Analog Devices Inc./Maxim Integrated MAX6866UK46D3S+T

Overview

The MAX6866UK46D3S+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 4.625V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR) assertion, and triggers reset on watchdog expiration - designed for battery-critical applications like glucose monitors and portable medical devices.

For engineers reviewing the MAX6866UK46D3S+T datasheet, MAX6866UK46D3S+T pinout, MAX6866UK46D3S+T application, or MAX6866UK46D3S+T equivalent, this page delivers verified electrical specs, SOT23-5 terminal mapping, real-world use cases in low-power embedded systems, and two validated alternative parts with documented functional and timing differences.

Technical Context

The MAX6866UK46D3S+T implements a voltage-monitoring comparator with hysteresis (0.5% of VTH), a precision reset timeout generator (D3 = 150–300ms), and a watchdog timer that clears on any WDI edge and expires after 3.3s (typ) if inactive. Its internal 10kΩ MR pullup and guaranteed RESET validity down to VCC = +1.1V enable robust brownout recovery without external components.

This device belongs to the MAX6864–MAX6869 series with active-low open-drain RESET output, requiring an external pullup resistor. Unlike push-pull variants, its open-drain configuration supports level-shifting across logic domains (0–5.5V) and eliminates shoot-through risk during power sequencing.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with JEDEC MO-178AB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK46D3S+T, the MAX6866UK46D3S+T's open-drain output enables flexible reset bus architecture and logic-level translation, while TPS3838K33DBVR trades nanopower operation and watchdog safety for broader temperature qualification - making MAX6866UK46D3S+T optimal for long-life, safety-critical portable medical devices.

Availability

MAX6866UK46D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6866UK46D3S+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 MAX6864–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-constrained medical and portable electronics, integrating voltage monitoring, manual reset, and watchdog functions into a single 5-pin SOT23 package.

FAQ

What is the exact reset threshold voltage of the MAX6866UK46D3S+T?

The MAX6866UK46D3S+T has a factory-trimmed reset threshold voltage of +4.625V, with a guaranteed tolerance of ±2.5% over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the official datasheet, where suffix "46" explicitly corresponds to 4.625V nominal. The MAX6866UK46D3S+T maintains this accuracy without external calibration.

Does the MAX6866UK46D3S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6866UK46D3S+T includes a watchdog timer with a typical timeout of 3.3 seconds, indicated by the "S" suffix in the part number. As specified in Table 3 (Watchdog Timeout), the S-suffix guarantees a minimum of 1.5s and maximum of 7.75s. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period - a core safety feature of the MAX6866UK46D3S+T.

What type of reset output does the MAX6866UK46D3S+T provide, and how is it used?

The MAX6866UK46D3S+T provides an active-low open-drain RESET output (Pin 1). This requires an external pullup resistor to the target logic supply (e.g., 1.8V or 3.3V), enabling level-shifting and wired-OR reset bus configurations. Unlike push-pull variants, this output cannot source current - it only sinks current when asserted - making the MAX6866UK46D3S+T ideal for interfacing with mixed-voltage systems without additional level translators.

What is the minimum supply voltage at which the MAX6866UK46D3S+T guarantees valid reset assertion?

The MAX6866UK46D3S+T guarantees valid reset assertion down to VCC = +1.1V, as stated in the Electrical Characteristics table under "Guaranteed Reset Valid to VCC = +1.1V". This specification ensures deterministic behavior during deep brownout conditions - critical for medical devices where reliable reset must occur even as primary batteries discharge below 1.2V. This guarantee applies specifically to the MAX6866UK46D3S+T and is not extrapolated from other family members.

How does the manual reset (MR) input function on the MAX6866UK46D3S+T?

The MR input (Pin 3) on the MAX6866UK46D3S+T is an active-low signal with an internal 10kΩ pullup to VCC. Driving MR low asserts RESET for the full timeout period (300ms typ), and RESET remains asserted for that duration even after MR returns high. MR accepts standard CMOS logic levels and is immune to glitches shorter than 200ns. When unused, MR may be left floating or tied to VCC - no external components are required, simplifying design around the MAX6866UK46D3S+T.