Analog Devices Inc./Maxim Integrated MAX6445UK31L+T

Overview

The MAX6445UK31L+T from Maxim Integrated is a dual manual reset, fixed-threshold microprocessor supervisor IC with 3.075V VCC reset threshold, 6.72s extended MR1/MR2 setup period, push-pull active-low RESET output, and guaranteed operation from -40°C to +85°C. It monitors a single supply (VCC) and asserts reset during brownout or power-up, supporting set-top boxes, DVD players, and industrial equipment where nuisance resets must be avoided.

For engineers reviewing the MAX6445UK31L+T datasheet, MAX6445UK31L+T pinout, MAX6445UK31L+T application, or MAX6445UK31L+T equivalent, key selection criteria include its dual extended-setup manual reset inputs, 3.075V precision reset threshold, 6.72s tMR timing, SOT23-5 package, and immunity to short switch closures - critical for front-panel reset reliability in consumer and industrial systems.

Technical Context

The MAX6445UK31L+T implements a dual-input manual reset architecture requiring simultaneous assertion of MR1 and MR2 for ≥6.72s to trigger a one-shot 140ms–280ms RESET pulse. Its internal 50kΩ pullup on both MR1 and MR2 enables direct connection to mechanical switches without external components.

It features a precision 3.075V ±0.075V factory-set VCC reset threshold with 60ppm/°C tempco and guarantees valid RESET down to VCC = 1.0V. The push-pull RESET output drives low to ≤0.3V at 1.2mA sink current and deasserts to ≥0.8×VCC, eliminating need for external pullup resistors.

Key Specifications

Pinout & Package

MAX6445UK31L+T is housed in a 5-pin SOT23 package (package code U5+1), with 1.3mm × 2.9mm footprint and 0.95mm height, optimized for space-constrained consumer and industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK31L+T, the MAX6445UK31T+T offers faster reset activation but reduced nuisance immunity, while the TPS3808G33DBVR provides basic supervision at lower complexity but cannot implement coordinated dual-button reset sequences essential for secure field recovery.

Availability

MAX6445UK31L+T is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and industrial HMIs requiring stable component supply, long-life design assurance, and guaranteed extended-temperature operation.

Supply support for MAX6445UK31L+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 and mixed-signal ICs for industrial, communications, and consumer applications.

The MAX6443–MAX6452 family delivers robust µP supervision with extended manual reset setup periods, targeting front-panel-reliant consumer electronics and industrial control systems where accidental resets must be eliminated.

FAQ

What is the exact reset threshold voltage of the MAX6445UK31L+T?

The MAX6445UK31L+T has a factory-trimmed VCC reset threshold of 3.075V, with a guaranteed range of 3.00V to 3.15V over temperature (-40°C to +85°C). This value is specified in Table 1 of the datasheet and corresponds directly to the "31" suffix in the part number. The threshold exhibits 60ppm/°C tempco, ensuring stability across the full operating range. The MAX6445UK31L+T does not support adjustable thresholds - RSTIN is not present on this variant.

How does the dual manual reset function work on the MAX6445UK31L+T?

The MAX6445UK31L+T requires both MR1 and MR2 inputs to be held low simultaneously for the full 6.72s extended setup period (denoted by the "L" suffix) before asserting the RESET output. Neither input alone triggers reset; both must meet the timing condition. This dual-input coordination prevents accidental resets from single-button presses. After assertion, RESET remains low for 140ms minimum, then deasserts. The MAX6445UK31L+T includes internal 50kΩ pullups on both MR1 and MR2, enabling direct switch-to-ground connection without external resistors.

What package type and pin count does the MAX6445UK31L+T use?

The MAX6445UK31L+T uses a 5-pin SOT23 package (outline 21-0057, land pattern 90-0174), designated as U5+1 in Maxim's packaging nomenclature. Pin 1 is GND, Pin 2 is VCC, Pin 3 is MR1, Pin 4 is MR2, and Pin 5 is RESET. This compact 1.3mm × 2.9mm footprint supports high-density layouts in space-constrained consumer electronics. The "UK" prefix in the part number explicitly denotes the SOT23-5 package variant.

Does the MAX6445UK31L+T support open-drain or push-pull RESET output?

MAX6445UK31L+T features a push-pull active-low RESET output, as confirmed by the "U" in the ordering code (per Pin Configuration table) and functional diagram. It drives low to ≤0.3V at 1.2mA sink current and high to ≥0.8×VCC when deasserted, eliminating the need for an external pullup resistor. This differs from open-drain variants like MAX6446UK31L+T, which require a pullup to VCC or another rail. The push-pull configuration ensures defined logic levels across the full 1.0V–5.5V VCC range.

What is the minimum VCC voltage at which the MAX6445UK31L+T guarantees valid RESET operation?

The MAX6445UK31L+T guarantees valid RESET output logic down to VCC = 1.0V, as stated in the Electrical Characteristics table and General Description. Below 1.0V, reset functionality is not assured - the IC may fail to assert or maintain RESET correctly. This specification enables reliable operation during deep brownout conditions common in battery-powered or unregulated supply systems. For applications requiring reset validity down to 0V, an external pulldown resistor is required only on push-pull variants, but MAX6445UK31L+T does not require it above 1.0V.