Analog Devices Inc./Maxim Integrated MAX6445UK29L+

Overview

MAX6445UK29L+ from Maxim Integrated is a dual-manual-reset, fixed-threshold microprocessor supervisor IC with 2.925V VCC reset threshold, 6.72s extended MR1/MR2 setup period, and 140ms minimum reset timeout. It monitors a single supply (VCC) and provides active-low push-pull RESET output for reliable power-on/brownout reset in consumer and industrial embedded systems.

For engineers reviewing the MAX6445UK29L+ datasheet, MAX6445UK29L+ pinout, MAX6445UK29L+ application, or MAX6445UK29L+ equivalent, this page delivers verified electrical parameters, dual manual reset timing behavior, SOT23-5 package mapping, real-world use cases including interrupt-before-reset and smart-card detect, and two validated alternative parts with functional distinctions.

Technical Context

The MAX6445UK29L+ implements a precision bandgap-based voltage monitor with 60ppm/°C tempco and 2×VTH hysteresis, ensuring stable reset assertion across -40°C to +85°C. Its dual extended-setup manual reset inputs (MR1 and MR2) require simultaneous low assertion for ≥6.72s to trigger a one-shot RESET pulse - eliminating nuisance resets from front-panel switch bounce.

RESET asserts when VCC drops below 2.925V (±1.5% over temperature), remains asserted for ≥140ms after VCC recovers above threshold, and guarantees valid logic down to VCC = 1.0V. Internal 50kΩ pullups on MR1 and MR2 eliminate external biasing, and the push-pull output sinks up to 3.2mA at VCC ≥ 4.25V.

Key Specifications

Pinout & Package

MAX6445UK29L+ is housed in a lead-free 5-pin SOT23 package (U5-1 outline), footprint-compatible with industry-standard SOT23-5 land patterns (90-0174). The device measures 2.9mm × 1.6mm × 1.1mm and supports reflow soldering per JEDEC J-STD-020 (260°C peak for Pb-free).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6445UK29L+, MAX6446UK29L+ trades push-pull drive for open-drain flexibility, while MAX6445UK29T+ reduces setup time by 75% - both alter the core reset initiation behavior and require layout or firmware review before substitution.

Availability

MAX6445UK29L+ is available at Aetrix Electronics and suitable for set-top boxes, industrial HMIs, smart card readers, and DVD players requiring stable component supply with guaranteed long-lifecycle support.

Supply support for MAX6445UK29L+ 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 high-reliability industrial and communications systems.

The MAX6443–MAX6452 family was engineered specifically for robust microprocessor supervision in cost-sensitive consumer and industrial equipment, delivering factory-trimmed accuracy, ultra-low power, and noise-immune reset generation in miniature packages.

FAQ

What is the exact reset threshold voltage of MAX6445UK29L+ and how tightly is it specified?

The MAX6445UK29L+ has a factory-set VCC reset threshold of 2.925V, with ±1.5% tolerance over the full -40°C to +85°C operating temperature range. This value is laser-trimmed during production and confirmed in the Electrical Characteristics table (VTH parameter). The 29 suffix in MAX6445UK29L+ directly maps to 2.925V per Table 1 of the datasheet, and the 60ppm/°C tempco ensures minimal drift across temperature.

Does MAX6445UK29L+ support dual manual reset inputs, and what is the required timing relationship between them?

Yes, MAX6445UK29L+ features two dedicated manual reset inputs: MR1 and MR2. Both must be held low simultaneously for the full extended setup period of 6.72 seconds (L suffix) to initiate a one-shot RESET pulse. The device ignores any MR1 or MR2 transitions shorter than this duration, and internal debouncing prevents false triggers from switch bounce - no external RC network is needed.

Can MAX6445UK29L+ generate a valid reset signal when VCC falls below 1.0V?

No - MAX6445UK29L+ guarantees valid RESET output logic only down to VCC = 1.0V. Below this voltage, the internal circuitry cannot maintain defined output states. For applications requiring reset assertion down to 0V, a pulldown resistor (e.g., 100kΩ) must be added to the RESET pin when using the push-pull variant, as described in Figure 9 of the datasheet. This ensures RESET stays low during complete power collapse.

What package type and dimensions does MAX6445UK29L+ use, and is it RoHS-compliant?

MAX6445UK29L+ uses a lead-free 5-pin SOT23 package (package code U5-1, outline 21-0057), measuring 2.9mm × 1.6mm × 1.1mm. The "+" suffix explicitly denotes RoHS-compliant, Pb-free construction per JEDEC J-STD-020 reflow profile (peak 260°C). Land pattern 90-0174 applies, and the device is supplied in tape-and-reel format with 2500-piece minimum order quantity.

How does MAX6445UK29L+ handle short voltage transients on the VCC line?

MAX6445UK29L+ rejects short-duration VCC transients based on overdrive magnitude: for example, a 100mV dip below threshold is ignored if ≤20µs wide (per Maximum Transient Duration vs. Reset Threshold Overdrive graph). This immunity stems from internal filtering and comparator hysteresis (2×VTH), preventing false resets from ESD events, switching regulator noise, or cable-induced glitches - no external capacitor is required.