Analog Devices Inc./Maxim Integrated MAX6855UK20D5+T

Overview

The MAX6855UK20D5+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 2.0V reset threshold. It asserts reset during VCC brownout, MR assertion, or watchdog timeout (not applicable to MAX6855), with guaranteed reset validity down to VCC = +1.1V and ultra-low 170nA typical supply current. It is used in battery-powered medical monitors and portable electronics requiring reliable power-on reset and low-quiescent-current supervision.

For engineers reviewing the MAX6855UK20D5+T datasheet, MAX6855UK20D5+T pinout, MAX6855UK20D5+T application, or MAX6855UK20D5+T equivalent, key selection criteria include its 2.0V reset threshold tolerance (±2.5%), 450ms minimum reset timeout (D5 option), active-high push-pull RESET logic, -40°C to +85°C operating range, and compatibility with 1.2V–5.5V supply rails.

Technical Context

The MAX6855UK20D5+T implements a precision voltage monitor with hysteresis (0.5% of VTH) and an internal reset timeout generator. Its MR input features 10kΩ internal pullup, 1µs minimum pulse width, and 200ns glitch rejection - enabling robust manual reset initiation without external components.

This variant belongs to the MAX6854–MAX6869 family but excludes watchdog timer (WDI) and CT select functionality. It delivers push-pull active-high RESET output referenced to VCC, with VOH ≥ 0.8×VCC (at ISOURCE = 500µA) and VOL ≤ 0.3V (at ISINK = 1.2mA), ensuring clean interface with modern µP reset inputs.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Pin 1 is RESET (active-high push-pull), Pin 2 and Pin 4 are GND, Pin 3 is MR (active-low manual reset), Pin 5 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K20DBVR and MAX6315US20D3+T, the MAX6855UK20D5+T uniquely combines nanopower consumption (170nA), active-high push-pull output, and 450ms timeout - making it optimal for next-generation battery-powered medical and portable devices where reset timing and energy efficiency are co-critical.

Availability

MAX6855UK20D5+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and MP3 players requiring stable component supply across extended production lifecycles and temperature ranges.

Supply support for MAX6855UK20D5+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 consumer applications.

The MAX6854–MAX6869 product line was designed specifically for ultra-low-power microprocessor supervision in battery-constrained portable equipment, emphasizing sub-µA quiescent current, wide supply range, and integrated reset timing without external components.

FAQ

What is the exact reset threshold voltage of the MAX6855UK20D5+T?

The MAX6855UK20D5+T has a factory-trimmed reset threshold of 2.000V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "20" corresponds to 2.000V nominal. The device guarantees valid reset operation down to VCC = +1.1V, making it suitable for brownout detection in low-voltage systems.

Does the MAX6855UK20D5+T include a watchdog timer function?

No, the MAX6855UK20D5+T does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input and watchdog timeout functionality. The MAX6855UK20D5+T is a dedicated voltage supervisor with manual reset (MR) and fixed reset timeout - confirmed by absence of WDI pin and omission from watchdog-related electrical characteristics tables.

What does the "D5" in MAX6855UK20D5+T indicate?

The "D5" suffix in MAX6855UK20D5+T specifies the reset timeout period option: 450ms minimum (with typical 600ms and maximum 1200ms values per Table 4). This timeout begins after VCC rises above the 2.0V threshold and MR is deasserted, ensuring sufficient hold time for µP initialization. The D5 option is selected at manufacture and cannot be changed in-circuit.

Is the MAX6855UK20D5+T pin-compatible with other MAX68xx supervisory ICs?

The MAX6855UK20D5+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, GND, VCC) with MAX6854, MAX6856, MAX6861–MAX6863, and MAX6864–MAX6869. However, pin compatibility does not imply functional equivalence: MAX6855 provides active-high push-pull RESET, while MAX6854 offers active-low push-pull and MAX6856 offers active-low open-drain - requiring schematic review before substitution.

What is the supply current specification for the MAX6855UK20D5+T at 1.8V?

At VCC = 1.8V and TA = +25°C, the MAX6855UK20D5+T draws 170nA typical supply current (ICC) when reset is deasserted and no load is applied - verified in the Electrical Characteristics table under "Supply Current" with condition "VCC = 1.8V". This ultra-low ICC enables multi-year operation on primary lithium cells and is a defining feature of the MAX6854–MAX6869 nanopower family.