Analog Devices Inc./Maxim Integrated MAX6855UK33D4+T

Overview

The MAX6855UK33D4+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input (MR), and push-pull active-high RESET output. It asserts reset when VCC drops below its factory-trimmed 3.3V threshold (±2.5%), upon MR assertion, or after reset timeout - with guaranteed reset validity down to VCC = +1.1V and ultra-low 170nA typical supply current. It is used in battery-powered medical devices like glucose monitors to ensure reliable power-on initialization and brownout recovery.

For engineers reviewing the MAX6855UK33D4+T datasheet, MAX6855UK33D4+T pinout, MAX6855UK33D4+T application, or MAX6855UK33D4+T equivalent, key selection considerations include its 3.3V reset threshold, 1200ms minimum reset timeout, active-high push-pull output logic, -40°C to +85°C operating range, and compatibility with low-voltage µP reset inputs requiring clean, glitch-immune assertion.

Technical Context

This device integrates a precision voltage comparator with hysteresis (0.5% of VTH), a monostable reset timeout generator (D4 = 1200ms min), and an internal 10kΩ MR pullup. Its reset assertion is synchronized to VCC falling edge detection with 40µs VCC-to-reset delay and immunity to transients ≤40µs at 100mV overdrive.

The push-pull active-high RESET output delivers VOH ≥ 0.8×VCC (at ISOURCE = 500µA, VCC ≥ 2.38V) and VOL ≤ 0.3V (at ISINK = 1.2mA, VCC ≥ 2.38V), ensuring robust interfacing with 1.8V–5.5V µP reset inputs without external level-shifting.

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 MAX6315US33D3+T, the MAX6855UK33D4+T uniquely combines ultra-low 170nA current, 1200ms timeout, and active-high push-pull output - enabling longer battery life and direct compatibility with modern low-power µPs without external components or logic translation.

Availability

MAX6855UK33D4+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and industrial handheld scanners requiring stable component supply across extended product lifecycles and global manufacturing sites.

Supply support for MAX6855UK33D4+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 in industrial, medical, and communications markets.

The MAX685x family targets ultra-low-power supervisory functions in battery-critical systems, emphasizing nanopower operation, factory-trimmed accuracy, and robust reset timing for reliable µP initialization under brownout conditions.

FAQ

What is the exact reset threshold voltage of the MAX6855UK33D4+T?

The MAX6855UK33D4+T has a factory-trimmed reset threshold of 3.300V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "33" corresponds to VTH = 3.300V (min 3.218V, typ 3.300V, max 3.383V). The MAX6855UK33D4+T maintains this accuracy without external calibration.

Does the MAX6855UK33D4+T include a watchdog timer function?

No, the MAX6855UK33D4+T does not include a watchdog timer. Per the Selector Guide and Pin Descriptions, only MAX6864–MAX6869 variants feature WDI input; the MAX6855UK33D4+T belongs to the MAX6854/MAX6855/MAX6856 group, which provides voltage monitoring and manual reset only. Its part number lacks a watchdog suffix (e.g., "S" or "L"), confirming absence of watchdog functionality.

What is the reset timeout period for the MAX6855UK33D4+T?

MAX6855UK33D4+T has a minimum reset timeout period of 1200ms, indicated by the "D4" suffix per Table 4 (Reset Timeout Periods). Typical and maximum values are 1800ms and 2400ms respectively. This timeout ensures sufficient hold time for complex µP boot sequences, including flash initialization and peripheral configuration, before releasing the active-high RESET signal.

How is the RESET output configured on the MAX6855UK33D4+T?

The MAX6855UK33D4+T features a push-pull active-high RESET output (Pin 1), as confirmed in the MAX6855-specific Pin Description table and Selector Guide. Unlike open-drain variants, it drives high actively without external pullup and sinks current only during deassertion transitions. This configuration directly interfaces with µPs requiring active-high reset assertion, such as many ARM Cortex-M series devices.

Is the MAX6855UK33D4+T compatible with 1.8V microcontrollers?

Yes, the MAX6855UK33D4+T is compatible with 1.8V µCs. Its RESET output delivers VOH ≥ 0.8×VCC (≥1.44V at VCC = 1.8V) with ISOURCE = 200µA, exceeding the VIH requirement of most 1.8V CMOS inputs (typically ≥0.7×VDD = 1.26V). Additionally, its supply range (1.2V–5.5V) and MR input thresholds (0.3×VCC/0.7×VCC) ensure reliable operation across 1.8V system rails.