Analog Devices Inc./Maxim Integrated MAX6444US23L+T

Overview

MAX6444US23L+T from Maxim Integrated is a single-supply, fixed-threshold microprocessor reset supervisor IC with one extended-setup manual reset input (MR1), active-low open-drain RESET output, and 2.313V VCC reset threshold. It guarantees valid reset assertion down to VCC = 1.0V, features 6µA typical supply current, and delivers 210ms typical reset timeout after voltage recovery. It is used in consumer electronics power sequencing to prevent code-execution errors during brownout.

For engineers reviewing the MAX6444US23L+T datasheet, MAX6444US23L+T pinout, MAX6444US23L+T application, or MAX6444US23L+T equivalent, key selection criteria include its 2.313V factory-set reset threshold, 6.72s MR1 setup period (L suffix), SOT143-4 package, open-drain output compatibility with 3.3V/5V logic, and immunity to <20µs transients below threshold.

Technical Context

The MAX6444US23L+T monitors only the VCC supply (no RSTIN or MR2) and asserts RESET low when VCC drops below 2.313V ±0.075V. Its internal timing circuitry ensures RESET remains asserted for 210ms (typ) after VCC recovers above threshold - independent of MR1 activity.

Manual reset is implemented via MR1, an active-low input with internal 50kΩ pullup to VCC requiring ≥6.72s low pulse width (tMR, L suffix) to trigger a one-shot 140ms–280ms RESET pulse. Shorter button presses are ignored, eliminating nuisance resets from front-panel switches.

Key Specifications

Pinout & Package

MAX6444US23L+T is housed in a 4-pin SOT143 package (pin pitch 0.95mm, body size 2.9mm × 1.6mm), surface-mount compatible with standard reflow profiles including lead-free (260°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6444US23L+T, MAX6315US23D3+T removes manual reset capability but improves timeout accuracy, while TPS3808G18DBVR adds watchdog functionality at the cost of higher supply current and loss of extended MR1 debounce - making MAX6444US23L+T optimal for cost-sensitive, front-panel-reset-dependent consumer devices.

Availability

MAX6444US23L+T is available at Aetrix Electronics and suitable for set-top boxes, DVD players, and cable/DSL modems requiring stable component supply across industrial temperature ranges and long product lifecycles.

Supply support for MAX6444US23L+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 in industrial, automotive, and consumer markets.

The MAX6443–MAX6452 family delivers robust µP supervision with extended manual reset setup periods, targeting consumer electronics where front-panel switches must serve dual interrupt/reset roles without false triggering.

FAQ

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

The MAX6444US23L+T has a factory-trimmed VCC reset threshold of 2.313V, with guaranteed limits of 2.25V (min) and 2.38V (max) over -40°C to +85°C. This value is encoded in the "23" suffix per Table 1 of the datasheet and applies specifically to the MAX6444US23L+T variant - not the broader MAX6444 family.

How does the MR1 pin on the MAX6444US23L+T behave during normal operation?

The MR1 pin on the MAX6444US23L+T is an active-low manual reset input with an internal 50kΩ pullup to VCC. It remains high during normal operation and only triggers a 140ms–280ms RESET pulse when held low for ≥6.72 seconds (L suffix). Transient low pulses shorter than this are ignored, preventing accidental resets from switch bounce or brief user contact.

Can the MAX6444US23L+T monitor a voltage other than VCC, such as a 1.8V core rail?

No, the MAX6444US23L+T monitors only the VCC supply and lacks an RSTIN pin. It cannot directly supervise secondary rails like 1.8V. For adjustable-threshold monitoring, select MAX6449–MAX6452 variants (e.g., MAX6449UT23L+T), which include RSTIN and support thresholds down to 0.63V via external resistor dividers.

What is the recommended pullup resistor value for the open-drain RESET output of the MAX6444US23L+T?

The datasheet specifies a minimum 20kΩ pullup resistor to VCC for the open-drain RESET output of the MAX6444US23L+T. A 47kΩ resistor is commonly used to balance rise time and current consumption. The pullup must connect to the same voltage domain as the µP's reset input - typically the monitored VCC or a compatible logic rail (0–6V).

Is the MAX6444US23L+T qualified for automotive applications?

No, the MAX6444US23L+T is rated for the extended industrial temperature range (-40°C to +85°C) but is not AEC-Q100 qualified. For automotive use, Maxim offers the MAX6444US16K/V+T variant (1.575V threshold, K suffix, /V grade), explicitly listed as AEC-Q100 qualified in the Ordering Information table.