Analog Devices Inc./Maxim Integrated MAX6856UK19D3+

Overview

The MAX6856UK19D3+ from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 1.9V reset threshold (±2.5%), and 150ms minimum reset timeout period. It monitors VCC, provides manual reset input (MR), and asserts an active-low open-drain RESET output - designed for reliable power-on reset and brownout protection in battery-critical portable medical and consumer devices.

For engineers reviewing the MAX6856UK19D3+ datasheet, MAX6856UK19D3+ pinout, MAX6856UK19D3+ application, or MAX6856UK19D3+ equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), no external components requirement, and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device implements a precision voltage monitor with hysteresis (0.5% of VTH) and a fixed 150ms reset timeout timer. Its MR input features internal 10kΩ pullup, 1µs minimum pulse width support, and 200ns glitch rejection - enabling robust manual reset initiation without external debounce.

The open-drain RESET output operates across full VCC range (1.2V–5.5V), with leakage ≤25nA when deasserted and guaranteed VOL ≤0.3V at ISINK = 1.2mA (VCC ≥2.38V). It requires no external components and remains functional down to VCC = +1.1V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 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 TPS3836K33DBVR and MAX6361KA29D3+, the MAX6856UK19D3+ delivers 10× lower supply current and precise 1.9V threshold - making it uniquely suited for 1.8V rail supervision in energy-constrained medical wearables where every nanoamp matters.

Availability

MAX6856UK19D3+ is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, smart hearing aids, and industrial wireless sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6856UK19D3+ 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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX685x family was engineered specifically for nanopower microprocessor supervision in battery-operated medical and portable electronics - prioritizing ultra-low ICC, wide VCC range, and guaranteed reset validity at sub-1.2V rails.

FAQ

What is the exact reset threshold voltage of the MAX6856UK19D3+?

The MAX6856UK19D3+ has a factory-trimmed reset threshold of 1.900V 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 '19' corresponds to 1.9V nominal. The device guarantees reset assertion when VCC falls below this threshold and remains asserted until VCC exceeds it by hysteresis (0.5% of VTH).

Does the MAX6856UK19D3+ include a watchdog timer function?

No, the MAX6856UK19D3+ does not include a watchdog timer. Per the Selector Guide and Pin Description sections, only MAX6864–MAX6869 variants feature WDI input; the MAX6856 series provides voltage monitoring and manual reset only. The 'UK19D3+' ordering code contains no watchdog suffix (e.g., 'S' or 'L'), confirming its watchdog-disabled configuration.

What is the function of Pin 4 on the MAX6856UK19D3+?

Pin 4 on the MAX6856UK19D3+ is a second GND terminal, electrically connected internally to Pin 2. Its inclusion improves noise immunity and thermal performance in high-density layouts. Unlike variants such as MAX6858/MAX6860, it is not an I.C. (internally connected) pin - and unlike MAX6861–MAX6863, it is not CT. This dual-GND configuration is standard for MAX6854/MAX6855/MAX6856 devices in SOT23-5.

Can the MAX6856UK19D3+ operate with a 1.2V supply?

Yes, the MAX6856UK19D3+ operates across 1.2V to 5.5V, with full functionality including reset assertion and MR input detection. Electrical Characteristics confirm VCC min = 1.2V, and the device guarantees RESET validity down to VCC = +1.1V - enabling reliable supervision of modern ultra-low-voltage MCUs and ASICs powered from 1.2V LDOs.

Is the MAX6856UK19D3+ pin-compatible with other SOT23-5 supervisors?

The MAX6856UK19D3+ shares the same 5-pin SOT23-5 footprint and pinout (RESET/GND/MR/GND/VCC) with MAX6854, MAX6855, and MAX6858 variants. However, it is not pin-compatible with MAX6861–MAX6869 (which replace Pin 4 with CT or WDI) or MAX6858/MAX6860 (which repurpose Pin 1/2 as I.C./GND). Always verify pin function alignment per the specific variant's Pin Description table.