Analog Devices Inc./Maxim Integrated MAX6855UK37D5+T

Overview

MAX6855UK37D5+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring active-high push-pull reset output, 3.7V factory-trimmed reset threshold (±2.5%), 450ms minimum reset timeout, manual reset input (MR), and guaranteed reset validity down to VCC = +1.1V. It monitors supply voltage in ultra-low-power systems such as glucose monitors and portable medical devices.

For engineers reviewing the MAX6855UK37D5+T datasheet, MAX6855UK37D5+T pinout, MAX6855UK37D5+T application, or MAX6855UK37D5+T equivalent, key selection criteria include its 170nA typical supply current, immunity to short VCC transients, no external components requirement, and compatibility with battery-powered designs requiring long-term reliability and brownout protection.

Technical Context

The MAX6855UK37D5+T implements a precision bandgap-based voltage monitor with 2.5% threshold accuracy over –40°C to +85°C, combined with a monolithic reset timeout generator and internal 10kΩ MR pullup. Its active-high push-pull RESET output drives directly to VCC without external biasing.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), this part lacks WDI functionality and CT select input-its reset timeout is fixed at 450ms (D5 option) and threshold is permanently set to 3.700V (suffix "37"). It asserts RESET high when VCC falls below VTH or MR is pulled low, holding assertion for ≥450ms after recovery.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact footprint (2.9mm × 1.6mm × 1.1mm) suitable for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6315US37D3+T, the MAX6855UK37D5+T delivers 10× lower supply current, longer 450ms reset hold time for robust boot sequencing, and active-high push-pull output eliminating external biasing-making it optimal for long-life, single-supply medical and portable electronics.

Availability

MAX6855UK37D5+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and MP3 players requiring stable component supply with long-term lifecycle support and traceable sourcing.

Supply support for MAX6855UK37D5+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 and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6854–MAX6869 family targets ultra-low-power microprocessor supervision in battery-critical systems, emphasizing nanopower operation, factory-trimmed accuracy, and minimal external component count.

FAQ

What is the reset threshold voltage of the MAX6855UK37D5+T?

The MAX6855UK37D5+T has a factory-trimmed reset threshold voltage of 3.700V with ±2.5% tolerance over –40°C to +85°C. This value is encoded in the "37" suffix per Table 2 of the datasheet and is optimized for monitoring 3.7V Li-ion battery rails or 3.3V systems with margin. The MAX6855UK37D5+T guarantees valid reset assertion down to VCC = +1.1V.

Does the MAX6855UK37D5+T include a watchdog timer function?

No, the MAX6855UK37D5+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset functions. Watchdog capability is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UKxxDxxS+T). The MAX6855UK37D5+T pinout lacks WDI, confirming absence of watchdog circuitry.

What is the reset timeout period for the MAX6855UK37D5+T?

The MAX6855UK37D5+T features a fixed minimum reset timeout period of 450ms, indicated by the "D5" suffix in its part number. This value is guaranteed across temperature and supply voltage per Table 4 of the datasheet. The timeout begins after VCC rises above the 3.7V threshold or MR deasserts, and ensures sufficient duration for µP initialization sequences.

What type of reset output does the MAX6855UK37D5+T provide?

The MAX6855UK37D5+T provides an active-high push-pull reset output on Pin 1. Unlike open-drain variants, it sources current when asserted (RESET = high) and sinks current when deasserted (RESET = low), eliminating the need for an external pullup resistor. This output is referenced to VCC and complies with standard CMOS logic thresholds.

Can the MAX6855UK37D5+T operate from a 1.8V supply?

Yes, the MAX6855UK37D5+T operates from VCC = 1.2V to 5.5V, including 1.8V. At 1.8V, its typical supply current is 170nA, and RESET output specifications (VOH/VOL) remain valid per Electrical Characteristics table. Its 3.7V threshold is independent of VCC - meaning it monitors a separate higher-voltage rail while being powered from 1.8V, provided VCC ≥ 1.2V.