Analog Devices Inc./Maxim Integrated MAX6446UK26L

Overview

The MAX6446UK26L from Maxim Integrated is a dual manual reset, fixed-threshold microprocessor supervisor IC with active-low open-drain RESET output, 4.625V VCC reset threshold, and 6.72s extended MR1/MR2 setup period. It monitors a single supply (VCC), asserts reset during brownout or power-down, and provides 210ms typical timeout after recovery. Used in set-top boxes and cable modems for reliable system initialization and front-panel reset immunity.

For engineers reviewing the MAX6446UK26L datasheet, MAX6446UK26L pinout, MAX6446UK26L application, or MAX6446UK26L equivalent, key selection criteria include its dual extended manual reset architecture, guaranteed reset validity down to VCC = 1.0V, low 6µA supply current, SOT23-5 package, and immunity to <100ns glitches on MR inputs.

Technical Context

The MAX6446UK26L implements a precision voltage monitor with factory-trimmed 4.625V reset threshold (±1.5% over -40°C to +85°C) and 60ppm/°C tempco. Its dual manual reset inputs (MR1 and MR2) require simultaneous low assertion for ≥6.72s to trigger a one-shot 140ms–280ms RESET pulse - preventing nuisance resets from brief switch closures.

It features internal 50kΩ pullups on both MR1 and MR2, open-drain RESET with 1µA leakage when deasserted and 0.4V VOL at 3.2mA sink, and operates across 1.0V–5.5V VCC. The device is fully specified over the extended industrial temperature range (-40°C to +85°C) and uses BiCMOS process technology.

Key Specifications

Pinout & Package

MAX6446UK26L is housed in a 5-pin SOT23 package (package code U5+1, outline 21-0057), with 0.95mm pitch, 2.9mm × 1.6mm footprint, and exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK26L, the MAX6446UK26L adds a second manual reset input for enhanced fault tolerance; compared with TPS3808G33DBVR, it trades lower ICC for superior glitch immunity and deliberate dual-input reset control - critical in consumer UI environments.

Availability

MAX6446UK26L is available at Aetrix Electronics and suitable for set-top boxes, cable modems, DVD players, and industrial media gateways requiring stable component supply, long-term lifecycle support, and guaranteed performance across -40°C to +85°C.

Supply support for MAX6446UK26L 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, communications, and consumer applications.

The MAX6443–MAX6452 family was designed specifically for robust microprocessor supervision in noise-prone consumer electronics, featuring extended manual reset timing and precision voltage monitoring to eliminate false resets.

FAQ

What is the exact reset threshold voltage of the MAX6446UK26L?

The MAX6446UK26L has a factory-trimmed VCC reset threshold of 4.625V, with guaranteed tolerance of ±1.5% over the full -40°C to +85°C operating range. This value is confirmed in Table 1 of the datasheet under suffix "26", and is optimized for reliable detection of brownout on nominal 5V supplies before microprocessor malfunction occurs. The MAX6446UK26L maintains this accuracy with 60ppm/°C tempco.

Does the MAX6446UK26L support dual manual reset functionality?

Yes, the MAX6446UK26L supports true dual manual reset: both MR1 and MR2 inputs must be held low simultaneously for the full 6.72s extended setup period (suffix "L") to assert the RESET output. This architecture prevents accidental resets and is explicitly documented in the Pin Description and Manual Reset Input Options sections of the datasheet. The MAX6446UK26L does not support independent or immediate reset via either input.

What package type and pin count does the MAX6446UK26L use?

The MAX6446UK26L is packaged in a 5-pin SOT23 (package code U5+1, outline 21-0057), with pinout: 1=GND, 2=VCC, 3=MR1, 4=MR2, 5=RESET. This compact 2.9mm × 1.6mm surface-mount package is RoHS-compliant and optimized for high-density consumer PCB layouts. The MAX6446UK26L shares footprint compatibility with other SOT23-5 supervisors but is not pin-compatible with SOT143 or SOT23-6 variants in the same family.

Can the MAX6446UK26L operate with VCC below 1.0V?

No - the MAX6446UK26L is guaranteed to provide valid RESET output only for VCC ≥ 1.0V, as stated in the Absolute Maximum Ratings and Electrical Characteristics tables. Below 1.0V, RESET output behavior is unspecified and may become indeterminate. For applications requiring reset assertion down to 0V, an external pulldown resistor is incompatible with the MAX6446UK26L's open-drain output; a push-pull variant like MAX6445US26L would be required instead.

What is the minimum pullup resistor value required for the MAX6446UK26L RESET output?

The MAX6446UK26L RESET output requires a minimum 20kΩ external pullup resistor to VCC or another logic rail, as specified in the Pin Description section. This value ensures proper VOL (≤0.4V at 3.2mA sink) and avoids excessive current draw during RESET assertion. Using a smaller resistor increases power consumption and may exceed the 3.2mA sink capability, while larger values risk slow rise times in noisy environments. The MAX6446UK26L datasheet confirms this requirement applies to all open-drain variants in the family.