Analog Devices Inc./Maxim Integrated MAX6866UK37D3L+T

Overview

MAX6866UK37D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.700V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts open-drain active-low RESET during brownout, power-up, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6866UK37D3L+T datasheet, MAX6866UK37D3L+T pinout, MAX6866UK37D3L+T application, or MAX6866UK37D3L+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), watchdog input (WDI) pulse width tolerance of 150ns, and compatibility with 1.2V–5.5V supply range.

Technical Context

The MAX6866UK37D3L+T implements a voltage-monitoring comparator with 2.5% hysteresis, a digital watchdog timer cleared by WDI edges (rising/falling), and a fixed 300ms reset timeout after VCC recovery or MR deassertion. Its internal 10kΩ MR pullup enables direct switch-to-GND interface without external components.

It uses BiCMOS process (2848 transistors) for low leakage and operates across –40°C to +85°C. The open-drain RESET output requires an external pullup and supports logic-level translation up to 5.5V, while WDI accepts CMOS-compatible thresholds (VIH = 0.7×VCC, VIL = 0.3×VCC).

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 MAX6864UK37D3L+T, the MAX6866UK37D3L+T provides flexible open-drain RESET for multi-rail systems, while TPS3838K33DBVR offers lower cost at the expense of missing watchdog and nanopower operation - making MAX6866UK37D3L+T optimal for safety-critical, battery-constrained medical wearables.

Availability

MAX6866UK37D3L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and low-power IoT edge nodes requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6866UK37D3L+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 supervisory functions with integrated watchdog timers, targeting ultra-low-power portable and implantable medical electronics where battery life and functional safety are critical.

FAQ

What is the exact reset threshold voltage of MAX6866UK37D3L+T?

The MAX6866UK37D3L+T has a factory-trimmed reset threshold of 3.700V with ±2.5% tolerance over –40°C to +85°C, as defined by the '37' suffix per Maxim's Threshold Suffix Guide (Table 2). This value is laser-trimmed during production and guaranteed in the Electrical Characteristics table under VTH parameter.

Does MAX6866UK37D3L+T support both manual reset and watchdog functionality?

Yes, MAX6866UK37D3L+T integrates both manual reset (MR pin, active-low, internally pulled up to VCC) and watchdog timer (WDI pin, edge-triggered, 209s typical timeout). Reset asserts if VCC drops below 3.700V, MR is pulled low, or WDI remains static beyond the watchdog period - all covered in the Functional Diagram (Figure 1) and Detailed Description section.

What is the function of Pin 1 (RESET) on MAX6866UK37D3L+T?

Pin 1 of MAX6866UK37D3L+T is the open-drain active-low RESET output. It pulls low during reset conditions (brownout, MR assert, or watchdog timeout) and floats high otherwise. An external pullup resistor is required - typically to the same VCC rail being monitored - to ensure proper logic-high level when deasserted.

Can MAX6866UK37D3L+T operate with supply voltages below 1.8V?

Yes, MAX6866UK37D3L+T operates from 1.2V to 5.5V and guarantees valid reset assertion down to VCC = +1.1V. At 1.2V, its supply current is 190nA (typ), and RESET output can sink ≥50µA - enabling use in emerging sub-1.8V ultra-low-power MCUs and energy-harvesting systems.

How does the watchdog timer in MAX6866UK37D3L+T clear and time out?

The MAX6866UK37D3L+T watchdog timer clears on any rising or falling edge at WDI (Pin 4) and times out if WDI remains static for >209s (typ). It does not count while RESET is asserted. Once RESET deasserts, timing resumes immediately - ensuring robust detection of firmware hangs even during reset recovery sequences.