Analog Devices Inc./Maxim Integrated MXD1815XR31+T

Overview

MXD1815XR31+T from Maxim Integrated is a low-power microprocessor reset supervisor IC designed to monitor +2.5V/+3.0V/+3.3V supply rails and assert an active-low, open-drain RESET signal when VCC falls below 3.06V (±2.5% over temperature), with a guaranteed 100ms minimum reset timeout period and internal 5.5kΩ pullup resistor - used in portable battery-powered controllers and embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MXD1815XR31+T datasheet, MXD1815XR31+T pinout, MXD1815XR31+T application, or MXD1815XR31+T equivalent, key selection criteria include its 3.06V factory-trimmed threshold, SC70-3 package, 4µA typical supply current at +3.6V, -40°C to +105°C operation, and compatibility with bidirectional μP reset pins without external pullups.

Technical Context

The MXD1815XR31+T implements a precision bandgap-based voltage comparator with hysteresis to detect VCC drops below 3.06V, coupled to a monostable timer that guarantees ≥100ms RESET assertion after VCC recovery. Its open-drain output interfaces directly with bidirectional microcontroller reset inputs (e.g., Motorola 68HC11) without external components.

Unlike push-pull variants, MXD1815XR31+T lacks manual-reset debounce logic (exclusive to MXD1813/MXD1818), and does not support external pushbutton-triggered reset - it functions solely as a supply-voltage monitor with fixed timing and no user-initiated reset capability.

Key Specifications

Pinout & Package

MXD1815XR31+T is housed in a 3-pin SC70 package (outline X3-2, land pattern 90-0208), with pin 1 = RESET (open-drain active-low), pin 2 = VCC (supply and threshold monitor input), pin 3 = GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MXD1815XR31+T, MAX809TRD3+T offers lower supply current but requires an external pullup, while TPS3808G30DBVR provides adjustable timing and push-pull drive at higher ICC and larger package - MXD1815XR31+T balances integrated pullup, SC70 size, and 3.06V precision for cost-sensitive portable 3.3V systems.

Availability

MXD1815XR31+T is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, smart home hubs, and wearable fitness trackers requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MXD1815XR31+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) is a semiconductor company specializing in analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MXD1815XR31+T belongs to the MXD1815–MXD1818 family of low-power μP reset supervisors targeting 2.5V/3.0V/3.3V systems, designed to replace discrete reset circuits with integrated, space-saving, and highly accurate voltage monitoring.

FAQ

What is the exact reset threshold voltage of MXD1815XR31+T and how tightly is it specified?

The MXD1815XR31+T has a factory-set reset threshold of 3.06V, with ±2.5% accuracy guaranteed over the full operating temperature range of -40°C to +105°C. This specification is confirmed in the Electrical Characteristics table under "Reset Threshold" for suffix R31, and applies to all units regardless of batch or date code. The MXD1815XR31+T achieves this precision using laser-trimmed BiCMOS bandgap references, eliminating need for external calibration.

Does MXD1815XR31+T support manual reset via an external pushbutton?

No, MXD1815XR31+T does not support manual reset functionality. That feature is exclusive to the MXD1813 and MXD1818 variants, which include debounced RESET pin detection requiring ≥1.5µs low pulse. The MXD1815XR31+T is a dedicated supply-monitoring reset IC with no input for external reset initiation - its RESET output responds only to VCC voltage transitions relative to the 3.06V threshold.

What package type and dimensions does MXD1815XR31+T use, and is it lead-free?

MXD1815XR31+T uses the SC70-3 package (outline X3-2), measuring 2.0mm × 1.25mm × 0.95mm with 0.65mm pin pitch. It is supplied in lead(Pb)-free packaging, as indicated by the "+T" suffix per Maxim's ordering convention - replacing "-T" with "+T" explicitly denotes RoHS-compliant, matte-tin lead finish per JEDEC J-STD-609A Class 2a standards.

Can MXD1815XR31+T operate reliably down to 1.2V VCC, and what happens to RESET output below that?

Yes, MXD1815XR31+T is fully specified to operate down to VCC = 1.2V (minimum), with guaranteed RESET/RESET logic state validity per Absolute Maximum Ratings and Electrical Characteristics. Below 1.2V, the device ceases functional operation and RESET output becomes indeterminate - however, the IC remains undamaged, and resumes correct behavior once VCC rises above 1.2V. The MXD1815XR31+T does not require external pulldown/pullup for VCC < 1.2V operation.

How does the internal 5.5kΩ pullup resistor in MXD1815XR31+T affect interfacing with a microcontroller's bidirectional reset pin?

The internal 5.5kΩ pullup resistor in MXD1815XR31+T enables direct connection to bidirectional μP reset pins (e.g., Motorola 68HC11) without external components - when the μP asserts reset, it overrides the pullup by sinking current; when idle, the pullup holds RESET high. This eliminates risk of bus contention and simplifies layout. The MXD1815XR31+T's open-drain architecture ensures clean wired-OR capability with other supervisors sharing the same reset line.