Analog Devices Inc./Maxim Integrated MAX6333UR18D3

Overview

MAX6333UR18D3 from Maxim Integrated is a push/pull, active-low microprocessor supervisory circuit in SOT23-3 package, designed for 1.8V power supply monitoring with factory-trimmed 1.80V reset threshold (±1.8% at +25°C), 100ms minimum reset timeout, and guaranteed operation down to 0.7V VCC. It provides reliable power-on/brownout reset for low-voltage embedded controllers and battery-powered instrumentation.

For engineers reviewing the MAX6333UR18D3 datasheet, MAX6333UR18D3 pinout, MAX6333UR18D3 application, or MAX6333UR18D3 equivalent, key selection criteria include its ultra-low 3.3µA supply current at 1.8V, push/pull RESET output compatibility with high-impedance µP reset inputs, immunity to sub-24µs VCC transients, and guaranteed RESET validity down to VCC = 0.7V - critical for fail-safe startup in portable and automotive subsystems.

Technical Context

The MAX6333UR18D3 implements a precision bandgap-based reset comparator with factory-trimmed 1.80V threshold and ±3% tolerance over –40°C to +125°C. Its internal timing circuit generates a fixed 100ms minimum reset pulse width after VCC rises above threshold, independent of external components.

It features a push/pull output stage capable of sourcing ≥200µA at 0.8×VCC and sinking ≥500µA at ≤0.3V, ensuring robust drive into µP reset pins without pull-up resistors. The device ignores fast VCC transients (<24µs at 10V/ms) via comparator hysteresis and propagation delay design.

Key Specifications

Pinout & Package

MAX6333UR18D3 is housed in a 3-pin SOT23-3 package (outline 21-0051), with 1.3mm × 0.8mm footprint and 0.95mm height - suitable for space-constrained PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6333UR18D3, MAX6327UT18D3-T offers identical threshold and timing but demands external pull-up and lacks push/pull drive strength, while TPS3123E18DBVR provides longer timeout and TI qualification but requires board rework - making MAX6333UR18D3 optimal for drop-in 1.8V reset upgrades in space-constrained SOT23-3 layouts.

Availability

MAX6333UR18D3 is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical sensors, automotive body control modules, and IoT edge node gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6333UR18D3 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 high-performance analog, mixed-signal, and power-management ICs for industrial, automotive, and communications markets.

The MAX633x family was designed specifically for ultra-low-voltage microprocessor supervision in battery-powered and space-constrained systems, delivering precision reset functionality without external components.

FAQ

What is the exact reset threshold voltage of MAX6333UR18D3 and how tightly is it specified?

The MAX6333UR18D3 has a factory-trimmed nominal reset threshold of 1.80V, with ±1.8% tolerance at +25°C and ±3% over the full –40°C to +125°C operating range. This precision eliminates the need for external resistor dividers and ensures reliable 1.8V supply monitoring in systems where rail tolerance is tight, such as FPGA I/O banks and low-power microcontrollers. The MAX6333UR18D3 achieves this via laser-trimmed on-chip references.

Does MAX6333UR18D3 require any external components to function?

No, the MAX6333UR18D3 operates as a fully self-contained reset supervisor - no external capacitors, resistors, or diodes are needed. Its internal oscillator and comparator generate the precise 100ms reset timeout and 1.80V threshold without user adjustment. This simplifies layout, reduces BOM cost, and improves reliability compared to discrete reset solutions. The MAX6333UR18D3 is optimized for direct connection between VCC, GND, and the µP RESET pin.

What is the minimum supply voltage at which MAX6333UR18D3 guarantees valid RESET output behavior?

The MAX6333UR18D3 guarantees correct RESET assertion and deassertion down to VCC = 0.7V - meaning it remains functional and outputs valid logic levels even during deep brownout conditions. This is critical for fail-safe operation in battery-powered devices nearing end-of-life. Below 0.7V, behavior is not specified; however, the MAX6333UR18D3 maintains output integrity longer than competing supervisors rated only to 1.0V.

How does MAX6333UR18D3 handle fast voltage transients on the VCC line?

The MAX6333UR18D3 incorporates comparator hysteresis and propagation delay design that rejects negative-going VCC transients shorter than 24µs when slew rate is 10V/ms. This immunity prevents spurious resets caused by switching noise, motor commutation spikes, or digital crosstalk - a key advantage in electrically noisy environments like automotive or industrial settings. The MAX6333UR18D3 achieves this without external RC filters.

Is MAX6333UR18D3 pin-compatible with industry-standard reset ICs?

Yes, the MAX6333UR18D3 uses the standard 3-pin SOT23-3 footprint and pinout (VCC–RESET–GND), making it pin-compatible with MAX809, MAX810, and MAX6326–MAX6328 families. This allows direct replacement in existing designs without PCB modification. The MAX6333UR18D3 retains identical mechanical and electrical interface characteristics while offering improved 1.8V threshold accuracy and lower 3.3µA supply current.