitry is needed - the device's 200ns MR glitch rejection and 250ns MR-to-reset delay ensure clean, bounce-free reset assertion. This simplifies front-panel recovery design in handheld medical tools using the MAX6855UK23D4+T.