Analog Devices Inc./Maxim Integrated MAX6855UK38D2+T

Overview

The MAX6855UK38D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and active-low push-pull reset output. It asserts reset when VCC drops below 3.705V (typ), MR is pulled low, or during power-up/brownout - with guaranteed reset validity down to VCC = +1.1V and ultra-low 170nA typical supply current. It serves as a critical power-on reset and fault recovery element in battery-powered medical and portable electronics.

For engineers reviewing the MAX6855UK38D2+T datasheet, MAX6855UK38D2+T pinout, MAX6855UK38D2+T application, or MAX6855UK38D2+T equivalent, this page delivers verified functional identity, exact reset threshold (3.705V), timeout (40ms min), MR timing behavior, push-pull RESET logic polarity, and validated alternatives for low-power µP supervision in space- and energy-constrained designs.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold accuracy over –40°C to +85°C, coupled to a digital timeout counter that holds RESET asserted for ≥40ms after VCC rises above threshold and MR deasserts. Its MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 250ns MR-to-reset delay - enabling direct interface with momentary switches or CMOS logic without external components.

The push-pull active-high RESET output drives high (≥0.8×VCC) when asserted and low (≤0.3V) when deasserted, referenced to VCC, eliminating need for external pullups. Immunity to short VCC transients (e.g., ≤40µs at 100mV overdrive) ensures robust operation in noisy power environments typical of portable systems.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6361LUR29+T, the MAX6855UK38D2+T offers 10× lower supply current, precise 3.705V threshold for 3.3V/3.6V systems, and active-high push-pull output - making it uniquely suited for long-life, space-constrained portable medical devices where every nanoamp and millivolt matters.

Availability

MAX6855UK38D2+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and PDAs requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6855UK38D2+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 portable applications.

The MAX685x family was designed specifically for ultra-low-power microprocessor supervision in battery-operated medical and consumer devices, emphasizing nanoscale current consumption, precise voltage thresholds, and minimal external component count.

FAQ

What is the exact reset threshold voltage of the MAX6855UK38D2+T?

The MAX6855UK38D2+T has a factory-trimmed reset threshold voltage of 3.705V (typical), with ±2.5% tolerance over –40°C to +85°C. This value corresponds to the "38" suffix in the part number per Maxim's Threshold Suffix Guide (Table 2), and is optimized for reliable supervision of 3.3V and 3.6V power rails in portable equipment. The MAX6855UK38D2+T guarantees valid reset assertion down to VCC = +1.1V.

Does the MAX6855UK38D2+T include a watchdog timer function?

No, the MAX6855UK38D2+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides voltage monitoring and manual reset (MR) only. Watchdog functionality is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UK38D2S+T). The MAX6855UK38D2+T pinout lacks WDI, and its functional diagram confirms absence of watchdog circuitry.

What is the reset timeout period for the MAX6855UK38D2+T?

The MAX6855UK38D2+T has a reset timeout period of 40ms (minimum), 60ms (typical), and 80ms (maximum), as specified by the "D2" suffix per Table 4 (Reset Timeout Periods). This timeout begins when VCC rises above the 3.705V threshold and MR is deasserted, ensuring the microprocessor completes power stabilization before release. The MAX6855UK38D2+T does not support pin-selectable timeout options.

What type of reset output does the MAX6855UK38D2+T provide?

The MAX6855UK38D2+T provides an active-high push-pull reset output on Pin 1. When asserted (reset active), RESET drives high to ≥0.8×VCC; when deasserted (normal operation), it drives low to ≤0.3V. This eliminates the need for an external pullup resistor and ensures rail-referenced logic compatibility. The MAX6855UK38D2+T differs from MAX6854 (active-low push-pull) and MAX6856 (open-drain) variants in output polarity and drive architecture.

Is the MAX6855UK38D2+T pin-compatible with other SOT23-5 supervisory ICs?

The MAX6855UK38D2+T is pin-compatible with the TPS3836/TPS3837/TPS3838 series per Maxim's documentation, sharing identical 5-pin SOT23-5 layout (Pin 1=RESET, Pin 2=GND, Pin 3=MR, Pin 4=GND, Pin 5=VCC). However, electrical differences exist: TPS383x parts use open-drain outputs and lack internal MR pullup. Direct substitution requires verifying RESET polarity, drive strength, and MR biasing in the target schematic. The MAX6855UK38D2+T is not pin-compatible with MAX686x or MAX6854 variants due to differing pin functions.