Analog Devices Inc./Maxim Integrated MAX6348UR33+T

Overview

MAX6348UR33+T from Maxim Integrated is an open-drain, active-low microprocessor supervisory circuit designed to monitor 3.3V power supplies and assert a reset signal during brownout, power-up, or power-down events. It features a factory-trimmed 3.30V reset threshold (±1.5% at +25°C), 100ms minimum reset timeout, ultra-low 1µA max supply current, and operates from VCC = 1.2V to 5.5V over -40°C to +85°C. Used in portable battery-powered systems requiring reliable, low-power reset assertion.

For engineers reviewing the MAX6348UR33+T datasheet, MAX6348UR33+T pinout, MAX6348UR33+T application, or MAX6348UR33+T equivalent, key selection criteria include open-drain output compatibility with bidirectional µP reset pins, 3.3V supply monitoring accuracy, 100ms guaranteed reset pulse width, transient immunity against fast VCC glitches, and SOT23-3 footprint constraints for space-constrained designs.

Technical Context

The MAX6348UR33+T implements a precision bandgap-based voltage comparator with hysteresis (9.5mV) to detect VCC falling below its 3.30V threshold. Its internal timing circuit ensures a minimum 100ms reset assertion after VCC recovers above threshold, independent of supply ramp rate.

As an open-drain RESET output device, it requires an external pull-up resistor and supports wired-OR configurations-enabling direct interface with microcontrollers like the Motorola 68HC11 that feature bidirectional reset pins, where either the µP or supervisor can drive the shared reset line low.

Key Specifications

Pinout & Package

MAX6348UR33+T is housed in a 3-pin SOT23-3 package (package code U3-1), with 1.3mm × 2.9mm footprint and 0.95mm height-optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TR33+T and TPS3808G33DBVR, the MAX6348UR33+T uniquely balances ultra-low ICC (1µA), precise 3.30V threshold (±1.5%), and open-drain architecture-making it optimal for battery-critical, multi-source reset bus designs where minimal quiescent power and interoperability are primary constraints.

Availability

MAX6348UR33+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart meter communication subsystems, and automotive BCM sub-circuits requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX6348UR33+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) is a semiconductor company specializing in analog, mixed-signal, and high-reliability ICs for industrial, communications, and consumer applications.

The MAX63xx family was designed specifically for ultra-low-power microprocessor reset supervision in space-constrained, battery-sensitive systems-emphasizing precision threshold accuracy, minimal ICC, and robust transient immunity without external components.

FAQ

What is the exact reset threshold voltage of the MAX6348UR33+T and how tightly is it specified?

The MAX6348UR33+T has a factory-trimmed nominal reset threshold of 3.30V, specified as ±1.5% at +25°C and ±2.5% over the full operating temperature range of –40°C to +85°C. This precision eliminates need for external calibration and ensures reliable 3.3V supply monitoring in production systems. The "R33" suffix in MAX6348UR33+T explicitly denotes this 3.30V threshold variant.

Does the MAX6348UR33+T require an external pull-up resistor on its RESET pin?

Yes, the MAX6348UR33+T features an open-drain RESET output and requires an external pull-up resistor to establish the logic-high level. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements. Without this resistor, the RESET signal cannot reach a valid high state, and the supervised µP will remain held in reset indefinitely.

Can the MAX6348UR33+T operate reliably when the VCC supply drops below 2.0V?

Yes-the MAX6348UR33+T is fully functional down to VCC = 1.2V over the entire –40°C to +85°C temperature range. Its internal comparator and timer continue asserting RESET correctly even during deep brownout, making it suitable for applications where the supply may sag significantly before complete shutdown, such as automotive cranking or battery depletion scenarios.

How does the MAX6348UR33+T handle fast transients on the VCC line?

The MAX6348UR33+T incorporates built-in transient immunity: it ignores negative-going VCC glitches up to 200mV below the 3.30V threshold for durations ≤200µs. This is achieved via internal filtering and comparator hysteresis (9.5mV), preventing false resets caused by switching noise, ESD coupling, or load-step artifacts commonly found in DC-DC converter outputs or shared power rails.

Is the MAX6348UR33+T pin-compatible with older Maxim reset ICs like the MAX809 series?

No-while both MAX6348UR33+T and MAX809TR33+T use the SOT23-3 package and share identical pin numbering (GND/RESET/VCC), their output types differ fundamentally: MAX6348UR33+T is open-drain, whereas MAX809TR33+T is push-pull. Direct substitution requires verifying whether the target µP reset pin tolerates open-drain drive and adding a pull-up resistor if absent. Electrical behavior and system-level timing are not interchangeable without layout review.