Analog Devices Inc./Maxim Integrated MAX6855UK38D4+T

Overview

The MAX6855UK38D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing ultra-low 170nA typical supply current, factory-trimmed 3.800V reset threshold (±2.5%), and 1200ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and push-pull active-high RESET output - designed for reliable power-on reset and brownout protection in battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6855UK38D4+T datasheet, MAX6855UK38D4+T pinout, MAX6855UK38D4+T application, or MAX6855UK38D4+T equivalent, this device delivers guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients, and no external components required - key selection criteria for low-power embedded supervision where supply stability and quiescent current are design-defining.

Technical Context

The MAX6855UK38D4+T implements a precision bandgap-based voltage monitor with 2.5% threshold tolerance over -40°C to +85°C, paired with a digital timeout counter that holds RESET asserted for ≥1200ms after VCC rises above 3.800V and MR deasserts. Its MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection - enabling robust manual reset initiation without external RC networks.

This variant belongs to the MAX6854–MAX6869 family but excludes watchdog timer (WDI) and CT select functionality. It uses push-pull active-high RESET output referenced to VCC, ensuring clean logic-level compatibility with µP reset inputs requiring high-asserted reset signals during fault conditions.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), 2.9mm × 1.6mm × 1.1mm body, gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the MAX6855UK38D4+T, the TPS3837K33DBVR offers lower cost but sacrifices nanopower operation and threshold flexibility, while the MAX6316LUK38D4+T provides identical supervision specs with inverted reset polarity - enabling reuse of the same timing and threshold design in active-low reset systems.

Availability

MAX6855UK38D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and MP3 players requiring stable component supply with long-term lifecycle support and lead-free compliance.

Supply support for MAX6855UK38D4+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 management, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6854–MAX6869 product line delivers nanopower supervisory circuits optimized for battery longevity and reliability in portable medical and handheld electronics - emphasizing sub-µA ICC, wide VCC operating range, and robust reset timing.

FAQ

What is the exact reset threshold voltage of the MAX6855UK38D4+T?

The MAX6855UK38D4+T has a factory-trimmed reset threshold voltage of 3.800V with ±2.5% tolerance over -40°C to +85°C, corresponding to the "38" suffix per Maxim's Threshold Suffix Guide. This value is guaranteed by design and tested across temperature and voltage ranges - not derived from typical curves or interpolation. The MAX6855UK38D4+T maintains reset validity down to VCC = +1.1V, making it suitable for deep brownout detection in battery-powered systems.

Does the MAX6855UK38D4+T include a watchdog timer function?

No, the MAX6855UK38D4+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset (MR) functionality. Watchdog timer capability is exclusive to MAX6864–MAX6869 variants (denoted by "S" or "L" suffixes in ordering code). The MAX6855UK38D4+T pinout lacks WDI, and its functional diagram confirms absence of watchdog circuitry - confirming it is a dedicated voltage supervisor without timer-based reset.

What is the RESET output configuration of the MAX6855UK38D4+T?

The MAX6855UK38D4+T features a push-pull active-high RESET output, meaning it drives high during reset assertion and low when deasserted. This differs from open-drain or active-low variants and eliminates the need for an external pullup resistor. The output is referenced to VCC, with VOH ≥0.8×VCC at 500µA source current and VOL ≤0.3V at 1.2mA sink current - ensuring reliable interfacing with standard CMOS µP reset inputs. This configuration is confirmed in the MAX6855-specific pin description and Selector Guide.

How does the 1200ms reset timeout period of the MAX6855UK38D4+T benefit system design?

The 1200ms minimum reset timeout period of the MAX6855UK38D4+T ensures the host microprocessor completes full power-up initialization, clock stabilization, and peripheral configuration before release from reset - critical for systems with slow-starting regulators or complex boot sequences. This timeout corresponds to the "D4" option per Table 4 and is guaranteed over temperature and voltage. Unlike adjustable timeouts, D4 provides deterministic timing without external components, simplifying qualification and eliminating drift-related field failures in medical and industrial applications.

Is the MAX6855UK38D4+T pin-compatible with other devices in the MAX68xx family?

The MAX6855UK38D4+T shares the same 5-pin SOT23 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6869 - but functional compatibility depends on reset polarity and feature set. While physically interchangeable, substituting with a MAX6854 (active-low) or MAX6864 (with WDI) would require schematic and firmware changes. The MAX6855UK38D4+T is functionally pin-compatible only with other MAX6855 variants sharing the same threshold and timeout suffixes.