Analog Devices Inc./Maxim Integrated DS1831A+

Overview

DS1831A+ from Maxim Integrated is a multisupply voltage monitor and reset controller with integrated watchdog timer, designed to supervise 5V and 3.3V power rails plus two user-configurable analog inputs (IN1/IN2). It provides open-drain RST5V and RST3.3V outputs with selectable reset delays (10ms/100ms/1s), precision 1.25V bandgap reference, and watchdog timeout triggered by ST input strobe absence. Used in embedded systems requiring reliable power sequencing and software fault detection.

For engineers reviewing the DS1831A+ datasheet, DS1831A+ pinout, DS1831A+ application, or DS1831A+ equivalent, this page delivers verified functional specifications, validated pin roles, confirmed watchdog timing behavior, real-world reset delay configurations, and direct alternative part comparisons - all grounded in Maxim's official DS1831/A/B datasheet Rev. 0–4/03.

Technical Context

The DS1831A+ integrates dual independent voltage comparators for 5V and 3.3V monitoring, each with programmable tolerance (5%/10%/20%) via TOL5V/TOL3.3V pins and configurable reset hold time (10ms/100ms/1s) via TD5V/TD3.3V pins. Internal operation draws power from the higher of IN5V or IN3.3V, requiring ≥1.0V on at least one supply for output validity.

It adds a dedicated watchdog subsystem absent in DS1831/DS1831B: ST input monitors microprocessor activity, and TDWD selects watchdog timeout (10ms/100ms/1s); WDS output pulses low on timeout and connects directly to PBRST5V/PBRST3.3V for automatic system reset. NMI1 provides a single non-maskable interrupt output referenced to the 1.25V internal bandgap.

Key Specifications

Pinout & Package

DS1831A+ is available in 16-pin 300mil DIP and 16-pin 150mil SO packages. Pin numbering and functions are identical across both packages per Maxim's ordering table and pin assignment diagrams.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multisupply monitoring applications.

Compared with MAX6369KA+T and TPS3808G33DBVR, the DS1831A+ uniquely integrates dual-rail monitoring, user-selectable tolerances/delays, watchdog timer with strobe input, and two auxiliary voltage sense channels - reducing BOM count and PCB area in complex embedded systems requiring comprehensive power and software health supervision.

Availability

DS1831A+ is available at Aetrix Electronics and suitable for industrial automation controllers, telecom infrastructure modules, medical diagnostic devices, and automotive infotainment systems requiring stable component supply and long-term lifecycle support.

Supply support for DS1831A+ 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, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The DS1831A+ belongs to Maxim's Micromonitor™ family of power-supervisory ICs, engineered specifically for robust, multi-rail voltage monitoring and fail-safe system reset in harsh environments with wide temperature and supply variation.

FAQ

What is the function of the TDWD pin on the DS1831A+?

The TDWD pin on the DS1831A+ selects the watchdog timeout period: connecting it to GND yields a minimum 10ms timeout, floating gives 100ms, and tying it to VCC sets 1s. This pin is exclusive to the DS1831A+ variant and controls the WDS output behavior - it has no function on DS1831 or DS1831B. The timeout begins when any RST output becomes inactive, and a transition on the ST pin resets the timer.

Can the DS1831A+ monitor voltages other than 5V and 3.3V?

Yes, the DS1831A+ can monitor additional voltages using IN1 and IN2 inputs, each compared against the internal 1.25V bandgap reference. By adding an external resistor divider (e.g., R1/R2 for IN1), users scale higher voltages like 12V or battery levels down to 1.25V for precise trip-point detection. The DS1831A+ datasheet provides design equations and example circuits for configuring these sense points.

How does the DS1831A+ handle power supply sequencing during startup?

During power-up, the DS1831A+ holds RST5V and RST3.3V active until their respective supply inputs (IN5V or IN3.3V) reach valid voltage levels and remain stable for the time delay set by TD5V or TD3.3V. This ensures microcontrollers and FPGAs do not exit reset until both rails have fully settled - preventing initialization errors caused by premature clock or I/O activation.

Is the DS1831A+ watchdog timer disableable?

No, the DS1831A+ watchdog timer cannot be disabled. The ST input must be strobed regularly to prevent timeout; however, the WDS output may be left unconnected if automatic reset is not required. Leaving WDS open disables the reset action while preserving voltage monitoring functionality - the DS1831A+ continues to assert RST5V/RST3.3V on power faults regardless of ST activity.

What are the key differences between DS1831A+ and DS1831B?

The DS1831A+ replaces the master pushbutton (MPBRST) and one comparator with watchdog timer (ST/WDS) and retains NMI1, while DS1831B replaces the 3.3V pushbutton (PBRST3.3V) with PBST - a pushbutton status output. DS1831A+ supports software fault detection; DS1831B supports reset source identification. Both share identical 5V/3.3V monitoring, tolerance/delay configuration, and package options.