Analog Devices Inc./Maxim Integrated MAX6444US23L+

Overview

MAX6444US23L+ from Maxim Integrated is a single-supply, fixed-threshold microprocessor reset supervisor IC with active-low open-drain RESET output, 2.313V VCC reset threshold, and 6.72s extended manual reset setup period. It monitors VCC only, consumes just 6µA typical supply current, guarantees valid reset down to VCC = 1.0V, and operates across –40°C to +85°C in SOT143 package. It prevents nuisance resets in consumer electronics power sequencing.

For engineers reviewing the MAX6444US23L+ datasheet, MAX6444US23L+ pinout, MAX6444US23L+ application, or MAX6444US23L+ equivalent, key selection considerations include its precise 2.313V reset threshold, 6.72s manual reset hold time, open-drain logic compatibility with 0–6V pull-up voltages, 140ms minimum reset timeout, and immunity to sub-100ns glitches on MR1.

Technical Context

This device implements a precision bandgap-based voltage monitor for VCC with 60ppm/°C tempco and 2×VTH hysteresis. Its internal 50kΩ MR1 pull-up enables direct connection to mechanical switches without external components.

The reset assertion logic combines analog threshold detection with digital timing: VCC drop below 2.313V triggers a one-shot 210ms (typ) reset pulse; MR1 held low ≥6.72s initiates an identical 140ms (min) pulse. Both paths feed into a common open-drain output stage rated for 3.2mA sink at VCC ≥4.25V.

Key Specifications

Pinout & Package

MAX6444US23L+ is housed in a 4-pin SOT143 package (1.3mm × 2.9mm footprint, 1.0mm height), lead-free, RoHS-compliant, and specified for surface-mount reflow up to +260°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6444US23L+, MAX6315US23D+ offers faster manual reset response but sacrifices open-drain interoperability, while TPS3808G18DBVR reduces power consumption by 73% but shifts reset threshold away from the precise 2.313V required for margin-sensitive 2.5V rail supervision.

Availability

MAX6444US23L+ is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and cable modems requiring stable component supply, long-term manufacturability, and guaranteed industrial temperature operation.

Supply support for MAX6444US23L+ 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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications, with emphasis on reliability and integration.

The MAX6443–MAX6452 family was engineered specifically for robust microprocessor supervision in cost-sensitive consumer and industrial equipment, prioritizing glitch immunity, ultra-low current, and mechanical switch compatibility.

FAQ

What is the exact reset threshold voltage of the MAX6444US23L+?

The MAX6444US23L+ has a factory-trimmed VCC reset threshold of 2.313V, with ±1.5% tolerance over –40°C to +85°C. This value is confirmed in Table 1 of the datasheet and corresponds to the "23" suffix in the part number. The threshold exhibits 60ppm/°C tempco and includes 2×VTH hysteresis to prevent chatter near the trip point. MAX6444US23L+ maintains this accuracy without external components.

Does the MAX6444US23L+ support dual-supply monitoring?

No, the MAX6444US23L+ monitors only the VCC supply voltage. It belongs to the MAX6443/MAX6444 subgroup, which are single-fixed-threshold devices with no RSTIN pin. Unlike MAX6449–MAX6452 variants, MAX6444US23L+ lacks adjustable threshold capability and cannot supervise secondary rails. Its sole monitoring channel is dedicated to the VCC pin feeding the IC itself.

What is the function of the MR1 pin on the MAX6444US23L+?

The MR1 pin on the MAX6444US23L+ is an active-low manual reset input with internal 50kΩ pull-up to VCC. To trigger a reset, MR1 must be held low for ≥6.72s (the "L" suffix value). Shorter pulses are ignored, preventing nuisance resets. When asserted, it initiates a 140ms (min) one-shot RESET pulse. MR1 requires no external components and interfaces directly to mechanical switches. MAX6444US23L+ does not support MR2 or immediate-reset functionality.

Can the MAX6444US23L+ operate with VCC below 1.0V?

The MAX6444US23L+ guarantees valid RESET output behavior only down to VCC = 1.0V. Below that, its ability to sink current degrades rapidly, and RESET may float or fail to assert. The datasheet explicitly states "guaranteed valid reset down to VCC = 1.0V" - no operation or specification is provided for VCC < 1.0V. For applications requiring reset validity down to 0V, a pulldown resistor is needed only on push-pull variants; MAX6444US23L+ uses open-drain output and thus relies on its external pull-up.

What package type and dimensions does the MAX6444US23L+ use?

The MAX6444US23L+ is supplied in a 4-pin SOT143 package (package code U4-1), measuring 1.3mm × 2.9mm with 0.95mm pitch and 1.0mm maximum height. It is lead-free and RoHS-compliant, with reflow profile compatible with +260°C peak temperature. Pin 1 is GND, Pin 2 is RESET, Pin 3 is MR1, and Pin 4 is VCC - matching the top-view diagram in the datasheet. No thermal pad or exposed die attach is present.