Analog Devices Inc./Maxim Integrated MAX6855UK33D2+T

Overview

The MAX6855UK33D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing active-high push-pull reset output, manual reset input (MR), and factory-trimmed 3.3V reset threshold with 120ms typical reset timeout. It monitors VCC for brownout detection, asserts reset during power-up/down, and guarantees valid reset operation down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6855UK33D2+T datasheet, MAX6855UK33D2+T pinout, MAX6855UK33D2+T application, or MAX6855UK33D2+T equivalent, key selection criteria include its ultra-low 170nA supply current, immunity to short VCC transients (<40µs at 100mV overdrive), guaranteed reset validity at low supply voltage, and compatibility with CMOS-level MR signaling in space-constrained portable systems.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold tolerance and 0.5% hysteresis, coupled with a digital timeout counter that enforces minimum 40ms reset assertion after VCC recovery and MR deassertion. Its internal 10kΩ MR pullup eliminates external components while supporting momentary switch or open-drain logic interfaces.

The active-high push-pull RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC (at ISOURCE = 200µA) and VOL ≤ 0.3V (at ISINK = 1.2mA), enabling direct interfacing with µP reset inputs without level-shifting. No watchdog timer or CT pin functionality is present - confirming it belongs to the MAX6855 variant group per Selector Guide.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (RoHS-compliant), 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6315US33D2+T, the MAX6855UK33D2+T uniquely combines sub-200nA supply current, active-high push-pull output, and integrated MR pullup - making it optimal for compact, long-life medical and portable electronics where every nanoamp and millisecond matters.

Availability

MAX6855UK33D2+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and MP3 players requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6855UK33D2+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 demanding environments.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and consumer devices - prioritizing nanoscale current draw, small footprint, and robust reset timing.

FAQ

What is the exact reset threshold voltage of the MAX6855UK33D2+T?

The MAX6855UK33D2+T has a factory-trimmed reset threshold of 3.3V with ±2.5% tolerance (3.2175V to 3.3825V). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "33" corresponds to VTH = 3.3V. The MAX6855UK33D2+T uses this precise threshold to reliably detect brownout on standard 3.3V logic rails without external calibration.

Does the MAX6855UK33D2+T include a watchdog timer function?

No, the MAX6855UK33D2+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK33D2+T belongs to the MAX6855 subgroup with MR input and active-high push-pull RESET only. Its functionality is strictly voltage monitoring and manual reset - no watchdog logic or timeout supervision is implemented in the MAX6855UK33D2+T.

What is the reset timeout period for the MAX6855UK33D2+T?

The MAX6855UK33D2+T has a D2 reset timeout option: minimum 40ms, typical 60ms, maximum 80ms. This is defined by the "D2" suffix in the part number and verified in Table 4 (Reset Timeout Periods). The timeout begins after VCC rises above the 3.3V threshold and MR is deasserted, ensuring the microprocessor receives a sufficiently long reset pulse for reliable initialization.

Can the MAX6855UK33D2+T operate with supply voltages below 3.3V?

Yes, the MAX6855UK33D2+T operates from VCC = 1.2V to 5.5V and guarantees valid reset output down to VCC = +1.1V. Its internal voltage reference and comparator remain functional even as VCC falls below the 3.3V threshold - allowing it to assert RESET correctly during deep brownout. This behavior is explicitly specified in the Electrical Characteristics table and validated across -40°C to +85°C.

Is the MAX6855UK33D2+T pin-compatible with other supervisors?

Yes, the MAX6855UK33D2+T is pin-compatible with the TPS3836/TPS3837/TPS3838 family per the Features section, sharing identical 5-pin SOT23-5 pinout (VCC, GND, MR, GND, RESET). However, note that RESET polarity differs: MAX6855UK33D2+T provides active-high push-pull output, whereas TPS3837 offers active-low open-drain - requiring schematic review before substitution.