Analog Devices Inc./Maxim Integrated MXD1816UR23

Overview

MXD1816UR23 from Maxim Integrated is an open-drain, active-low microprocessor reset supervisor IC designed for +2.5V/+3.0V/+3.3V digital systems. It monitors VCC and asserts RESET when supply voltage falls below 2.31V (±2.5% accuracy), maintains reset for ≥100ms after VCC recovery, features internal 5.5kΩ pullup, consumes only 4μA typical supply current, and operates across –40°C to +105°C - ideal for portable battery-powered controllers and embedded μP monitoring.

For engineers reviewing the MXD1816UR23 datasheet, MXD1816UR23 pinout, MXD1816UR23 application, or MXD1816UR23 equivalent, key selection criteria include its 2.31V factory-set threshold, open-drain output compatibility with bidirectional μP reset pins, immunity to sub-5μs VCC transients, guaranteed RESET validity down to VCC = +1V, and SOT23-3 footprint suitability for space-constrained designs.

Technical Context

The MXD1816UR23 implements a precision bandgap-based voltage comparator with hysteresis to detect VCC drops below its 2.31V threshold, triggering an open-drain RESET signal that remains asserted for a minimum 100ms timeout after VCC rises above threshold. Its internal 5.5kΩ pullup resistor eliminates external components while enabling direct interface with μPs having bidirectional reset pins like the Motorola 68HC11.

Unlike MXD1813/MXD1818 variants, MXD1816UR23 lacks manual-reset debounce circuitry and push-button detection logic; it responds solely to VCC monitoring events. Its BiCMOS process ensures stable operation over –40°C to +105°C and transient immunity up to 100μs for 100mV overdrive, with no external timing capacitors required.

Key Specifications

Pinout & Package

MXD1816UR23 is housed in a 3-pin SOT23 package (outline U3-1), with pin 1 = RESET (open-drain, active-low), pin 2 = VCC (supply input and threshold monitor), and pin 3 = GND. The compact 2.92mm × 1.3mm body height of 1.02mm supports automated assembly and thermal performance up to +105°C ambient.

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, MXD1816UR23 delivers optimal fit for fixed 2.31V brownout protection in 3.3V systems - combining ultra-low 4μA current, integrated pullup, and guaranteed operation down to VCC = +1V without design compromises.

Availability

MXD1816UR23 is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, network edge routers, and smart energy meters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MXD1816UR23 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 high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MXD1810–MXD1818 family was engineered specifically for reliable, low-power microprocessor reset supervision in space-constrained, battery-sensitive systems - emphasizing precision threshold accuracy, zero external components, and extended temperature operation.

FAQ

What is the exact reset threshold voltage of MXD1816UR23 and how accurate is it over temperature?

The MXD1816UR23 has a factory-set reset threshold of 2.31V with ±2.5% accuracy over the full –40°C to +105°C operating range. This value is trimmed during production and guaranteed by design, ensuring consistent brownout detection across environmental conditions without calibration. The 2.31V point aligns precisely with the lower margin of 2.5V/3.3V systems, making MXD1816UR23 ideal for early-failure prevention in those rails.

Does MXD1816UR23 support manual reset via an external pushbutton?

No, MXD1816UR23 does not include manual reset debounce functionality. That feature is exclusive to MXD1813 and MXD1818 variants. MXD1816UR23 responds only to VCC-supply monitoring events - it asserts RESET solely when VCC drops below 2.31V and holds it for ≥100ms after VCC recovers. External pushbutton reset requires separate circuitry or selection of MXD1818UR23 instead.

What is the function of the internal pullup resistor in MXD1816UR23 and what value does it have?

The MXD1816UR23 integrates a 5.5kΩ pullup resistor between RESET and VCC, enabling its open-drain output to drive a logic-high state without external components. This allows direct interfacing with microprocessors that have bidirectional reset pins (e.g., Motorola 68HC11), simplifies PCB layout, and reduces BOM cost. The resistor value ensures sufficient rise time while maintaining noise immunity and sink capability up to 10mA.

Can MXD1816UR23 operate reliably when VCC drops below 2.0V?

Yes - MXD1816UR23 is guaranteed to maintain valid RESET output down to VCC = +1.2V (minimum specified), and its reset comparator remains functional with correct logic states down to VCC = +1V. This ensures deterministic behavior during deep brownout conditions where competing supervisors may float or misfire, making MXD1816UR23 especially suited for battery-powered applications with wide discharge curves.

Which package type and footprint does MXD1816UR23 use, and is it RoHS-compliant?

MXD1816UR23 uses the 3-pin SOT23 package (outline U3-1, land pattern 90-0179), measuring 2.92mm × 1.3mm with 1.02mm height. It is available in lead(Pb)-free packaging - indicated by the "+T" suffix in ordering codes - and fully complies with RoHS Directive 2011/65/EU. The SOT23 footprint ensures compatibility with standard pick-and-place equipment and reflow profiles.