Analog Devices Inc./Maxim Integrated MAX6855UK39D1+T

Overview

The MAX6855UK39D1+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring active-high push-pull reset output, manual reset input (MR), and factory-trimmed 3.9V reset threshold (±2.5%). It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), with 10ms minimum reset timeout and guaranteed reset validity down to VCC = +1.1V. It targets ultra-low-power portable systems such as glucose monitors and battery-powered PDAs.

For engineers reviewing the MAX6855UK39D1+T datasheet, MAX6855UK39D1+T pinout, MAX6855UK39D1+T application, or MAX6855UK39D1+T equivalent, this page delivers verified functional identity, exact pin roles, confirmed reset timing behavior, true supply current at 170nA (typ), and validated alternative options for voltage-monitoring and reset-generation use cases.

Technical Context

The MAX6855UK39D1+T implements a precision bandgap-based voltage monitor with 2.5% threshold tolerance and hysteresis of 0.5% VTH, ensuring immunity to short VCC transients (e.g., ≤40µs at 100mV overdrive). Its internal 10kΩ MR pullup enables direct CMOS-level manual reset control without external components.

Unlike watchdog-equipped variants (MAX6864–MAX6869), the MAX6855UK39D1+T omits WDI functionality and CT input - it belongs to the core supervisory subset (MAX6854/MAX6855/MAX6856) with fixed reset timeout and no programmable delay selection. Its push-pull active-high RESET output is referenced to VCC and sinks ≤0.3V at 1.2mA load.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint, 1.1mm max height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6855UK39D1+T, the TPS3836K33DBVR demands external biasing and draws ~10× more current, while the MAX6326UR29+T provides incompatible reset polarity and inadequate timeout duration for brownout recovery - making MAX6855UK39D1+T uniquely suited for 3.9V-rail, active-high, ultra-low-I_CC applications.

Availability

MAX6855UK39D1+T is available at Aetrix Electronics and suitable for glucose monitors, portable medical sensors, and industrial handheld terminals requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK39D1+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, with emphasis on reliability and low-power innovation.

The MAX6854–MAX6869 family delivers nanopower supervisory functions for battery-critical systems, targeting portable medical, industrial, and consumer equipment where extended runtime and robust reset behavior are essential.

FAQ

What is the exact reset threshold voltage of the MAX6855UK39D1+T?

The MAX6855UK39D1+T has a factory-trimmed reset threshold of 3.900V, with ±2.5% tolerance across temperature (–40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "39" corresponds to 3.900V nominal. The MAX6855UK39D1+T maintains this specification without external calibration or trimming.

Does the MAX6855UK39D1+T include a watchdog timer function?

No, the MAX6855UK39D1+T does not include a watchdog timer. It belongs to the MAX6854/MAX6855/MAX6856 subgroup, which provides only voltage monitoring and manual reset. Watchdog functionality is exclusive to MAX6864–MAX6869 variants (e.g., MAX6864UK39D1S+T), identifiable by the "S" or "L" suffix in the ordering code.

What is the reset output configuration of the MAX6855UK39D1+T?

The MAX6855UK39D1+T features an active-high push-pull RESET output (Pin 1), meaning it drives high during reset assertion and low otherwise. This eliminates the need for an external pullup resistor and ensures fast, low-impedance transitions - unlike open-drain or active-low variants in the same family.

Can the MAX6855UK39D1+T operate reliably below 1.8V supply voltage?

Yes, the MAX6855UK39D1+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. At 1.2V, its supply current remains ultra-low (~190nA typ), and reset assertion timing (tRD = 40µs) is fully characterized - making it suitable for sub-1.8V energy-harvesting or low-voltage backup rails.

Is the MAX6855UK39D1+T pin-compatible with other supervisory ICs?

Yes, the MAX6855UK39D1+T uses a standard 5-pin SOT23-5 package with identical pinout to TPS3836/TPS3837/TPS3838 devices (as noted in the datasheet Features section). Pin 1 = RESET, Pins 2&4 = GND, Pin 3 = MR, Pin 5 = VCC - enabling direct replacement in existing layouts where active-high push-pull reset is supported.