Analog Devices Inc./Maxim Integrated MXD1818UR22+T

Overview

MXD1818UR22+T from Maxim Integrated is an open-drain, active-low microprocessor reset supervisor IC designed for +2.5V/+3.0V/+3.3V systems. It monitors VCC and asserts RESET when supply drops below 2.18V (±2.5% accuracy), maintains reset for ≥100ms after VCC recovery, and features debounced manual-reset detection via the RESET pin with 1.5μs minimum low pulse width. Used in portable battery-powered equipment requiring reliable power-on reset and push-button recovery.

For engineers reviewing the MXD1818UR22+T datasheet, MXD1818UR22+T pinout, MXD1818UR22+T application, or MXD1818UR22+T equivalent, key selection criteria include its 2.18V factory-set reset threshold, 4μA quiescent current, -40°C to +105°C operating range, SOT23-3 package, and integrated 5.5kΩ internal pullup resistor enabling direct interface with bidirectional μP reset pins without external components.

Technical Context

The MXD1818UR22+T implements a precision bandgap-based voltage comparator with hysteresis to detect VCC drops below 2.18V and reject fast transients up to 100μs at 200mV overdrive. Its internal timer guarantees ≥100ms reset timeout on both power-up and manual reset release, with debouncing logic filtering mechanical switch bounce before triggering the timeout.

This device uses BiCMOS process technology and integrates an open-drain output stage with internal 5.5kΩ pullup to VCC, supporting sink currents up to 10mA while maintaining valid logic levels down to VCC = +1V - critical for brownout immunity in low-voltage embedded systems.

Key Specifications

Pinout & Package

MXD1818UR22+T is housed in a 3-pin SOT23 package (U3-1 outline) with gull-wing leads, optimized for automated assembly and thermal performance in compact designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1818UR22+T, MAX809TRD3+T offers higher reset voltage but omits manual reset capability, while TPS3808G125DBVR delivers lower power and programmable timing at the cost of added complexity and package size - making MXD1818UR22+T optimal for cost-sensitive, space-constrained +2.5V/+3.3V systems requiring integrated pushbutton support.

Availability

MXD1818UR22+T is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, set-top box power management, and smart sensor node controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MXD1818UR22+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 power-management ICs for industrial, communications, and consumer applications.

The MXD1810–MXD1818 family was engineered to deliver precision, low-power reset supervision for microprocessor-based systems operating at +2.5V, +3.0V, +3.3V, and +5V rails - targeting portable, battery-powered, and thermally demanding embedded platforms.

FAQ

What is the exact reset threshold voltage of MXD1818UR22+T and how accurate is it over temperature?

The MXD1818UR22+T has a factory-set reset threshold of 2.18V with ±2.5% accuracy over the full -40°C to +105°C operating range. This specification is guaranteed by design and verified across temperature extremes, ensuring consistent brownout detection in +2.5V and +3.3V systems without external trimming or calibration. The MXD1818UR22+T maintains this accuracy using a precision bandgap reference and trimmed comparator architecture.

Does MXD1818UR22+T support manual reset, and what are the timing requirements?

Yes, MXD1818UR22+T features debounced manual-reset detection on its RESET pin: a logic-low pulse ≥1.5μs triggers a guaranteed 100ms minimum reset timeout period. This function is specifically implemented in the MXD1813/MXD1818 variants and enables reliable pushbutton recovery without external debounce circuitry. The MXD1818UR22+T releases reset only after the external switch is fully released, not during the press event itself.

What is the output configuration of MXD1818UR22+T and does it require an external pullup resistor?

MXD1818UR22+T has an open-drain, active-low RESET output with an integrated 5.5kΩ pullup resistor to VCC. No external pullup is required - the internal resistor enables direct connection to bidirectional microprocessor reset pins (e.g., Motorola 68HC11) and ensures proper logic-high level when reset is deasserted. This eliminates one passive component and reduces PCB area versus push-pull alternatives.

What is the supply current of MXD1818UR22+T and how does it vary with voltage and temperature?

MXD1818UR22+T draws 4μA typical supply current at +3.6V and room temperature, rising to ≤16μA maximum across the full -40°C to +105°C range and +1.2V to +5.5V VCC. This ultra-low quiescent current is maintained regardless of reset state (asserted or not), making the MXD1818UR22+T ideal for multi-year battery operation in portable and remote sensor applications.

Is MXD1818UR22+T compatible with other packages or pinouts in the MXD181x family?

MXD1818UR22+T uses the standard 3-pin SOT23-3 (U3-1) package and shares identical pinout (VCC–RESET–GND) with all MXD181xUR variants. It is pin-compatible with DS181x-series devices in SOT23, enabling drop-in replacement where 2.18V threshold and manual reset are required. However, SC70-packaged variants (e.g., MXD1818XR22+T) share function but differ mechanically and require layout revision.