Analog Devices Inc./Maxim Integrated MAX6444US46L+T

Overview

MAX6444US46L+T from Maxim Integrated is a single-supply, fixed-threshold microprocessor reset supervisor IC with active-low open-drain RESET output, 4.625V VCC reset threshold (±130mV), 6.72s extended manual reset setup period (tMR), and guaranteed operation down to VCC = 1.0V. It monitors only the VCC supply, features low 6µA quiescent current, and is used in consumer electronics like DVD players and cable modems to prevent code-execution errors during power-up, brownout, or accidental button presses.

For engineers reviewing the MAX6444US46L+T datasheet, MAX6444US46L+T pinout, MAX6444US46L+T application, or MAX6444US46L+T equivalent, key selection considerations include its SOT143-4 package, 4.625V precision reset threshold, immunity to <20µs transients at 100mV overdrive, pushbutton-compatible long-setup MR1 input, and open-drain RESET logic requiring external pullup.

Technical Context

The MAX6444US46L+T implements a precision bandgap-based voltage monitor for VCC only, with factory-trimmed 4.625V reset threshold (±130mV) and 60ppm/°C tempco. Its internal timing circuit enforces a fixed 6.72s low assertion on MR1 before generating a 210ms (typ) one-shot RESET pulse - eliminating nuisance resets from brief switch closures.

RESET asserts low when VCC falls below 4.625V and remains asserted for ≥140ms after VCC recovers above threshold. The open-drain output supports level-shifting up to 6V and sinks ≥50µA at VCC ≥1.0V, with VOL ≤0.3V. No RSTIN or dual-monitor capability is present - this is a single-voltage, single-MR1 device.

Key Specifications

Pinout & Package

MAX6444US46L+T uses a 4-pin SOT143 package with exposed pad (not electrically connected). Pin 1 = GND, Pin 2 = VCC, Pin 3 = MR1, Pin 4 = RESET. All pins support −0.3V to +6V absolute max ratings; MR1 has internal 50kΩ pullup to VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6444US46L+T, the K-suffix variant increases reset assurance at the cost of user responsiveness, while the TPS3808G33DBVR trades extended MR capability for lower current and smaller footprint - neither offers identical 6.72s setup + 4.625V precision in SOT143.

Availability

MAX6444US46L+T is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and cable modems requiring stable component supply, long-term industrial temperature support (-40°C to +85°C), and RoHS-compliant lead(Pb)-free packaging.

Supply support for MAX6444US46L+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 power, sensing, and interface applications, with emphasis on reliability and integration for demanding environments.

The MAX6443–MAX6452 family delivers robust µP supervision with extended manual reset timing, targeting consumer, industrial, and automotive systems where accidental resets must be eliminated without sacrificing brownout protection.

FAQ

What is the exact reset threshold voltage of the MAX6444US46L+T and how tightly is it specified?

The MAX6444US46L+T has a factory-set VCC reset threshold of 4.625V, with a guaranteed tolerance of ±130mV (4.50V to 4.75V) across −40°C to +85°C. This precision is achieved via laser trimming during production and is documented in the Electrical Characteristics table under "VCC Reset Threshold" with suffix "46". The MAX6444US46L+T does not require external resistors or calibration to achieve this accuracy.

How does the 6.72s manual reset setup period (tMR) function in the MAX6444US46L+T?

The MAX6444US46L+T requires MR1 to remain continuously low for exactly 6.72 seconds (L-suffix) before asserting RESET - a feature designed to reject brief switch closures. Once asserted, RESET stays low for 210ms (typical). The internal timer debounces MR1 transitions, so no external RC filter is needed. This behavior is confirmed in the "Manual Reset Input Options" section and Table 2 of the MAX6444US46L+T datasheet.

Can the MAX6444US46L+T monitor voltages other than VCC, such as a 1.8V core rail?

No, the MAX6444US46L+T monitors only the VCC supply pin and does not include an RSTIN input. It is part of the MAX6443/MAX6444 subgroup, which lacks adjustable-threshold capability. For monitoring secondary rails like 1.8V, consider the MAX6449–MAX6452 series (e.g., MAX6449UT29L+T), which add RSTIN with 0.63V reference. The MAX6444US46L+T is strictly a single-rail, fixed-threshold supervisor.

What package type and pin count does the MAX6444US46L+T use, and is it RoHS compliant?

The MAX6444US46L+T uses a 4-pin SOT143 package (outline 21-0052), measuring 1.3mm × 1.3mm, with GND, VCC, MR1, and RESET pins in standard top-view orientation. It is supplied in lead(Pb)-free packaging ("+T" suffix), fully RoHS compliant, and rated for operation from −40°C to +85°C. This package is distinct from the 5-pin SOT23 used by MAX6445–MAX6448 and 6-pin SOT23 used by MAX6449–MAX6452.

Does the MAX6444US46L+T provide push-pull or open-drain RESET output, and what pullup is required?

The MAX6444US46L+T provides an active-low open-drain RESET output (as indicated by "US46L+T" ordering code and confirmed in the Pin Configurations table). An external pullup resistor to VCC (minimum 20kΩ) is mandatory for proper logic-level translation. The device does not support push-pull output - that variant is designated "US46L/V+T" or similar with different suffixes. The MAX6444US46L+T's open-drain architecture enables level-shifting to higher-voltage logic domains up to 6V.