Analog Devices Inc./Maxim Integrated MAX6855UK25D1+T

Overview

The MAX6855UK25D1+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 2.5V reset threshold with ±2.5% tolerance. It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), and guarantees valid reset down to VCC = +1.1V. It delivers ultra-low 170nA typical supply current and supports 10ms minimum reset timeout - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6855UK25D1+T datasheet, MAX6855UK25D1+T pinout, MAX6855UK25D1+T application, or MAX6855UK25D1+T equivalent, key selection criteria include its active-high push-pull RESET logic, 2.5V threshold accuracy over -40°C to +85°C, immunity to sub-40µs VCC transients, and compatibility with low-voltage µP reset inputs requiring guaranteed assertion below 1.2V.

Technical Context

The MAX6855UK25D1+T implements a precision bandgap-based voltage monitor with hysteresis (0.5% of VTH) and an internal RC-timed reset delay generator. Its MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection - enabling direct connection to momentary switches without external debounce.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6855UK25D1+T omits WDI and CT pins, simplifying design for applications where only power-monitoring and manual reset are required. Its push-pull active-high RESET output drives directly into CMOS µP reset inputs without external pullup, sinking ≤0.3V at 1.2mA (VCC ≥ 2.38V) and sourcing ≥0.8×VCC at 500µA.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K25DBVR and MAX6315US25D3+, the MAX6855UK25D1+T uniquely combines 2.5V threshold, 10ms timeout, active-high push-pull output, and nanopower 170nA ICC - making it optimal for space- and energy-constrained medical wearables where reset polarity and battery longevity are critical.

Availability

MAX6855UK25D1+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and wireless pulse oximeters requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK25D1+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 MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer electronics, prioritizing nanoscale ICC, wide VCC range, and robust reset timing integrity.

FAQ

What is the reset threshold voltage and tolerance for MAX6855UK25D1+T?

The MAX6855UK25D1+T has a factory-trimmed reset threshold of 2.5V with a tolerance of ±2.5% over the full -40°C to +85°C operating temperature range. This value is confirmed in the Electrical Characteristics table under "VCC Reset Threshold (VTH)" and corresponds to the "25" suffix in the part number. The MAX6855UK25D1+T guarantees reliable brownout detection at 2.5V nominal rails while accommodating process and temperature variation.

Does MAX6855UK25D1+T include a watchdog timer function?

No, the MAX6855UK25D1+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset functionality. Watchdog capability is exclusive to the MAX6864–MAX6869 variants (e.g., MAX6864UK25D1S+T), which add the WDI pin and selectable watchdog timeout. The MAX6855UK25D1+T pinout omits WDI and contains only VCC, GND×2, MR, and RESET.

What is the reset timeout period configured for MAX6855UK25D1+T?

The "D1" suffix in MAX6855UK25D1+T specifies a minimum reset timeout period of 10ms. Per Table 4 (Reset Timeout Periods), D1 offers min/typ/max values of 10ms/15ms/25ms. This short timeout enables rapid system recovery after brief power disturbances - critical in responsive portable medical devices where extended reset hold times would degrade user experience.

What type of reset output does MAX6855UK25D1+T provide?

The MAX6855UK25D1+T provides a push-pull active-high RESET output, as confirmed by the Selector Guide and Pin Description tables. When asserted (during VCC brownout or MR activation), RESET goes low; upon deassertion, it drives high to VCC. This eliminates the need for an external pullup resistor and ensures clean, rail-to-rail logic levels compatible with standard CMOS µP reset inputs requiring active-high assertion.

Is MAX6855UK25D1+T compatible with 1.8V microcontrollers?

Yes, the MAX6855UK25D1+T operates down to VCC = 1.2V and guarantees valid reset assertion down to VCC = 1.1V, making it fully compatible with 1.8V µCs. Its push-pull active-high RESET output sources ≥0.8×VCC at 500µA when deasserted, ensuring sufficient drive strength at 1.8V. Additionally, MR input thresholds scale with VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), supporting direct interfacing with 1.8V GPIO.