Analog Devices Inc./Maxim Integrated MAX6444US26L

Overview

MAX6444US26L from Maxim Integrated is a single-supply microprocessor supervisory circuit with fixed 2.625V reset threshold, active-low open-drain RESET output, and extended manual reset setup period (6.72s). It monitors VCC only, asserts reset during brownout/power-down, and guarantees valid reset down to VCC = 1.0V. Used in set-top boxes and consumer electronics for reliable power-on initialization.

For engineers reviewing the MAX6444US26L datasheet, MAX6444US26L pinout, MAX6444US26L application, or MAX6444US26L equivalent, key selection considerations include its 2.625V fixed threshold, 6.72s manual reset hold time, 6µA supply current, SOT143-4 package, and immunity to <100ns glitches on MR1.

Technical Context

The MAX6444US26L implements a precision bandgap-based voltage monitor with 60ppm/°C tempco and 2×VTH hysteresis. Its internal 50kΩ pullup on MR1 enforces a minimum 6.72s low assertion before generating a one-shot 140ms–280ms RESET pulse.

RESET remains asserted for ≥140ms after VCC recovers above 2.625V or after MR1 is held low ≥6.72s. The open-drain output requires an external pullup and sinks up to 3.2mA at VCC ≥ 4.25V while maintaining VOL ≤ 0.4V.

Key Specifications

Pinout & Package

SOT143-4 package: 1.3mm × 2.9mm footprint, 0.95mm height, gull-wing leads, RoHS-compliant lead-free option available (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6444US26L, MAX6443US26L offers push-pull drive for simpler board layout but forfeits level-shifting capability, while TPS3808G12DBVR reduces supply current by 73% but removes user-controlled reset entirely-making it unsuitable for front-panel recovery workflows.

Availability

MAX6444US26L is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and cable modems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for MAX6444US26L 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 management, sensing, and interface applications.

The MAX6443–MAX6452 family targets cost-sensitive consumer and industrial systems needing robust, low-power reset supervision with configurable manual reset behavior.

FAQ

What is the exact reset threshold voltage of MAX6444US26L?

The MAX6444US26L has a factory-trimmed reset threshold of 2.625V with ±1.5% tolerance over -40°C to +85°C. This value is confirmed in Table 1 of the datasheet, where the "26" suffix corresponds to 2.625V. The device guarantees this threshold stability with 60ppm/°C tempco and includes 2×VTH hysteresis to prevent chatter near the trip point. MAX6444US26L uses this precise threshold to initiate reset when monitored VCC falls below specification.

How does the manual reset function work on MAX6444US26L?

MAX6444US26L features a single active-low manual reset input (MR1) with an extended setup period of 6.72s (denoted by the "L" suffix). MR1 is internally pulled up to VCC via 50kΩ. To assert RESET, MR1 must be held low for ≥6.72s; shorter pulses are ignored. Upon valid assertion, RESET pulses low for ≥140ms. This design prevents accidental resets from brief button presses in consumer interfaces. MAX6444US26L implements this behavior using on-chip timing circuitry with no external components required.

What package type and pin count does MAX6444US26L use?

MAX6444US26L is packaged in a 4-pin SOT143 (also referenced as U4-1) with 1.3mm × 2.9mm footprint and gull-wing leads. Pinout is GND (1), RESET (2), MR1 (3), VCC (4) in top-view orientation. This package supports surface-mount assembly and is qualified for -40°C to +85°C operation. Lead-free versions are available with "+T" suffix. MAX6444US26L's compact SOT143-4 form factor enables high-density PCB layouts in space-constrained consumer devices.

Can MAX6444US26L operate with VCC below 2.625V and still generate a valid reset?

Yes - MAX6444US26L guarantees valid RESET assertion down to VCC = 1.0V, as specified in the Electrical Characteristics table. While the reset threshold remains fixed at 2.625V, the internal comparator and output driver remain functional even as VCC decays from 5.5V to 1.0V. Below 1.0V, RESET behavior is not guaranteed. This feature ensures reliable reset initiation during deep brownout conditions before the µP loses operational margin. MAX6444US26L maintains this guarantee across the full -40°C to +85°C temperature range.

What is the maximum sink current capability of the RESET output on MAX6444US26L?

The open-drain RESET output of MAX6444US26L sinks up to 3.2mA while maintaining VOL ≤ 0.4V when VCC ≥ 4.25V, per the Electrical Characteristics table. At lower VCC levels, sink capability decreases: 100µA at VCC ≥ 1.20V (VOL ≤ 0.3V), 50µA at VCC ≥ 1.00V (VOL ≤ 0.3V). Designers must select an external pullup resistor that ensures sufficient voltage margin for the target µP's reset input threshold under worst-case load. MAX6444US26L's output is rated for 6V absolute maximum, supporting level-shifting to higher-voltage logic rails.