Analog Devices Inc./Maxim Integrated MAX6864UK31D3L+

Overview

The MAX6864UK31D3L+ from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, integrating voltage monitoring (3.075V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. It targets ultra-low-power portable medical and consumer devices requiring reliable power-on reset and firmware fault recovery.

For engineers reviewing the MAX6864UK31D3L+ datasheet, MAX6864UK31D3L+ pinout, MAX6864UK31D3L+ application, or MAX6864UK31D3L+ equivalent, key selection criteria include its 170nA typical supply current, 3.075V ±2.5% reset threshold, 300ms minimum reset timeout, 209s watchdog period, and compatibility with battery-powered systems operating down to 1.2V.

Technical Context

The MAX6864UK31D3L+ implements a dual-trigger reset architecture: one path monitors VCC against a precision bandgap-based threshold (3.075V), while a second path detects absence of transitions on the WDI pin beyond 209s. Its internal timer ensures RESET remains asserted for ≥300ms after VCC recovery, MR release, or watchdog expiration.

It features a 10kΩ internal MR pullup, 150ns minimum WDI pulse width detection, and immunity to VCC transients ≤40µs at 100mV overdrive. The push-pull RESET output sinks ≥1.2mA at VCC ≥2.38V and sources ≥500µA at VCC ≥2.38V, eliminating external pullup requirements.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK31D3L+, MAX6865UK31D3L+ offers identical supervision performance but inverted RESET polarity, while TPS3836K33DBVR provides basic voltage monitoring at higher current and without watchdog capability-making MAX6864UK31D3L+ the sole choice for ultra-low-power, watchdog-critical designs.

Availability

MAX6864UK31D3L+ is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and smart pagers requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX6864UK31D3L+ 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 and mixed-signal ICs for power, sensing, and interface applications in industrial, medical, and consumer markets.

The MAX6864UK31D3L+ belongs to the nanopower µP supervisory family, engineered specifically for battery-critical portable electronics needing simultaneous voltage monitoring, manual reset, and long-period watchdog functionality in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6864UK31D3L+?

The MAX6864UK31D3L+ has a factory-trimmed reset threshold voltage of 3.075V, with ±2.5% tolerance over the -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "31" corresponds to 3.075V. The MAX6864UK31D3L+ uses this precise threshold to reliably supervise 3.3V system rails during power-up, brownout, and shutdown conditions.

Does the MAX6864UK31D3L+ require external components for basic operation?

No, the MAX6864UK31D3L+ requires no external components for core functionality. It integrates a 10kΩ internal pullup on the MR pin, precision timing for both reset and watchdog functions, and a push-pull active-low RESET output that drives µP reset inputs directly. Only a 0.1µF ceramic bypass capacitor from VCC to GND is recommended for noise immunity - no resistors, capacitors, or additional ICs are needed for voltage monitoring, manual reset, or watchdog operation in the MAX6864UK31D3L+.

What is the watchdog timeout period of the MAX6864UK31D3L+ and how is it configured?

The MAX6864UK31D3L+ features a watchdog timeout period of 209s (typical), denoted by the "L" suffix in its part number. This long timeout is factory-configured and fixed - no external pins or registers adjust it. The watchdog timer resets on any rising or falling edge at the WDI pin and triggers a reset if WDI remains static (high or low) beyond 209s. This behavior is fully specified in Table 3 (Watchdog Timeout) and applies identically across all operating temperatures for the MAX6864UK31D3L+.

Can the MAX6864UK31D3L+ operate reliably at very low supply voltages?

Yes, the MAX6864UK31D3L+ guarantees valid reset assertion down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table. Its internal circuitry remains functional and the RESET output maintains defined logic states even as VCC drops below typical µP operating ranges. This ensures deterministic system behavior during deep battery discharge - a critical requirement for medical and portable devices where the MAX6864UK31D3L+ is deployed.

What package type and pin configuration does the MAX6864UK31D3L+ use?

The MAX6864UK31D3L+ is supplied in a 5-pin SOT23-5 surface-mount package with standardized pinout: Pin 1 = RESET (active-low push-pull), Pin 2 = GND, Pin 3 = MR (active-low manual reset), Pin 4 = WDI (watchdog input), Pin 5 = VCC. This configuration is confirmed in the "MAX6864/MAX6865/MAX6866 Pin Description" section and the "Pin Configurations" diagram on page 15 of the datasheet, and is consistent across all MAX6864 variants.