Analog Devices Inc./Maxim Integrated DS1232S+T&R

Overview

DS1232S+T&R from Maxim Integrated (formerly Dallas Semiconductor) is a microprocessor supervisory circuit that monitors VCC supply voltage, implements a watchdog timer, and manages pushbutton reset-providing active-high and open-drain active-low reset outputs. It supports 5% or 10% VCC tolerance detection (4.50–4.74 V or 4.25–4.49 V), delivers ≥250 ms reset pulse width, and operates across -40°C to +85°C in industrial environments. Used in embedded controllers where reliable power-up sequencing and fault recovery are critical.

For engineers reviewing the DS1232S+T&R datasheet, DS1232S+T&R pinout, DS1232S+T&R application, or DS1232S+T&R equivalent, key selection considerations include dual-reset output polarity, programmable watchdog timeout (150/600/1200 ms), TOL-selectable VCC threshold, ST strobe interface timing, and SOIC-16 package compatibility with legacy DIP-8 footprints via adapter.

Technical Context

The DS1232S+T&R integrates three independent monitoring functions: precision voltage monitoring using an internal temperature-compensated reference and comparator, debounced pushbutton reset with guaranteed 250 ms minimum active pulse, and a non-disableable watchdog timer with three selectable timeout intervals set by the TD pin state (GND/float/VCC). All functions drive dual RST outputs-one active-high CMOS, one active-low open-drain-enabling flexible interface with diverse microprocessor reset inputs.

Power-on reset is asserted for ≥250 ms after VCC rises above threshold; power-fail detection triggers reset within 175 μs of VCC falling below threshold. The ST input requires periodic high-to-low transitions to prevent timeout, and PBRST accepts active-low pushbutton signals with internal pull-up (10 kΩ typical) and 20 ms debounce delay.

Key Specifications

Pinout & Package

DS1232S+T&R is supplied in a 16-pin SOIC (300-mil) surface-mount package, pin-compatible with the DS1232S variant and functionally aligned with the 8-pin DIP version but with NC pins added for mechanical symmetry.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326UT46D3+ and TPS3808G33DBVR, the DS1232S+T&R uniquely combines dual-polarity reset outputs, selectable VCC threshold, built-in pushbutton debouncing, and programmable watchdog-all in a single 16-pin SOIC. This integration reduces component count and PCB area versus discrete solutions or function-limited alternatives.

Availability

DS1232S+T&R is available at Aetrix Electronics and suitable for industrial control systems, medical diagnostics equipment, automotive body electronics, and networked building automation requiring stable component supply and long-term lifecycle support.

Supply support for DS1232S+T&R 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, automotive, communications, and computing applications.

The DS1232S+T&R belongs to the MicroMonitor™ family of supervisory circuits engineered specifically for robust microprocessor reset management in mission-critical embedded systems operating under variable power and thermal conditions.

FAQ

What is the function of the TOL pin on the DS1232S+T&R?

The TOL pin on the DS1232S+T&R selects the VCC detection tolerance: connecting TOL to GND sets a 5% threshold (trip at 4.50–4.74 V), while connecting it to VCC sets a 10% threshold (trip at 4.25–4.49 V). This allows designers to match the DS1232S+T&R's brown-out response to their system's power supply regulation accuracy without changing components.

Does the DS1232S+T&R support both active-high and active-low reset signaling?

Yes, the DS1232S+T&R provides two independent reset outputs: Pin 15 (RST) is an active-high CMOS output, and Pin 14 (RST) is an active-low open-drain output. This dual-output architecture enables direct interfacing with microprocessors requiring either reset polarity, eliminating the need for external inverters or pull-up resistors in many cases.

Can the watchdog timer in the DS1232S+T&R be disabled?

No, the watchdog timer in the DS1232S+T&R cannot be disabled-it is always active. To prevent unwanted resets, the ST (strobe) input must receive a high-to-low transition at least once per configured timeout interval (150 ms, 600 ms, or 1.2 s). This design ensures fail-safe behavior: if firmware hangs or fails to strobe ST, the DS1232S+T&R will force a reset.

What is the minimum reset pulse width guaranteed by the DS1232S+T&R?

The DS1232S+T&R guarantees a minimum reset pulse width of 250 ms for both RST outputs-whether triggered by power-up, power-down, or pushbutton reset. This duration is sufficient to ensure complete microprocessor initialization and clock stabilization, and is maintained regardless of VCC slew rate or ambient temperature within the specified operating range.

How does the DS1232S+T&R handle pushbutton input debouncing?

The DS1232S+T&R internally debounces the PBRST input using an RC-based timing circuit, providing a 20 ms delay before asserting reset and guaranteeing a clean ≥250 ms reset pulse upon button release. No external capacitors or firmware polling are required-the DS1232S+T&R handles mechanical switch bounce entirely in hardware.