Analog Devices Inc./Maxim Integrated MAX6344MUT+

Overview

MAX6344MUT+ from Maxim Integrated is an active-high push-pull µP supervisory circuit in SOT23-6 packaging, designed to monitor VCC supply voltage and assert a reliable reset signal during power-up, brownout, or low-battery conditions. It features a factory-trimmed 4.38V reset threshold, guaranteed RESET validity down to VCC = +1V, 100ms minimum reset pulse width, and integrated +1.25V power-fail comparator for early-warning monitoring of secondary supplies.

For engineers reviewing the MAX6344MUT+ datasheet, MAX6344MUT+ pinout, MAX6344MUT+ application, or MAX6344MUT+ equivalent, key selection criteria include its active-high push-pull reset output, precise 4.38V threshold tolerance (±25mV over -40°C to +125°C), PFI/PFO monitoring capability, and operation across 1V–5.5V supply range in harsh industrial environments.

Technical Context

The MAX6344MUT+ implements a precision bandgap-based voltage reference and comparator architecture to detect VCC crossing its 4.38V threshold with guaranteed accuracy over temperature. Its internal reset generator enforces a minimum 100ms timeout after VCC rise or MR deassertion, independent of supply slew rate.

Unlike open-drain or active-low variants, the MAX6344MUT+ drives RESET high actively (VOH ≥ 0.8×VCC at ISOURCE = 50µA) and low actively (VOL ≤ 0.4V at ISINK = 1.2mA), eliminating external pull-up components and enabling direct interface with µP reset inputs requiring active-high assertion.

Key Specifications

Pinout & Package

Package: 6-pin SOT23-6, 1.6mm × 2.9mm footprint, surface-mount, lead-free (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar µP supervisory applications.

Compared with MAX6342MUT+, the MAX6344MUT+ provides active-high reset compatibility without external components; versus TLV809M33DBVR, it adds critical PFI/PFO monitoring for multirail systems but requires SOT23-6 layout space.

Availability

MAX6344MUT+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, telecom equipment, multivoltage systems, and embedded control systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6344MUT+ 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, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.

The MAX6342–MAX6345 family delivers highly accurate, temperature-stable µP supervision with integrated power-fail monitoring for systems demanding robust power integrity in harsh environments.

FAQ

What is the exact reset threshold voltage of the MAX6344MUT+ and how tightly is it specified?

The MAX6344MUT+ has a factory-trimmed reset threshold of 4.38V, with a maximum deviation of ±25mV over the full operating temperature range of –40°C to +125°C. This specification is guaranteed by production test, not design simulation, and applies directly to the MAX6344MUT+ variant as confirmed in Maxim's Selector Guide 2 and Electrical Characteristics table. The 4.38V value corresponds to the "M" suffix in the part number and is distinct from other variants like MAX6344LUT+ (4.63V) or MAX6344TUT+ (3.08V).

Does the MAX6344MUT+ support operation down to 1V supply, and what does that mean for system reliability?

Yes, the MAX6344MUT+ is fully specified to operate and assert a valid RESET signal down to VCC = +1.0V, as stated in both Absolute Maximum Ratings and Electrical Characteristics. This means the device continues to monitor supply voltage and maintain correct logic levels on RESET even during severe brownout conditions where many competing supervisors cease functioning or produce indeterminate outputs. For systems powered by aging batteries or unregulated inputs, this ensures deterministic reset behavior throughout the entire discharge curve - a critical feature validated in the MAX6344MUT+ datasheet Figure 2 and Table "VCC Supply Voltage Range".

How does the PFI/PFO function work in the MAX6344MUT+, and what external components are needed?

The MAX6344MUT+ integrates a +1.25V precision reference connected to the inverting input of a comparator. The PFI pin serves as the non-inverting input, so when the voltage at PFI falls below +1.25V, the PFO output goes low. To monitor a secondary supply (e.g., 3.3V), connect a resistor divider between that supply and GND, feeding the midpoint to PFI. No additional active components are required - only two resistors sized per the formula VTH(PFI) = 1.25 × (R1 + R2)/R2. This functionality is explicitly documented for the MAX6344MUT+ in the "Monitoring Two Supplies" section and Figure 7 of the datasheet.

What is the RESET output structure of the MAX6344MUT+, and why does it matter for PCB design?

The MAX6344MUT+ features an active-high push-pull RESET output, meaning it actively drives the pin high (VOH ≥ 0.8×VCC) and low (VOL ≤ 0.4V) without requiring external pull-up resistors. This eliminates one passive component per supervisor, reduces board area, removes potential weak-pull issues, and ensures fast, rail-to-rail transitions compatible with modern µP reset inputs. Unlike the MAX6343MUT+ (open-drain) or MAX6342MUT+ (active-low push-pull), the MAX6344MUT+'s output type is fixed and cannot be reconfigured - a key differentiator confirmed in the Pin Configurations table and Selector Guide 2.

Is the MAX6344MUT+ pin-compatible with other members of the MAX6342–MAX6345 family, and what are the implications for design reuse?

Yes, all MAX6342–MAX6345 variants, including the MAX6344MUT+, share identical 6-pin SOT23-6 pinouts and package dimensions - confirmed in the "Pin Configurations" diagram and "Selector Guide 1". This allows direct PCB footprint reuse across the family. However, functional differences exist: only MAX6342/MAX6344/MAX6345 include MR, while only MAX6344/MAX6345 provide active-high RESET. Therefore, swapping MAX6344MUT+ for MAX6342MUT+ requires verifying µP reset polarity compatibility, but no layout change is needed. This mechanical compatibility is explicitly guaranteed in Maxim's documentation and verified across all ordering variants.