Analog Devices Inc./Maxim Integrated MXD1818UR23+T

Overview

MXD1818UR23+T from Maxim Integrated is an open-drain, active-low microprocessor reset IC with debounced manual-reset capability, factory-set 2.31V reset threshold, 100ms minimum reset timeout, and operation down to VCC = +1V. It monitors +2.5V/+3.0V/+3.3V power supplies in portable and industrial embedded systems, asserting RESET when VCC falls below threshold or when RESET pin is held low ≥1.5μs.

For engineers reviewing the MXD1818UR23+T datasheet, MXD1818UR23+T pinout, MXD1818UR23+T application, or MXD1818UR23+T equivalent, key selection criteria include its 2.31V threshold accuracy (±2.5%), internal 5.5kΩ pullup resistor, 4μA supply current at +3.6V, -40°C to +105°C temperature range, and SOT23-3 package compatibility with manual-reset–enabled μP supervisory designs.

Technical Context

The MXD1818UR23+T implements a precision bandgap-based voltage comparator with hysteresis and an internal timer for fixed 100ms reset assertion after VCC recovery. Its manual-reset detection circuit includes built-in debouncing logic that triggers on RESET pin low pulses ≥1.5μs, eliminating external RC networks.

This device operates as a system-level power supervisor: VCC serves as both supply and monitored rail; RESET functions as bidirectional open-drain output with internal pullup; GND provides reference for threshold comparison and timing circuits. It guarantees valid RESET state down to VCC = +1V and rejects transients ≤200mV overdrive for durations under 10μs.

Key Specifications

Pinout & Package

MXD1818UR23+T is housed in a 3-pin SOT23 package (U3-1 outline), footprint-compatible with industry-standard SC70-3 and legacy DS181x devices. The package measures 2.92mm × 1.3mm × 1.0mm and supports reflow soldering per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1818UR23+T, MAX809TRD3+T offers higher threshold and simpler interface but lacks manual-reset functionality, while TPS3808G125DBVR provides lower power and programmable timing at the cost of design complexity and reduced noise immunity in fixed-threshold applications.

Availability

MXD1818UR23+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, set-top box power management, and automotive infotainment head units requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MXD1818UR23+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) designs precision analog and mixed-signal ICs for industrial, communications, computing, and consumer applications, with emphasis on power management, sensing, and interface solutions.

The MXD1810–MXD1818 family was engineered specifically for cost-sensitive, space-constrained μP supervisory roles in battery-powered and thermally demanding environments, delivering factory-trimmed accuracy and integrated functionality in 3-pin SC70/SOT23 packages.

FAQ

What is the exact reset threshold voltage of MXD1818UR23+T and how tightly is it specified?

The MXD1818UR23+T has a factory-set reset threshold of 2.31V, guaranteed over the full operating temperature range of -40°C to +105°C with ±2.5% accuracy. This value is confirmed in the Reset Threshold Table and Electrical Characteristics section of the datasheet, where VTH for suffix "R23" is listed as 2.25V (min), 2.31V (typ), and 2.37V (max). The threshold applies to VCC monitoring and directly determines brownout detection point for +2.5V/+3.0V/+3.3V systems.

Does MXD1818UR23+T support manual reset, and what is the minimum pulse width required?

Yes, MXD1818UR23+T supports debounced manual reset via its RESET pin, which functions as both output and input. A logic-low signal applied to RESET for ≥1.5μs triggers a full 100ms reset assertion period. This feature is explicitly documented for MXD1813/MXD1818 variants and enables direct connection to mechanical switches without external filtering. Release of the switch initiates the timeout, making it ideal for user-accessible reset buttons.

What is the output configuration of MXD1818UR23+T, and does it require an external pullup resistor?

MXD1818UR23+T features an open-drain, active-low RESET output with an internal 5.5kΩ pullup resistor to VCC. No external pullup is required, simplifying design and reducing component count. This configuration allows direct interfacing with bidirectional μP reset pins (e.g., Motorola 68HC11) and supports wired-OR reset architectures. The internal pullup ensures defined logic-high state when RESET is not asserted.

What is the supply current consumption of MXD1818UR23+T at typical operating conditions?

MXD1818UR23+T draws 4μA typical supply current at VCC = +3.6V and room temperature, with a maximum of 10μA across temperature. At +5.5V, typical ICC is 9μA. This ultra-low quiescent current is critical for battery-operated applications such as portable medical devices and wireless sensors, enabling multi-year operation on small coin cells without compromising reset reliability or timing accuracy.

Is MXD1818UR23+T compatible with standard SOT23-3 footprints and reflow processes?

Yes, MXD1818UR23+T uses the industry-standard 3-pin SOT23 package (U3-1 outline), matching land pattern 90-0179 and compatible with automated pick-and-place and lead-free reflow per JEDEC J-STD-020. Its 2.92mm × 1.3mm × 1.0mm dimensions and thermal characteristics support high-volume manufacturing. The "+T" suffix confirms RoHS-compliant, lead-free termination, verified in the Package Information section of the datasheet.