Analog Devices Inc./Maxim Integrated DS1231-50N

Overview

DS1231-50N from Maxim Integrated is a power monitor IC that detects impending power failure by monitoring both high-voltage input (IN) and +5V supply (VCC), provides dual reset outputs (RST active-high, RST active-low open-drain), and generates non-maskable interrupt (NMI) with mode-selectable input characteristics. It supports 5% VCC threshold detection (TOL = GND → 4.50–4.74 V trip), operates from 0°C to 70°C, and requires no external capacitors.

For engineers reviewing the DS1231-50N datasheet, DS1231-50N pinout, DS1231-50N application, or DS1231-50N equivalent, this device delivers precise early-warning power loss detection, automatic processor restart after recovery, and flexible high-voltage sensing via opto-isolator or resistor-divider interfaces - critical for industrial control, embedded systems with nonvolatile memory, and power-critical microprocessor platforms.

Technical Context

The DS1231-50N integrates two independent comparators: one monitors VCC against a temperature-compensated reference to assert RST/RST at selectable 5% or 10% thresholds, and another monitors the IN pin with hysteresis (±60 mV) and mode-selectable input behavior (high-impedance when MODE = VCC; 30 µA current source when MODE = GND). Its digital sampler and delay logic ensure deterministic timing between NMI assertion and final reset.

It features dual reset outputs with distinct electrical roles: RST is active-high push-pull (VOL ≤ 0.4 V @ –500 µA, VOH ≥ VCC–0.5 V), while RST is active-low open-drain (requires external pull-up), enabling direct interface to diverse microprocessor reset inputs. Power-up reset pulse width is guaranteed ≥150 ms.

Key Specifications

Pinout & Package

DS1231-50N is supplied in an 8-pin DIP package (300 mil width), with pins arranged linearly and compatible with through-hole PCB assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power monitor applications.

Compared with MAX690CPA+ and TPS3823-50DBVR, DS1231-50N uniquely combines NMI-based early warning, dual-reset signaling, and MODE-selectable high-voltage input - making it irreplaceable in applications requiring coordinated shutdown of nonvolatile memory operations under AC line disturbance.

Availability

DS1231-50N is available at Aetrix Electronics and suitable for industrial control systems, medical diagnostic equipment, embedded data loggers, and point-of-sale terminals requiring stable component supply and long-term lifecycle support.

Supply support for DS1231-50N 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, automotive, and communications markets.

The DS1231-50N belongs to Maxim's power supervision product line, engineered specifically for robust, early-detection power failure response in microprocessor-based systems with nonvolatile memory - emphasizing fail-safe shutdown and clean restart.

FAQ

What is the function of the MODE pin on the DS1231-50N?

The MODE pin on the DS1231-50N selects the electrical behavior of the IN pin: when tied to VCC, IN becomes a high-impedance input (VTP− = 2.3 V) for resistor-divider sensing; when grounded, IN sources 30 µA (VTP+ = 2.5 V) to directly drive opto-isolator LEDs. This dual-mode capability makes DS1231-50N adaptable to both isolated and non-isolated power monitoring topologies without external components.

How does the DS1231-50N determine its VCC reset threshold?

The DS1231-50N sets its VCC reset threshold via the TOL pin: connecting TOL to GND selects a 5% threshold (4.50–4.74 V), while connecting TOL to VCC selects a 10% threshold (4.25–4.49 V). This selection directly configures the internal comparator reference, eliminating the need for external resistor networks and ensuring repeatable, temperature-stable trip points across the operating range of DS1231-50N.

Why does the DS1231-50N provide both RST and RST outputs?

The DS1231-50N provides RST (active-high push-pull) and RST (active-low open-drain) to support heterogeneous microprocessor reset requirements: RST interfaces directly with processors expecting active-high reset (e.g., many 8051 derivatives), while RST enables wired-OR reset buses or level-shifted interfaces via external pull-up. This dual-output architecture ensures DS1231-50N compatibility across legacy and modern designs without redesigning reset circuitry.

Does the DS1231-50N require external capacitors for operation?

No, the DS1231-50N requires no external capacitors for core functionality. Its internal temperature-compensated reference, digital delay logic, and comparator hysteresis eliminate reliance on external timing or filtering components. This simplifies layout, improves long-term reliability, and removes capacitor-related failure modes - a key design advantage of DS1231-50N over RC-based reset solutions.

What is the purpose of the NMI output on the DS1231-50N?

The NMI output on the DS1231-50N delivers an early, non-maskable interrupt signal upon detection of input voltage (IN) or VCC deviation, providing maximum time for firmware-initiated actions - such as saving volatile data to nonvolatile memory - before final reset assertion. Unlike RST/RST, NMI is asserted first (tIPU = 200 µs), making DS1231-50N uniquely suited for systems where data integrity depends on pre-reset software intervention.