Analog Devices Inc./Maxim Integrated MAX6866UK26D3S+T

Overview

The MAX6866UK26D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 2.625V reset threshold (suffix '26'), 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 timeout - designed for battery-powered medical and portable electronics requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6866UK26D3S+T datasheet, MAX6866UK26D3S+T pinout, MAX6866UK26D3S+T application, or MAX6866UK26D3S+T equivalent, key selection criteria include its 2.625V threshold accuracy (±2.5%), 150ms–300ms reset timeout range, 3.3s watchdog period, open-drain active-low RESET output, and immunity to sub-40µs VCC transients at 100mV overdrive.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with 250ns MR-to-reset delay and 1µs minimum pulse width, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). Its BiCMOS process enables stable operation from 1.2V to 5.5V supply.

The MAX6866UK26D3S+T implements a fixed-function supervisory architecture: reset assertion occurs on VCC drop below 2.625V, MR low, or WDI timeout; reset remains asserted for ≥150ms after recovery. It guarantees valid RESET output down to VCC = +1.1V and features 20nA WDI input leakage and 10kΩ internal MR pullup.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages. Thermal resistance θ_JA = 140°C/W; max continuous power dissipation = 571mW at +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6866UK26D3S+T, MAX6864UK26D3S+T offers identical supervision specs but different RESET drive architecture, while TPS3836K26DBVR trades nanopower operation and watchdog capability for lower unit cost and simpler implementation in non-safety-critical systems.

Availability

MAX6866UK26D3S+T is available at Aetrix Electronics and suitable for glucose monitoring systems, patient vital sign monitors, industrial handheld scanners, and low-power wireless sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6866UK26D3S+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 communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-constrained medical and portable equipment, emphasizing nanoscale current consumption, precise voltage thresholds, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6866UK26D3S+T?

The MAX6866UK26D3S+T has a factory-trimmed reset threshold of 2.625V, with guaranteed tolerance of ±2.5% over the full -40°C to +85°C operating temperature range. This value is confirmed by the '26' suffix in the part number and specified in Table 2 of the datasheet. The MAX6866UK26D3S+T maintains this accuracy without external calibration.

Does the MAX6866UK26D3S+T support watchdog functionality, and what is its timeout period?

Yes, the MAX6866UK26D3S+T includes a watchdog timer with a typical timeout period of 3.3s, denoted by the 'S' suffix. It monitors the WDI pin and triggers reset if no edge is detected within this period. The MAX6866UK26D3S+T watchdog clears on any rising or falling edge at WDI and resumes counting immediately after reset deassertion.

What type of RESET output does the MAX6866UK26D3S+T provide, and how is it configured?

The MAX6866UK26D3S+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 and wired-OR reset bus implementations. The MAX6866UK26D3S+T does not include internal pullup on RESET; its VOL is ≤0.3V at 50µA sink current.

What is the minimum reset timeout period for the MAX6866UK26D3S+T, and how is it set?

The MAX6866UK26D3S+T has a fixed minimum reset timeout period of 150ms, indicated by the 'D3' suffix. This value is factory-programmed and cannot be adjusted externally. The MAX6866UK26D3S+T guarantees reset assertion for ≥150ms after VCC exceeds 2.625V and MR is deasserted, ensuring reliable µP initialization.

Is the MAX6866UK26D3S+T compatible with 1.8V microcontrollers, and what are the interface considerations?

Yes, the MAX6866UK26D3S+T is fully compatible with 1.8V µPs via its open-drain RESET output: connect the external pullup resistor to the 1.8V supply rail. The MAX6866UK26D3S+T's WDI and MR inputs accept 0.3×VCC to 0.7×VCC logic thresholds, supporting direct connection to 1.8V GPIO. Its 170nA ICC minimizes impact on 1.8V domain power budgets.