Analog Devices Inc./Maxim Integrated MAX6446UK16L

Overview

MAX6446UK16L from Maxim Integrated is a dual-input, fixed-threshold microprocessor supervisory circuit with extended manual reset setup period and active-low open-drain RESET output. It monitors a single supply (VCC) at 1.575V threshold, asserts reset for ≥140ms after VCC or MR inputs drop below threshold or meet extended setup timing, and operates over –40°C to +85°C in 5-pin SOT23 package. Used in set-top boxes and cable modems for reliable power-on and brownout protection.

For engineers reviewing the MAX6446UK16L datasheet, MAX6446UK16L pinout, MAX6446UK16L application, or MAX6446UK16L equivalent, key selection concerns include its 1.575V VCC reset threshold, 6.72s dual-MR extended setup period, open-drain RESET logic, guaranteed operation down to VCC = 1.0V, and immunity to <20µs transients at 100mV overdrive.

Technical Context

The MAX6446UK16L implements dual active-low manual reset inputs (MR1 and MR2), both requiring simultaneous low assertion for ≥6.72s (tMR = L suffix) to trigger a one-shot RESET pulse. Its internal comparator monitors VCC against a factory-trimmed 1.575V threshold with 60ppm/°C tempco and 2×VTH hysteresis.

RESET remains asserted for 140ms minimum (210ms typical) after VCC recovers above threshold or after valid MR assertion. The open-drain output requires an external pullup resistor (≥20kΩ to VCC) and sinks up to 3.2mA at VCC ≥ 4.25V while consuming only 6µA typical supply current.

Key Specifications

Pinout & Package

MAX6446UK16L is housed in a 5-pin SOT23 package (package code U5+1, outline 21-0057), with exposed pad not electrically connected. Pin 1 is GND, pin 2 is VCC, pin 3 is MR1, pin 4 is RESET, and pin 5 is MR2 - all pins support voltages from –0.3V to +6V.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6446UK16L, MAX6445UK16L reduces reset input flexibility by omitting MR2, while TPS3808G16DBVR trades extended setup immunity for lower quiescent current and shorter timeout - neither offers the same dual-MR + 6.72s debounce combination.

Availability

MAX6446UK16L is available at Aetrix Electronics and suitable for set-top boxes, cable modems, DVD players, and industrial control panels requiring stable component supply across extended temperature ranges and long-term production cycles.

Supply support for MAX6446UK16L 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 timing, targeting consumer electronics and industrial equipment where accidental resets must be eliminated.

FAQ

What is the exact reset threshold voltage for MAX6446UK16L?

The MAX6446UK16L has a factory-trimmed VCC reset threshold of 1.575V, with a guaranteed range of 1.52V to 1.62V at +25°C. This value is specified in Table 1 of the datasheet under suffix "16", and applies directly to the MAX6446UK16L. The threshold exhibits 60ppm/°C temperature coefficient and includes 2×VTH hysteresis to prevent chatter near trip point.

How does the dual manual reset function work on MAX6446UK16L?

The MAX6446UK16L requires both MR1 and MR2 inputs to be held low simultaneously for the full 6.72s extended setup period (tMR = L suffix) before asserting RESET. Neither input alone triggers reset - this dual-input requirement prevents accidental resets from single-button presses. Internal 50kΩ pullups keep both inputs high by default, and the device ignores transitions shorter than tMR.

Is MAX6446UK16L compatible with 3.3V or 5V systems?

Yes, MAX6446UK16L operates from 1.0V to 5.5V and monitors only its own VCC pin - it does not require matching between monitored rail and logic levels. Its open-drain RESET output can be pulled up to any voltage from 0V to 6V, enabling direct interface with 3.3V or 5V µP reset inputs regardless of VCC supply voltage.

What is the minimum required pullup resistor for the open-drain RESET output of MAX6446UK16L?

The MAX6446UK16L datasheet specifies a minimum 20kΩ pullup resistor to VCC for the open-drain RESET output. This ensures proper logic-high level under worst-case sink conditions (e.g., 3.2mA at VCC ≥ 4.25V). Larger values (e.g., 100kΩ) are acceptable if rise time requirements permit, but values below 20kΩ may cause excessive power dissipation or violate VOL spec.

Does MAX6446UK16L provide reset assertion during power-up sequencing?

Yes, MAX6446UK16L asserts RESET low during power-up until VCC rises above 1.575V and remains above that threshold for the entire reset timeout period (≥140ms). This guarantees the connected µP remains held in reset until the supply is fully stabilized, preventing premature code execution - a critical function explicitly supported by the device's design and guaranteed across –40°C to +85°C.