Analog Devices Inc./Maxim Integrated MXD1818XR26

Overview

MXD1818XR26 from Maxim Integrated is a low-power microprocessor reset supervisor IC designed for +2.5V/+3.0V/+3.3V digital systems. It provides active-low, open-drain RESET output with internal 5.5kΩ pullup resistor, factory-set reset threshold of 2.55V (±2.5% over temperature), 100ms minimum reset timeout, and debounced manual-reset detection requiring ≥1.5μs low pulse on RESET pin. It operates from -40°C to +105°C in SC70-3 package and is used in portable battery-powered equipment to ensure reliable μP initialization during power-up, brownout, and push-button events.

For engineers reviewing the MXD1818XR26 datasheet, MXD1818XR26 pinout, MXD1818XR26 application, or MXD1818XR26 equivalent, key selection considerations include its 2.55V reset threshold accuracy, manual-reset debounce timing, open-drain output compatibility with bidirectional μP reset pins, and guaranteed RESET validity down to VCC = +1V - critical for low-voltage embedded system reliability validation.

Technical Context

The MXD1818XR26 integrates a precision voltage comparator with hysteresis, an internal 100ms reset timeout timer, and dedicated manual-reset debounce logic that detects and filters mechanical switch bounce. Its reset assertion is triggered either by VCC falling below 2.55V or by an externally pulled-low RESET pin held for ≥1.5μs, after which it holds RESET low for ≥100ms post-release.

This device uses BiCMOS process technology and features transient-immune monitoring capable of ignoring VCC glitches up to 100μs (depending on overdrive), while maintaining valid logic states down to VCC = +1V. The open-drain output eliminates need for external pullup resistors and enables wired-OR reset bus configurations with other supervisory devices or μPs.

Key Specifications

Pinout & Package

MXD1818XR26 is housed in a 3-pin SC70 package (outline X3-2, land pattern 90-0208), measuring 2.0mm × 2.1mm × 0.9mm with gull-wing leads. The package is RoHS-compliant and rated for -40°C to +105°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1818XR26, MAX809TRD29+T offers higher threshold but no manual-reset capability, while TPS3808G125DBVR delivers lower ICC but demands external components and layout changes - MXD1818XR26 uniquely combines factory-accurate 2.55V trip point, integrated debounce, and ultra-low 4μA operation in SC70.

Availability

MXD1818XR26 is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, smart energy meters, and wireless sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MXD1818XR26 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 power management ICs for industrial, communications, and consumer applications.

The MXD1810–MXD1818 family was designed specifically for low-power, space-constrained microprocessor reset supervision in battery-operated and thermally demanding environments - emphasizing precision threshold accuracy, minimal external components, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of MXD1818XR26 and how stable is it over temperature?

The MXD1818XR26 has a factory-set reset threshold of 2.55V, with guaranteed accuracy of ±2.5% over the full operating range of -40°C to +105°C. This specification is validated by design and production-tested at +25°C, with limits over temperature ensured by characterization - meaning actual units will maintain trip points between 2.47V and 2.64V across all temperatures, critical for consistent brownout response in 2.5V/3.3V systems.

Does MXD1818XR26 support manual reset, and how does its debounce function work?

Yes, MXD1818XR26 supports manual reset via its RESET pin, which serves as both output and input. When pulled low for ≥1.5μs, it triggers a debounced reset event - rejecting shorter transients caused by mechanical switch bounce. After release, RESET remains low for ≥100ms, ensuring reliable μP initialization. This eliminates need for external RC filters or firmware-based debouncing logic in the host system.

What package type and footprint does MXD1818XR26 use, and is it RoHS-compliant?

MXD1818XR26 uses the 3-pin SC70 package (outline X3-2, land pattern 90-0208), measuring 2.0mm × 2.1mm × 0.9mm. It is RoHS-compliant, with lead-free construction indicated by the "+T" suffix in ordering codes. The SC70 footprint is compatible with standard reflow processes and supports high-density PCB layouts common in portable electronics.

Can MXD1818XR26 operate reliably when VCC drops below 2.0V, and what happens to RESET output?

Yes, MXD1818XR26 guarantees valid RESET logic states down to VCC = +1.0V. As VCC falls below the 2.55V threshold, RESET asserts low and remains asserted until VCC rises above threshold plus hysteresis. Even at VCC = +1.0V, the open-drain output maintains defined behavior - though sinking capability degrades, the internal 5.5kΩ pullup ensures predictable release when VCC recovers.

How does the internal pullup resistor in MXD1818XR26 affect system design compared to external pullup solutions?

The MXD1818XR26 integrates a 5.5kΩ pullup resistor on its open-drain RESET pin, eliminating need for external components and saving board space. This value ensures fast rise time under typical loads (<100pF) while limiting current draw during RESET assertion. Unlike discrete pullups, it's factory-matched and temperature-stable, removing variability in reset timing and improving consistency across production batches.