Analog Devices Inc./Maxim Integrated MAX6855UK39D5+T

Overview

The MAX6855UK39D5+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and fixed reset timeout (300ms min) with factory-trimmed 3.9V reset threshold. It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout - ensuring reliable µP initialization in ultra-low-power systems. Used in glucose monitors and portable medical devices where supply stability and battery life are critical.

For engineers reviewing the MAX6855UK39D5+T datasheet, MAX6855UK39D5+T pinout, MAX6855UK39D5+T application, or MAX6855UK39D5+T equivalent, this page delivers verified electrical specs, pin-level design meaning, real-world use scenarios, and validated alternative options for low-voltage, long-battery-life embedded supervision.

Technical Context

The MAX6855UK39D5+T implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C and guarantees valid RESET down to VCC = 1.1V. Its internal timer enforces a minimum 300ms reset pulse after VCC recovery or MR release, with 250ns MR-to-reset delay and 1µs minimum MR pulse width.

This variant belongs to the MAX6854–MAX6869 family with active-high push-pull RESET output, no watchdog timer (WDI pin absent), and no CT pin - distinguishing it from MAX6864–MAX6869 (watchdog-enabled) and MAX6861–MAX6863 (pin-selectable timeout). It uses BiCMOS process and integrates 2848 transistors.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (2.9mm × 1.6mm × 1.1mm), lead-free, RoHS-compliant, rated for -40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6369KA29D3+T, the MAX6855UK39D5+T offers the lowest quiescent current (170nA), factory-trimmed 3.9V threshold for 3.3V systems with margin, and active-high push-pull output - making it optimal for space-constrained, battery-critical medical wearables.

Availability

MAX6855UK39D5+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, portable diagnostic tools, and smart inhalers requiring stable component supply across extended production lifecycles.

Supply support for MAX6855UK39D5+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 industrial, medical, and communications applications.

The MAX6854–MAX6869 product line delivers nanopower supervisory circuits optimized for battery longevity and reliability in portable healthcare and IoT edge devices - emphasizing ultra-low ICC, wide VCC range, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of the MAX6855UK39D5+T?

The MAX6855UK39D5+T has a factory-trimmed reset threshold of 3.900V (minimum 3.802V, maximum 3.998V) with ±2.5% tolerance over temperature. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "39" corresponds to 3.9V nominal. The MAX6855UK39D5+T uses this precise threshold to supervise 3.3V systems with sufficient headroom against ripple and drift.

Does the MAX6855UK39D5+T include a watchdog timer function?

No, the MAX6855UK39D5+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 capability is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UKxxDxxS+T), identifiable by the "S" or "L" suffix in the ordering code. The MAX6855UK39D5+T pinout lacks WDI, confirming absence of watchdog circuitry.

What is the reset timeout period for the MAX6855UK39D5+T, and how is it set?

The MAX6855UK39D5+T has a fixed minimum reset timeout period of 300ms, indicated by the "D5" suffix in its part number. This value is specified in Table 4 (Reset Timeout Periods) as D5 = 300ms (min), 450ms (typ), 600ms (max). Unlike MAX6861–MAX6863, the MAX6855UK39D5+T does not feature a CT pin or programmable timeout - the 300ms duration is factory-configured and non-adjustable.

What type of RESET output does the MAX6855UK39D5+T provide, and how does it interface to a microcontroller?

The MAX6855UK39D5+T provides an active-high push-pull RESET output (Pin 1), meaning it drives high during reset assertion and low during deassertion. It interfaces directly to µP reset inputs requiring active-high logic without external pullup resistors. VOH is guaranteed ≥0.8×VCC at ISOURCE = 500µA, and VOL ≤0.3V at ISINK = 1.2mA - compatible with standard 3.3V and 1.8V logic families.

Is the MAX6855UK39D5+T pin-compatible with other supervisory ICs, and what package does it use?

Yes, the MAX6855UK39D5+T uses a standard 5-pin SOT23-5 package (2.9mm × 1.6mm) and is pin-compatible with TPS3836/TPS3837/TPS3838 series supervisory ICs, as noted in the datasheet Features section. Pin mapping matches: Pin 1 = RESET, Pins 2 & 4 = GND, Pin 3 = MR, Pin 5 = VCC. This allows direct replacement in existing layouts where active-high RESET and 3.9V threshold meet system requirements.