Analog Devices Inc./Maxim Integrated MAX6855UK31D4+T

Overview

MAX6855UK31D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, providing active-high push-pull reset output, manual reset input (MR), and factory-trimmed 3.075V reset threshold (suffix "31"). It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), with 1200ms minimum reset timeout (suffix "D4") and ultra-low 170nA typical supply current. It is used in battery-powered glucose monitors and portable medical devices requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6855UK31D4+T datasheet, MAX6855UK31D4+T pinout, MAX6855UK31D4+T application, or MAX6855UK31D4+T equivalent, this page delivers verified functional identity, exact pin roles, confirmed reset timing behavior, true alternative part comparisons, and design-meaningful specifications - all extracted from Maxim's official 19-3139 Rev 4 datasheet and validated against ordering information and pin configuration diagrams.

Technical Context

The MAX6855UK31D4+T implements a voltage-monitoring supervisory architecture with internal bandgap reference and precision comparator for reset assertion at VCC falling below 3.075V ±2.5%. Its active-high push-pull RESET output is referenced to VCC and guarantees VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA) across 1.2V–5.5V VCC range.

It features a dedicated MR input with 10kΩ internal pullup, 1µs minimum pulse width, and 250ns MR-to-reset delay. Unlike MAX6864–MAX6869 variants, it lacks watchdog timer (WDI) or CT timeout-select functionality - confirmed by Selector Guide and Pin Description tables showing no WDI or CT pin assignment for MAX6855.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (lead-free, +T suffix), 2.9mm × 1.6mm footprint, 1.1mm height - compatible with standard high-volume pick-and-place assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6315US31D3+T, the MAX6855UK31D4+T provides 70× lower supply current and 8× longer reset timeout while delivering active-high push-pull drive - making it uniquely suited for long-life, high-reliability medical wearables where reset timing margin and energy efficiency are non-negotiable.

Availability

MAX6855UK31D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and handheld medical diagnostics requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK31D4+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 medical and portable equipment - prioritizing nanoscale current consumption, guaranteed reset validity at ultra-low VCC, and minimal external component count.

FAQ

What is the exact reset threshold voltage of MAX6855UK31D4+T?

The MAX6855UK31D4+T has a factory-trimmed reset threshold of 3.075V ±2.5%, as defined by the "31" suffix in its part number per Table 2 (Threshold Suffix Guide). This value is guaranteed over -40°C to +85°C and enables precise brownout detection for 3.3V systems without external adjustment. The MAX6855UK31D4+T datasheet specifies VTH = 3.075V (typ) with hysteresis of 0.5% of VTH.

Does MAX6855UK31D4+T include a watchdog timer function?

No, the MAX6855UK31D4+T does not include a watchdog timer. Per the Selector Guide and Pin Configuration diagrams, MAX6855 is explicitly listed without WDI (Watchdog Input) functionality. Only MAX6864–MAX6869 variants incorporate watchdog circuitry; the MAX6855UK31D4+T provides voltage monitoring and manual reset only - confirmed by absence of WDI pin and watchdog-related electrical characteristics in its datasheet section.

What is the function of Pin 4 on MAX6855UK31D4+T?

Pin 4 on the MAX6855UK31D4+T is a second GND terminal, electrically tied to Pin 2 internally. Its inclusion improves noise immunity and reduces ground impedance in high-density PCB layouts. This dual-GND configuration is standard for MAX6854/MAX6855/MAX6856 variants in SOT23-5 package and is documented in the "MAX6854/MAX6855/MAX6856 Pin Description" table on page 7 of the datasheet.

Can MAX6855UK31D4+T drive an active-high reset input directly?

Yes, the MAX6855UK31D4+T features an active-high push-pull RESET output (Pin 1) that drives high during reset assertion and low when deasserted - eliminating need for external pullup resistors. It guarantees VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA, making it fully compatible with standard active-high µP reset inputs such as those on STM32L4 or nRF52 series MCUs.

What is the minimum MR pulse width required to trigger reset on MAX6855UK31D4+T?

The MAX6855UK31D4+T requires a minimum MR pulse width of 1µs to reliably assert reset, as specified in the Electrical Characteristics table under "MR Minimum Pulse Width (tMPW)". The device also provides 200ns glitch rejection, ensuring noise spikes shorter than 200ns do not cause unintended resets. This timing is validated across -40°C to +85°C and enables robust manual reset implementation with mechanical switches or digital control signals.