Analog Devices Inc./Maxim Integrated MAX6444US46L+

Overview

MAX6444US46L+ from Maxim Integrated is a single-supply, fixed-threshold microprocessor supervisory circuit with one extended-setup manual reset input (MR1), active-low open-drain RESET output, and 4.625V VCC reset threshold. It guarantees valid reset assertion down to VCC = 1.0V, consumes only 6µA typical supply current, and provides 210ms typical reset timeout - designed for reliable power-up/brownout monitoring in consumer and industrial embedded systems.

For engineers reviewing the MAX6444US46L+ datasheet, MAX6444US46L+ pinout, MAX6444US46L+ application, or MAX6444US46L+ equivalent, key selection considerations include its SOT143-4 package, 6.72s manual reset setup period (L suffix), open-drain logic compatibility with 0–6V pullup voltages, and immunity to <20µs transients at 100mV overdrive - critical for front-panel pushbutton-driven reset integrity.

Technical Context

The MAX6444US46L+ integrates a precision voltage comparator monitoring VCC against a factory-trimmed 4.625V threshold (±1.5% tolerance), with 60ppm/°C tempco and 2×VTH hysteresis. Its MR1 input features internal 50kΩ pullup and requires ≥6.72s low assertion before generating a one-shot RESET pulse.

RESET asserts low for ≥140ms (min) and 210ms (typ) after VCC recovery or MR1 activation, with guaranteed operation across -40°C to +85°C. The open-drain output sinks up to 3.2mA at VCC ≥ 4.25V while maintaining VOL ≤ 0.4V, enabling direct interface to µP reset inputs powered by independent supplies.

Key Specifications

Pinout & Package

MAX6444US46L+ is housed in a lead-free 4-pin SOT143 package (U4-1 outline), measuring 2.9mm × 1.5mm × 1.1mm, with gull-wing leads optimized for automated assembly and thermal performance in space-constrained designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6443US46L+, the MAX6444US46L+ offers open-drain flexibility for mixed-voltage reset buses but requires an external pullup; versus TPS3808G33DBVR, it delivers superior front-panel robustness via 6.72s debounce but targets higher-voltage rails and consumes slightly more current.

Availability

MAX6444US46L+ is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and cable modems requiring stable component supply with guaranteed long-term manufacturability and RoHS-compliant packaging.

Supply support for MAX6444US46L+ 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 to solve nuisance reset issues in front-panel-controlled electronics, combining precision voltage monitoring with programmable long-duration manual reset inputs for robust system-level supervision.

FAQ

What is the exact reset threshold voltage of the MAX6444US46L+?

The MAX6444US46L+ has a factory-trimmed VCC reset threshold of 4.625V, with ±1.5% tolerance over temperature and supply variations. This value is confirmed in Table 1 of the datasheet and corresponds to the "46" suffix in the part number. The MAX6444US46L+ uses this precise threshold to monitor 4.6V nominal rails without external components, ensuring accurate brownout detection in systems like cable modems and DVD players.

Does the MAX6444US46L+ support operation below 1.8V supply?

Yes, the MAX6444US46L+ is fully specified to operate down to VCC = 1.0V, with guaranteed RESET output validity throughout that range. Its internal circuitry remains functional and asserts RESET correctly even during deep brownout conditions. This capability is critical for battery-powered devices where supply voltage may sag below 1.8V before shutdown - a feature explicitly validated in the Electrical Characteristics table under "Guaranteed Valid Reset Down to VCC = 1.0V".

How does the 6.72s manual reset setup period prevent nuisance resets in the MAX6444US46L+?

The MAX6444US46L+ requires MR1 to remain low for a minimum of 6.72 seconds (L suffix) before asserting RESET - a duration far exceeding typical mechanical switch bounce or accidental presses. This extended setup period is implemented via internal timing circuitry that debounces transitions without external components. As documented in the Manual Reset Input Options section, this design ensures only intentional, sustained user action triggers system reset - essential for consumer electronics like set-top boxes where front-panel buttons serve dual UI and reset functions.

Can the MAX6444US46L+ be used with a 1.8V microprocessor reset input?

Yes, the MAX6444US46L+ supports interfacing with 1.8V µP reset inputs via its open-drain RESET output. By connecting the external pullup resistor to a 1.8V rail (not VCC), the RESET signal swings between 0V and 1.8V, meeting the logic thresholds of 1.8V CMOS inputs. The datasheet confirms RESET can interface to voltages from 0V to 6V, and Figure 8 explicitly illustrates this level-shifting configuration - making the MAX6444US46L+ compatible with mixed-voltage systems without additional logic buffers.

What is the maximum transient duration the MAX6444US46L+ can ignore at 100mV overdrive?

At a reset threshold overdrive of 100mV (i.e., VCC falling 100mV below the 4.625V threshold), the MAX6444US46L+ ignores transients lasting ≤20µs, as shown in the "Maximum Transient Duration vs. Reset Threshold Overdrive" graph (toc03). This immunity is achieved through internal filtering and comparator hysteresis, preventing false resets from EMI-induced supply noise or switching regulator ripple. The specification is tested and guaranteed across the full -40°C to +85°C temperature range, ensuring reliability in electrically noisy environments like industrial HMI controllers.