Analog Devices Inc./Maxim Integrated DS1232SN

Overview

DS1232SN from Maxim Integrated (formerly Dallas Semiconductor) is a microprocessor supervisory circuit that monitors VCC, implements pushbutton reset with 250 ms debounced output, and provides a selectable watchdog timer (150/600/1200 ms). It delivers active-high and open-drain active-low reset outputs, supports 5% or 10% VCC tolerance via TOL pin, and operates across -40°C to +85°C for industrial embedded control systems.

For engineers reviewing the DS1232SN datasheet, DS1232SN pinout, DS1232SN application, or DS1232SN equivalent, key selection criteria include dual-reset output polarity, programmable watchdog timeout, VCC trip point selection (4.25 V or 4.50 V), industrial temperature rating, and 8-pin mini-DIP package compatibility with legacy designs.

Technical Context

The DS1232SN integrates three independent monitoring functions: precision voltage detection using a temperature-compensated bandgap reference and comparator, hardware-debounced pushbutton reset with guaranteed 250 ms minimum pulse width, and a non-disableable watchdog timer whose timeout is set by TD pin state (GND/float/VCC).

Its dual RST outputs-active-high CMOS and active-low open-drain-enable direct interface to diverse microprocessor reset inputs without external level-shifting; the open-drain RST supports wired-OR configurations and pull-up flexibility, while the CMOS RST drives logic directly with 8 mA sink/source capability at 2.4 V/0.4 V.

Key Specifications

Pinout & Package

DS1232SN is supplied in an 8-pin mini-DIP (300-mil) package with through-hole mounting. Pin 1 is PBRST; pins 5 and 6 are dual RST outputs; pin 3 is TOL for VCC tolerance selection; pin 2 is TD for watchdog timeout configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692ACSA+ and TPS3823-50DBVR, the DS1232SN uniquely combines dual-polarity reset, user-selectable VCC trip point, hardware-debounced pushbutton interface, and programmable watchdog timeout-all in a legacy-compatible 8-pin DIP, making it optimal for industrial upgrades requiring functional completeness without PCB redesign.

Availability

DS1232SN is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and point-of-sale terminal designs requiring stable component supply, long-term lifecycle support, and drop-in compatibility with existing Dallas/Maxim supervisory circuits.

Supply support for DS1232SN 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, and communications applications.

The DS1232SN belongs to the MicroMonitor™ family of supervisory circuits engineered specifically for robust microprocessor reset and watchdog control in mission-critical embedded systems operating under variable power and thermal conditions.

FAQ

What is the function of the TOL pin on the DS1232SN?

The TOL pin on the DS1232SN selects the VCC detection threshold: grounded for 5% tolerance (4.50 V nominal trip), or tied to VCC for 10% tolerance (4.25 V nominal trip). This allows designers to match the DS1232SN's power-fail response to their system's supply regulation and noise margin. The DS1232SN uses this setting to determine when to assert its dual RST outputs during brownout conditions.

Does the DS1232SN require external components to operate?

No, the DS1232SN operates autonomously with no external resistors or capacitors required for core functions. Its internal reference, debounce circuitry, and watchdog timer are fully self-contained. Only standard VCC decoupling (0.1 µF ceramic) and optional external pull-up on the open-drain RST output are recommended. The DS1232SN achieves this integration while maintaining pin compatibility with legacy 8-pin supervisory designs.

Can the watchdog timer on the DS1232SN be disabled?

No, the watchdog timer on the DS1232SN 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 selected timeout interval (150/600/1200 ms). This design ensures fail-safe behavior: if firmware hangs or fails to service the watchdog, the DS1232SN will force reset. The DS1232SN relies on continuous strobing as the sole method to maintain normal operation.

What is the difference between the two RST outputs on the DS1232SN?

The DS1232SN provides two physically separate reset outputs: RST is an active-high CMOS output capable of sourcing/sinking 8 mA, while the second RST is an active-low open-drain output requiring an external pull-up. This dual-output architecture allows the DS1232SN to interface directly with MCUs requiring either reset polarity without additional logic. Both outputs are asserted simultaneously and held active for ≥250 ms during power-up or fault events.

Is the DS1232SN pin-compatible with other MicroMonitor devices?

The DS1232SN shares the same 8-pin mini-DIP footprint and core pinout (PBRST, TD, TOL, GND, RST, RST, ST, VCC) with the DS1232 and DS1232L, differing only in temperature grade (N = industrial -40°C to +85°C). It is not pin-compatible with 16-pin SOIC variants like DS1232S due to different pin count and assignment. Designers upgrading from commercial-grade DS1232 can use DS1232SN without layout changes.