Analog Devices Inc./Maxim Integrated MXD1816XR29+T

Overview

MXD1816XR29+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 voltage falls below 2.88V (±2.5% accuracy), maintains reset for ≥100ms after VCC recovery, features internal 5.5kΩ pullup, consumes only 4μA typical supply current, and operates from –40°C to +105°C in SC70-3 package - ideal for portable battery-powered μP monitoring.

For engineers reviewing the MXD1816XR29+T datasheet, MXD1816XR29+T pinout, MXD1816XR29+T application, or MXD1816XR29+T equivalent, key selection criteria include its 2.88V factory-trimmed threshold, open-drain output compatibility with bidirectional μP reset pins (e.g., Motorola 68HC11), immunity to sub-5µs VCC transients, guaranteed RESET validity down to VCC = +1V, and lead-free SC70 packaging for space-constrained embedded designs.

Technical Context

The MXD1816XR29+T implements a precision bandgap-based reset comparator with ±2.5% threshold accuracy over temperature and built-in transient rejection logic that ignores VCC glitches shorter than ~2–5µs depending on overdrive. Its open-drain RESET output interfaces directly with bidirectional microcontroller reset inputs without external pullups.

This device belongs to the MXD1815–MXD1818 subgroup optimized for 2.5V/3.0V/3.3V supplies and uses BiCMOS process technology to achieve 4μA quiescent current while maintaining robust reset timing (tRP = 100–250ms) and valid logic states down to VCC = +1V - enabling reliable brownout detection in low-power portable systems.

Key Specifications

Pinout & Package

MXD1816XR29+T is housed in a 3-pin SC70 package (outline X3-2, land pattern 90-0208), measuring 2.0mm × 1.25mm × 0.9mm, suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1816XR29+T, MAX809TRD3+T offers lower supply current but lacks integrated pullup and has different threshold; TPS3808G125DBVR provides adjustability and ultra-low ICC but demands layout changes and external components - making MXD1816XR29+T optimal for drop-in 2.88V open-drain reset in space-constrained 3.3V systems.

Availability

MXD1816XR29+T is available at Aetrix Electronics and suitable for computers and controllers, intelligent instruments, and portable/battery-powered equipment requiring stable component supply across industrial temperature ranges and long-term production continuity.

Supply support for MXD1816XR29+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, and computing applications, emphasizing reliability, integration, and low-power operation.

The MXD1815–MXD1818 product line delivers highly accurate, ultra-low-power reset supervision for 2.5V/3.0V/3.3V microprocessor systems - targeting portable instrumentation, set-top boxes, and embedded controllers where board space and battery life are critical.

FAQ

What is the exact reset threshold voltage of MXD1816XR29+T and how tightly is it specified?

The MXD1816XR29+T has a factory-set reset threshold of 2.88V, with guaranteed accuracy of ±2.5% over the full operating temperature range (–40°C to +105°C). This value is confirmed in the Electrical Characteristics table under "MXD181_ _ R29" entry, where min/typ/max are 2.80V/2.88V/2.97V. The threshold is trimmed during production and does not require external calibration.

Does MXD1816XR29+T include an internal pullup resistor, and what is its nominal value?

Yes, MXD1816XR29+T includes an internal pullup resistor on its open-drain RESET pin, with a nominal value of 5.5kΩ (min 3.5kΩ, max 7.5kΩ). This is explicitly stated in the Electrical Characteristics table under "Internal Pullup Resistor, Open-Drain" for MXD1816, eliminating the need for an external pullup in standard interfacing scenarios.

Can MXD1816XR29+T be used with microcontrollers that have bidirectional reset pins?

Yes, MXD1816XR29+T is specifically suited for microcontrollers with bidirectional reset pins (e.g., Motorola 68HC11) due to its open-drain active-low RESET output and internal 5.5kΩ pullup. The Applications Information section confirms direct interface capability without external components, enabling either the μP or MXD1816XR29+T to assert reset on the shared line.

What is the minimum supply voltage at which MXD1816XR29+T guarantees valid RESET output logic levels?

MXD1816XR29+T guarantees valid RESET output logic states down to VCC = +1.0V, as stated in both the General Description and Absolute Maximum Ratings sections. This ensures deterministic reset behavior during deep brownout conditions before complete power loss - a key reliability feature for battery-backed systems.

Is MXD1816XR29+T compatible with lead-free PCB assembly processes?

Yes, MXD1816XR29+T is supplied in lead(Pb)-free packaging, indicated by the "+T" suffix per Maxim's ordering convention. The datasheet confirms RoHS-compliant packaging and specifies a maximum soldering temperature of +300°C for 10 seconds, fully supporting standard lead-free reflow profiles.