Analog Devices Inc./Maxim Integrated MAX6855UK25D2+T

Overview

The MAX6855UK25D2+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 delivers ultra-low 170nA typical supply current, guarantees valid reset assertion down to VCC = +1.1V, and provides a 40ms minimum reset timeout period. It is designed for reliable power-on reset and brownout protection in battery-critical portable systems.

For engineers reviewing the MAX6855UK25D2+T datasheet, MAX6855UK25D2+T pinout, MAX6855UK25D2+T application, or MAX6855UK25D2+T equivalent, key selection criteria include its 2.5V reset threshold accuracy, 40ms reset timeout, active-high push-pull output logic, MR-driven reset initiation, and immunity to sub-40µs VCC transients - all critical for low-power embedded reset integrity.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and deterministic reset timing into a single die. Its internal comparator continuously monitors VCC against a precision bandgap-derived 2.5V threshold, while the MR input allows external reset triggering with 10kΩ internal pullup and 250ns MR-to-reset delay.

The reset state machine asserts RESET high when VCC falls below 2.5V or MR is pulled low, holding it high for ≥40ms after VCC rises above threshold and MR deasserts. No watchdog timer or CT pin functionality is present - confirming MAX6855UK25D2+T as a dedicated voltage-monitoring + MR supervisory IC without timeout select or watchdog features.

Key Specifications

Pinout & Package

MAX6855UK25D2+T is housed in a lead-free 5-pin SOT23-5 package (JEDEC MO-178AA), with 1.3mm height and 2.9mm × 1.6mm footprint - optimized for space-constrained portable PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K25DBVR and ADM6805S25ARTZ-RL, the MAX6855UK25D2+T uniquely combines ultra-low 170nA ICC, precise 2.5V threshold, 40ms timeout, and active-high push-pull output - making it the optimal choice for battery-powered devices demanding minimal power and direct µP interface without external components.

Availability

MAX6855UK25D2+T is available at Aetrix Electronics and suitable for portable medical sensors, low-power IoT edge nodes, wearable fitness bands, and industrial handheld scanners requiring stable component supply and long-term lifecycle support.

Supply support for MAX6855UK25D2+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX685x family was engineered specifically for nanopower microprocessor supervision in battery-constrained systems - delivering precision voltage monitoring, manual reset, and deterministic timing in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6855UK25D2+T?

The MAX6855UK25D2+T has a factory-trimmed reset threshold of 2.500V with ±2.5% tolerance over the full -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "25" corresponds to 2.5V nominal. The actual device will assert reset when VCC falls below this threshold during power-down or brownout events.

Does the MAX6855UK25D2+T include a watchdog timer function?

No, the MAX6855UK25D2+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout capability. The MAX6855UK25D2+T is a dedicated voltage monitor + manual reset IC with no watchdog circuitry - confirmed by absence of WDI pin and related timing parameters in its electrical characteristics table.

What is the reset timeout period for the MAX6855UK25D2+T?

The MAX6855UK25D2+T has a 40ms minimum reset timeout period, indicated by the "D2" suffix in its part number. This is verified in Table 4 (Reset Timeout Periods), where D2 corresponds to 40ms (min), 60ms (typ), and 80ms (max). The internal timer holds RESET high for ≥40ms after VCC rises above 2.5V and MR is deasserted, ensuring sufficient hold time for microcontroller initialization.

Is the MAX6855UK25D2+T pin-compatible with other MAX685x series devices?

The MAX6855UK25D2+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6869 variants. However, output logic differs: MAX6855UK25D2+T uses active-high push-pull, while MAX6854 uses active-low push-pull and MAX6856 uses active-low open-drain - requiring schematic review before substitution.

What is the maximum VCC transient duration the MAX6855UK25D2+T can ignore?

The MAX6855UK25D2+T is immune to VCC transients ≤40µs in duration when the overdrive is 100mV (i.e., VCC dips 100mV below the 2.5V threshold), as shown in Figure MAX684 toc05. This immunity prevents false resets caused by brief supply noise from switching regulators or digital switching, ensuring robust operation in electrically noisy portable environments.