Analog Devices Inc./Maxim Integrated MAX6866UK29D3S-T

Overview

The MAX6866UK29D3S-T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold (suffix "29"), 150ms minimum reset timeout (suffix "D3"), and watchdog timer with 3.3s typical timeout (suffix "S"). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - used in battery-powered medical and portable electronics where long-term reliability and low quiescent power are critical.

For engineers reviewing the MAX6866UK29D3S-T datasheet, MAX6866UK29D3S-T pinout, MAX6866UK29D3S-T application, or MAX6866UK29D3S-T equivalent, key selection criteria include its 2.925V ±2.5% reset threshold, open-drain active-low RESET output, -40°C to +85°C operation, and compatibility with systems requiring guaranteed reset validity down to VCC = +1.1V.

Technical Context

The MAX6866UK29D3S-T implements a voltage-monitoring comparator with hysteresis (0.5% of VTH), a monostable reset timeout generator (150ms min), and an independent watchdog timer that clears on any WDI edge and expires after 3.3s (typ) of inactivity. Its internal MR pullup (10kΩ) and glitch rejection (200ns) support robust manual reset handling without external components.

It uses BiCMOS process technology (2848 transistors) and operates across 1.2V–5.5V VCC, with reset assertion guaranteed down to VCC = +1.1V and immunity to VCC transients ≤40µs at 100mV overdrive - enabling stable supervision in noisy, low-voltage battery systems.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, RoHS-compliant), 2.9mm × 1.6mm × 1.1mm profile, thermal pad optional.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK29D3S-T, the MAX6866UK29D3S-T's open-drain output enables shared reset busing and voltage-level translation, while its 170nA ICC provides >10× longer battery life versus TPS3838K29DBVR - critical for maintenance-free medical and wearable deployments.

Availability

MAX6866UK29D3S-T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and wearable health trackers requiring stable component supply across extended product lifecycles.

Supply support for MAX6866UK29D3S-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, mixed-signal, and power-management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervision with integrated watchdog and manual reset for battery-critical systems - engineered specifically for multi-year operation in glucose monitors, wearables, and remote sensors.

FAQ

What is the exact reset threshold voltage of the MAX6866UK29D3S-T?

The MAX6866UK29D3S-T has a factory-trimmed reset threshold of 2.925V, 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 "29" corresponds to 2.925V (min 2.852V, typ 2.925V, max 2.998V). The MAX6866UK29D3S-T guarantees valid reset assertion down to VCC = +1.1V, making it suitable for deep brownout detection in low-voltage systems.

Does the MAX6866UK29D3S-T include a watchdog timer, and what is its timeout?

Yes, the MAX6866UK29D3S-T includes a watchdog timer with a typical timeout of 3.3s, indicated by the "S" suffix in the part number. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period. The MAX6866UK29D3S-T datasheet specifies min/typ/max values of 1.5s/3.3s/7.75s, and the timeout is temperature-stable per the normalized tWD vs. temperature curve (Figure MAX6854 toc04).

What type of reset output does the MAX6866UK29D3S-T provide, and how is it configured?

The MAX6866UK29D3S-T provides an open-drain active-low RESET output (Pin 1), requiring an external pullup resistor to the target logic voltage. This configuration enables level-shifting, wired-OR reset busing, and interfacing with µPs powered by different supply rails. The MAX6866UK29D3S-T datasheet confirms this in the Pin Description table and Selector Guide, distinguishing it from push-pull variants like MAX6864UK29D3S-T.

What is the minimum reset timeout period for the MAX6866UK29D3S-T, and how is it set?

The MAX6866UK29D3S-T has a fixed minimum reset timeout period of 150ms, denoted by the "D3" suffix. This value is factory-programmed and cannot be altered externally. The datasheet's Table 4 lists D3 as 150ms (min), 225ms (typ), and 300ms (max), and the timing is guaranteed across temperature and voltage. Unlike MAX6861–MAX6863, the MAX6866UK29D3S-T does not feature a CT pin for dynamic timeout selection.

Is the MAX6866UK29D3S-T compatible with 1.8V or 2.5V supply systems?

Yes, the MAX6866UK29D3S-T operates from 1.2V to 5.5V VCC and is fully specified across this range, including at 1.8V and 2.5V. Its 170nA supply current is measured at VCC = 1.8V, and RESET output performance (VOL ≤0.3V at ISINK = 50µA) is guaranteed down to VCC = +1.1V. The MAX6866UK29D3S-T's voltage monitor accuracy and watchdog timing remain valid across the entire supply range, supporting mixed-voltage embedded designs.