Analog Devices Inc./Maxim Integrated MAX6855UK24D4+T

Overview

The MAX6855UK24D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and active-low push-pull reset output. It asserts reset when VCC drops below 2.400V (±2.5%), MR is pulled low, or during power-up/brownout - with guaranteed reset validity down to VCC = +1.1V and ultra-low 170nA typical supply current. It is used in battery-powered glucose monitors and portable medical devices requiring reliable, low-power system initialization.

For engineers reviewing the MAX6855UK24D4+T datasheet, MAX6855UK24D4+T pinout, MAX6855UK24D4+T application, or MAX6855UK24D4+T equivalent, key selection criteria include its factory-trimmed 2.4V reset threshold, 1200ms minimum reset timeout, -40°C to +85°C operating range, push-pull active-high RESET output, and immunity to short VCC transients - all critical for low-voltage, long-battery-life embedded systems.

Technical Context

This device integrates a precision voltage monitor with hysteresis (0.5% of VTH), a fixed 1200ms reset timeout timer, and a CMOS-compatible manual reset input with 10kΩ internal pullup and 1µs minimum pulse width. Its reset assertion logic ensures deterministic behavior during VCC ramp-up and brownout recovery, with tRD < 40µs and guaranteed reset deassertion only after VCC exceeds VTH + 150mV.

The MAX6855UK24D4+T features an active-high push-pull RESET output referenced to VCC, delivering VOH ≥ 0.8×VCC at ISOURCE = 500µA (VCC ≥ 2.38V) and VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V). It operates across 1.2V–5.5V supply range and remains functional down to VCC = 1.1V, enabling use in ultra-low-voltage microcontroller systems.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), 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 TPS3837K24 and ADM6805-24ARTZ-RL, the MAX6855UK24D4+T uniquely combines ultra-low 170nA current, 1200ms timeout, and active-high push-pull output - eliminating external components while supporting deep-brownout resilience down to 1.1V, making it optimal for battery-critical medical and portable electronics.

Availability

MAX6855UK24D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and PDAs requiring stable component supply with long-term lifecycle support and RoHS-compliant packaging.

Supply support for MAX6855UK24D4+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 industrial, medical, and communications applications.

The MAX6855UK24D4+T belongs to the MAX68xx nanopower µP supervisory family, engineered specifically for ultra-low-power, battery-operated medical and portable electronics requiring guaranteed reset integrity across wide temperature and voltage ranges.

FAQ

What is the exact reset threshold voltage of the MAX6855UK24D4+T?

The MAX6855UK24D4+T has a factory-trimmed reset threshold of 2.400V with ±2.5% tolerance over -40°C to +85°C, as specified in Table 2 (Threshold Suffix Guide) of the datasheet. This value is laser-trimmed during production and does not require external calibration. The '24' in the part number explicitly denotes the 2.4V threshold variant, and the MAX6855UK24D4+T maintains this accuracy across its full operating voltage range (1.2V–5.5V) and temperature range.

Does the MAX6855UK24D4+T include a watchdog timer function?

No, the MAX6855UK24D4+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog functionality. The MAX6855UK24D4+T is a manual-reset-only supervisory circuit with MR input and voltage monitoring - confirmed by its pinout (no WDI pin) and absence of watchdog timing parameters in its electrical characteristics table.

What is the reset output configuration of the MAX6855UK24D4+T?

The MAX6855UK24D4+T provides an active-high push-pull reset output on Pin 1. As documented in the MAX6854/MAX6855/MAX6856 Pin Description table, the MAX6855 variant uses Pin 1 for RESET (active-high push-pull), unlike the MAX6854 (open-drain/push-pull active-low) or MAX6856 (open-drain active-low). This configuration eliminates the need for an external pullup resistor and allows direct connection to microcontrollers requiring active-high reset signals.

What is the minimum reset timeout period for the MAX6855UK24D4+T?

The MAX6855UK24D4+T has a minimum reset timeout period of 1200ms, indicated by the 'D4' suffix in its part number per Table 4 (Reset Timeout Periods). This value is guaranteed across -40°C to +85°C and represents the shortest duration the RESET signal remains asserted after VCC rises above the 2.4V threshold or MR is deasserted - sufficient for complex bootloader execution in modern low-power µPs.

Is the MAX6855UK24D4+T compatible with 1.8V microcontroller systems?

Yes, the MAX6855UK24D4+T is fully compatible with 1.8V systems: it operates from 1.2V to 5.5V, draws only 170nA typical supply current at VCC = 1.8V, and guarantees valid RESET output down to VCC = 1.1V. Its push-pull active-high RESET output delivers VOH ≥ 0.8×VCC (≥1.44V) at ISOURCE = 500µA, meeting standard 1.8V CMOS input high-level requirements, making it ideal for ultra-low-voltage wearable and sensor applications.