Analog Devices Inc./Maxim Integrated MAX6855UK20D2+T

Overview

MAX6855UK20D2+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, providing active-high push-pull reset output, manual reset input (MR), and factory-trimmed 2.0V reset threshold with 10ms minimum reset timeout. It monitors VCC supply voltage down to +1.1V, asserts reset during power-up/brownout, and consumes only 170nA typical supply current. Used in battery-powered glucose monitors and portable medical devices requiring ultra-low-power supervision.

For engineers reviewing the MAX6855UK20D2+T datasheet, MAX6855UK20D2+T pinout, MAX6855UK20D2+T application, or MAX6855UK20D2+T equivalent, key selection criteria include its 2.0V reset threshold tolerance (±2.5%), guaranteed reset validity at VCC = +1.1V, immunity to sub-40µs VCC transients, and compatibility with CMOS-level MR input and push-pull RESET output referenced to VCC.

Technical Context

The MAX6855UK20D2+T implements a precision bandgap-based voltage monitor with 2.5% hysteresis and internal 10kΩ MR pullup. Its reset assertion logic combines VCC falling-edge detection, MR low-level assertion, and fixed 10ms timeout timer - no watchdog or CT pin functionality is present, distinguishing it from MAX6861–MAX6869 or MAX6864–MAX6869 variants.

Unlike open-drain or active-low versions, this part drives RESET high upon fault condition and holds it high for ≥10ms after VCC exceeds 2.0V and MR deasserts. The push-pull output ensures defined logic levels without external components, and the device remains functional across –40°C to +85°C with guaranteed operation down to VCC = +1.1V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, 2.9mm × 1.6mm × 1.1mm, lead-free (RoHS-compliant) with +T suffix.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K20DBVR and MAX6315US20D2+T, the MAX6855UK20D2+T uniquely delivers active-high push-pull RESET with nanopower consumption and 10ms timing - enabling direct interface to modern low-voltage MCUs without level translation or additional passive components.

Availability

MAX6855UK20D2+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial handheld terminals requiring stable component supply with long-term lifecycle support.

Supply support for MAX6855UK20D2+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 communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in space- and energy-constrained portable systems, emphasizing nanoscale current draw, wide VCC range, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of the MAX6855UK20D2+T?

The MAX6855UK20D2+T has a factory-trimmed reset threshold of 2.000V with ±2.5% tolerance over –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) where "20" corresponds to 2.000V nominal, and Electrical Characteristics specify VTH = VTH ±2.5% under all operating conditions. The device asserts RESET when VCC falls below this threshold and holds it until VCC rises above the threshold plus hysteresis (0.5% of VTH).

Does the MAX6855UK20D2+T include a watchdog timer function?

No, the MAX6855UK20D2+T does not include a watchdog timer. Per the Selector Guide and Pin Description, only MAX6864–MAX6869 variants feature WDI input; MAX6855 belongs to the MAX6854/MAX6855/MAX6856 group which provides voltage monitoring and manual reset only. The absence of WDI pin (Pin 4 is GND) and lack of watchdog-related parameters in its Electrical Characteristics confirm this.

What is the function of Pin 4 on the MAX6855UK20D2+T?

Pin 4 on the MAX6855UK20D2+T is GND - a second ground connection shared with Pin 2. As shown in the "MAX6854/MAX6855/MAX6856 Pin Description" table and Top View diagram, both Pins 2 and 4 are labeled GND. This dual-ground configuration improves thermal performance and reduces ground impedance in high-noise portable applications, and must be connected to the same system ground potential.

Can the MAX6855UK20D2+T drive a reset input that requires active-low signaling?

The MAX6855UK20D2+T provides an active-high push-pull RESET output (Pin 1), so it cannot directly drive an active-low reset input without external inversion. To interface with such MCUs, use a single NPN transistor or logic inverter; however, note that adding components increases quiescent current and board area. For native active-low compatibility, consider MAX6854UK20D2+T (active-low push-pull) or MAX6856UK20D2+T (open-drain active-low).

What is the maximum VCC transient duration the MAX6855UK20D2+T can ignore at 100mV overdrive?

At 100mV reset threshold overdrive (i.e., VCC transient dipping 100mV below the 2.0V threshold), the MAX6855UK20D2+T is immune to transients ≤40µs in duration, as specified in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph (Figure MAX684 toc05). This immunity prevents false resets caused by switching noise or load-step events in battery-powered systems.