Analog Devices Inc./Maxim Integrated MXD1818XR23

Overview

MXD1818XR23 from Maxim Integrated is a low-power microprocessor reset supervisor IC with open-drain active-low RESET output, manual-reset debouncing, and factory-trimmed 2.31V reset threshold. It monitors +2.5V/+3.0V/+3.3V power supplies, asserts reset for ≥100ms after VCC recovery or external push-button release, and operates from -40°C to +105°C in SC70-3 package. Used in portable battery-powered systems requiring reliable brownout protection.

For engineers reviewing the MXD1818XR23 datasheet, MXD1818XR23 pinout, MXD1818XR23 application, or MXD1818XR23 equivalent, key selection criteria include its 2.31V ±2.5% threshold accuracy, 4μA supply current at +3.6V, internal 5.5kΩ pullup resistor, 1.5μs minimum manual-reset detect pulse width, and guaranteed RESET validity down to VCC = +1V.

Technical Context

The MXD1818XR23 implements a precision voltage comparator with hysteresis-free threshold detection and an internal monostable timer that enforces a fixed 100ms (min) reset timeout period upon VCC rise above 2.31V or external RESET pin assertion. Its debounced manual-reset input detects logic-low pulses ≥1.5μs on the RESET terminal and triggers a synchronized 100ms reset hold time independent of VCC transient behavior.

This device uses BiCMOS process technology to achieve 4μA typical supply current while maintaining ±2.5% reset threshold accuracy over full temperature range (-40°C to +105°C), immunity to fast VCC transients (<100ns), and valid reset signaling down to VCC = +1V - enabling robust operation in low-voltage portable systems where supply rails may sag during battery discharge.

Key Specifications

Pinout & Package

MXD1818XR23 is housed in a 3-pin SC70 package (outline X3-2), footprint-compatible with SOT23-3 but 30% smaller. The package supports reflow soldering and is available in lead(Pb)-free form (designated by "+T" suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD3-T and TPS3808G125DBVR, MXD1818XR23 delivers tighter 2.31V threshold accuracy (±2.5%), integrated manual-reset debouncing, and ultra-small SC70-3 footprint - making it optimal for space-constrained, battery-sensitive designs needing both power-fail and user-initiated reset functionality.

Availability

MXD1818XR23 is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart energy meters, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MXD1818XR23 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 high-performance analog and mixed-signal semiconductor solutions for industrial, communications, computing, and consumer applications.

The MXD1810–MXD1818 family targets cost-sensitive, space-constrained embedded systems requiring reliable, low-power power-supply monitoring and manual reset capability without external components.

FAQ

What is the exact reset threshold voltage of MXD1818XR23 and how is it trimmed?

The MXD1818XR23 has a factory-trimmed reset threshold of 2.31V with ±2.5% accuracy over the full -40°C to +105°C temperature range. This value is laser-trimmed during production and verified per the Reset Threshold Table in the datasheet; no external adjustment is possible or required. The "R23" suffix explicitly denotes this 2.31V variant within the MXD1815–MXD1818 series for 2.5V/3.0V/3.3V systems.

Does MXD1818XR23 support manual reset, and what are the timing requirements?

Yes, MXD1818XR23 supports hardware-debounced manual reset via its RESET pin. An externally applied logic-low signal held for ≥1.5μs triggers a guaranteed 100ms (minimum) reset timeout period. Release of the external switch initiates the timeout - no additional edge detection or firmware logic is needed. This feature is exclusive to MXD1813/MXD1818 variants and is confirmed in the Pin Descriptions and Detailed Description sections.

What package type and footprint does MXD1818XR23 use, and is it RoHS compliant?

MXD1818XR23 uses the 3-pin SC70 package (outline X3-2, land pattern 90-0208), which is 30% smaller than SOT23-3. It is available in lead(Pb)-free form - indicated by the "+T" suffix in ordering codes - and fully complies with RoHS Directive 2011/65/EU. The "XR" in the part number specifically denotes the SC70 package variant, distinct from "UR" (SOT23) versions.

How does MXD1818XR23 behave when VCC drops below 1.0V, and is RESET still valid?

MXD1818XR23 guarantees correct RESET logic state only down to VCC = +1.0V, as specified in Absolute Maximum Ratings and Electrical Characteristics. Below +1.0V, the internal circuitry cannot maintain defined output behavior; the open-drain RESET pin will float or drift due to diminished sinking capability and internal pullup dominance. For applications requiring valid reset signaling at VCC = 0, external pulldown/pullup resistors (as shown in Figures 8–9) are necessary - but MXD1818XR23 itself does not support sub-1V operation.

Can MXD1818XR23 interface directly with microcontrollers having bidirectional reset pins?

Yes, MXD1818XR23 can interface directly with bidirectional μP reset pins (e.g., Motorola 68HC11) because its open-drain RESET output includes an internal 5.5kΩ pullup resistor to VCC. This eliminates the need for an external pullup and allows either the supervisor or the μP to drive the shared reset line low. The datasheet explicitly confirms this capability in the Applications Information section and Figure 7.