Analog Devices Inc./Maxim Integrated MXD1816UR26

Overview

MXD1816UR26 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 2.55V reset threshold (±2.5% over temperature), 100ms minimum reset timeout, and operates from -40°C to +105°C in SOT23-3 package. It ensures reliable power-on reset in portable battery-powered controllers.

For engineers reviewing the MXD1816UR26 datasheet, MXD1816UR26 pinout, MXD1816UR26 application, or MXD1816UR26 equivalent, key selection criteria include its 2.55V threshold accuracy, open-drain interface compatibility with bidirectional μP reset pins, manual-reset immunity (not supported), and guaranteed RESET validity down to VCC = +1V - critical for brownout detection in embedded instrumentation and set-top boxes.

Technical Context

The MXD1816UR26 implements a precision voltage comparator monitoring VCC against a trimmed bandgap reference to trigger reset when supply drops below 2.55V. Its internal timer guarantees ≥100ms reset assertion after VCC recovery, independent of VCC slew rate.

This device belongs to the MXD1815–MXD1818 subfamily for 2.5V/3.0V/3.3V systems and features open-drain active-low RESET output with integrated pullup - enabling direct connection to μPs like Motorola 68HC11 without external components. It lacks manual-reset debounce circuitry (exclusive to MXD1813/MXD1818).

Key Specifications

Pinout & Package

MXD1816UR26 is housed in a 3-pin SOT23 package (outline U3-1), optimized for space-constrained portable designs. Pin 1 is RESET (open-drain, active-low), Pin 2 is VCC (supply input and threshold monitor), and Pin 3 is GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1816UR26, MAX809TRD3-T offers push-pull drive but lacks internal pullup for bidirectional interfaces, while TPS3808G125DBVR provides configurable timing at the cost of larger package and higher pin count - making MXD1816UR26 optimal for space- and current-constrained 2.55V rail supervision.

Availability

MXD1816UR26 is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, set-top box power management, smart meter MCU supervision, and critical μP monitoring requiring stable component supply across automotive-grade temperature ranges.

Supply support for MXD1816UR26 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, computing, and communications applications.

The MXD1815–MXD1818 product line delivers ultra-low-power, factory-trimmed reset supervisors targeting battery-powered and thermally demanding embedded systems requiring high-accuracy voltage monitoring and deterministic reset timing.

FAQ

What is the exact reset threshold voltage of MXD1816UR26 and how is it specified?

The MXD1816UR26 has a factory-set reset threshold of 2.55V, with guaranteed accuracy of ±2.5% over the full operating temperature range (-40°C to +105°C). This value is defined as the VCC voltage at which the device asserts the active-low RESET signal during falling VCC, and deasserts it after VCC rises above this threshold plus hysteresis. The "R26" suffix in MXD1816UR26 explicitly denotes the 2.55V threshold variant per Maxim's Reset Threshold Table.

Does MXD1816UR26 support manual reset functionality via an external pushbutton?

No, MXD1816UR26 does not include manual reset debounce circuitry. That feature is exclusive to the MXD1813 and MXD1818 variants in the family. MXD1816UR26 provides only power-supply monitoring and automatic reset assertion/deassertion based on VCC crossing the 2.55V threshold. External pushbutton reset would require additional circuitry such as a separate debounced switch interface.

What is the function of the internal pullup resistor in MXD1816UR26 and what is its nominal value?

The MXD1816UR26 includes an internal 5.5kΩ pullup resistor connected to the open-drain RESET output. This allows direct interfacing with microprocessors that have bidirectional reset pins (e.g., Motorola 68HC11) without requiring an external pullup. The resistor ensures RESET remains high when not actively driven low, simplifying design and reducing component count. Its value is specified as 3.5kΩ to 7.5kΩ across process and temperature.

Can MXD1816UR26 operate reliably when VCC drops below 2.0V?

Yes, MXD1816UR26 is guaranteed to maintain correct RESET logic state down to VCC = +1.0V, as confirmed in its Absolute Maximum Ratings and Electrical Characteristics tables. While the reset function activates at 2.55V, the internal comparator and output stage remain functional and predictable even during deep brownout conditions - a key differentiator for fail-safe embedded systems where supply collapse must be detected before complete failure.

Which package type and pinout does MXD1816UR26 use, and is it compatible with other devices in the family?

MXD1816UR26 uses the 3-pin SOT23 package (U3-1 outline) with standard pinout: Pin 1 = RESET (open-drain active-low), Pin 2 = VCC, Pin 3 = GND. It shares identical pinout and footprint with all MXD181xURxx variants (e.g., MXD1815UR31, MXD1817UR26), enabling drop-in replacement within the same voltage-threshold group - provided the application does not require manual reset or push-pull output.