Analog Devices Inc./Maxim Integrated MAX6855UK40D3+T

Overview

The MAX6855UK40D3+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 4.000V reset threshold with 150ms minimum reset timeout. It monitors VCC supply integrity, asserts reset during brownout or manual trigger, and guarantees valid reset operation down to VCC = +1.1V. It is used in battery-powered medical devices such as glucose monitors to ensure reliable µP initialization under low-voltage conditions.

For engineers reviewing the MAX6855UK40D3+T datasheet, MAX6855UK40D3+T pinout, MAX6855UK40D3+T application, or MAX6855UK40D3+T equivalent, key selection criteria include its 4.000V reset threshold tolerance (±2.5%), 170nA typical supply current at 2.5V, 150ms reset timeout option (D3), and compatibility with CMOS-level MR inputs and push-pull RESET logic interfacing.

Technical Context

The MAX6855UK40D3+T implements a voltage-monitoring comparator with hysteresis (0.5% of VTH) and an internal reset timer that holds RESET high for ≥150ms after VCC exceeds 4.000V and MR deasserts. Its MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection - enabling robust manual reset in noisy portable environments.

This variant belongs to the MAX6854–MAX6869 family but excludes watchdog timer (WDI) and CT timeout-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 1.8V–5.5V µP reset inputs.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (+T suffix), footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3837K33DBVR and MAX6316LUK40D3+T, the MAX6855UK40D3+T uniquely combines 4.000V threshold, active-high push-pull RESET, and integrated MR in a nanopower SOT23 - simplifying design for medical-grade 4.0V rail supervision without external components.

Availability

MAX6855UK40D3+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and handheld medical diagnostics requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6855UK40D3+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 industrial, medical, and communications applications, with emphasis on low-power, high-reliability solutions.

The MAX6854–MAX6869 product line delivers nanopower supervisory circuits optimized for battery-critical portable medical and consumer electronics, combining voltage monitoring, manual reset, and watchdog functions in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6855UK40D3+T?

The MAX6855UK40D3+T has a factory-trimmed reset threshold of 4.000V, with guaranteed tolerance of ±2.5% over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "40" corresponds to 4.000V nominal. The MAX6855UK40D3+T maintains this accuracy without external calibration or trimming components.

Does the MAX6855UK40D3+T include a watchdog timer function?

No, the MAX6855UK40D3+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 timer capability is exclusive to MAX6864–MAX6869 variants, as confirmed in the Selector Guide and Pin Description sections of the datasheet.

What is the reset timeout period for the MAX6855UK40D3+T, and how is it selected?

The MAX6855UK40D3+T has a fixed 150ms minimum reset timeout period, indicated by the "D3" suffix in its part number. This value is one of six factory-configured options (D1–D6) and cannot be adjusted externally. The datasheet specifies D3 as 150ms (min), 225ms (typ), and 300ms (max) - ensuring sufficient hold time for µP power stabilization and peripheral initialization.

What type of reset output does the MAX6855UK40D3+T provide, and how does it interface with a microcontroller?

The MAX6855UK40D3+T provides a push-pull active-high RESET output (Pin 1). When asserted, RESET goes high (VOH ≥ 0.8×VCC); when deasserted, it goes low (VOL ≤ 0.3V). This eliminates the need for external pullup resistors and directly interfaces with µPs requiring active-high reset inputs, such as many ARM Cortex-M series devices. The output is fully specified from VCC = 1.2V to 5.5V.

Is the MR (manual reset) input of the MAX6855UK40D3+T internally pulled up, and what is its logic threshold?

Yes, the MR input of the MAX6855UK40D3+T is internally pulled up to VCC through a 10kΩ resistor, as documented in the Pin Description table. Its logic thresholds are VIH ≥ 0.7×VCC and VIL ≤ 0.3×VCC, supporting standard CMOS-level signals. A momentary switch from MR to GND suffices for manual reset; no external components are required, and the input rejects glitches shorter than 200ns.