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 pulse, and provides watchdog timer with selectable timeouts (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 considerations include dual-reset output polarity, programmable watchdog timeout via TD pin, VCC trip point selection (4.25V or 4.50V), and compatibility with 5V microcontroller power rails requiring guaranteed 250 ms reset assertion on power-up and brownout.

Technical Context

The DS1232SN+ integrates three independent monitoring functions in a single 8-pin DIP package: precision voltage detection using a temperature-compensated bandgap reference and comparator, hardware-debounced pushbutton reset with fixed 250 ms minimum pulse width, and a non-disableable watchdog timer with three timeout options 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 or pull-up components; the open-drain RST supports wired-OR configurations and mixed-voltage systems, while the active-high RST drives standard TTL/CMOS inputs directly.

Key Specifications

Pinout & Package

DS1232SN+ uses an 8-pin mini-DIP (0.300" wide) 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; pin 4 is GND; pin 8 is VCC; pin 7 is ST (strobe input); pin 1 is PBRST (pushbutton reset input).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692AESA+ and TPS3823DBVR, DS1232SN+ uniquely provides simultaneous active-high and open-drain active-low reset outputs plus user-selectable VCC trip point and watchdog timeout-enabling robust, adaptable supervision in space-constrained industrial controllers without external components.

Availability

DS1232SN+ is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, automotive body electronics, and point-of-sale terminal designs requiring stable component supply and long-term lifecycle support.

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 reliable microprocessor reset generation, power supply monitoring, and watchdog protection in harsh industrial environments.

FAQ

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

The TOL pin on the DS1232SN+ selects the VCC detection threshold: when tied to GND, DS1232SN+ triggers reset at 4.50 V (5% drop from 5 V); when tied to VCC, it triggers at 4.25 V (10% drop). This allows system designers to match the reset activation point to their specific power supply regulation tolerance and noise margin requirements without changing the IC.

Does the DS1232SN+ require external components to operate?

No, the DS1232SN+ operates autonomously with no external timing capacitors or resistors required. Its internal precision reference, comparator, and watchdog timer are fully self-contained. Only basic decoupling (0.1 µF ceramic capacitor near VCC) and optional pull-up on open-drain RST are recommended per layout guidelines-no external components are needed for core supervision functionality.

Can the watchdog timer on the DS1232SN+ be disabled?

No, the watchdog timer on the DS1232SN+ cannot be disabled. It is always active and must be strobed via the ST input at intervals shorter than the selected timeout (150/600/1200 ms) to prevent automatic reset assertion. This design ensures fail-safe behavior: if firmware hangs or fails to service the watchdog, DS1232SN+ will force a system reset.

What is the significance of having both RST and RST outputs on the DS1232SN+?

The DS1232SN+ provides two physically separate reset outputs: RST (Pin 5) is active-high CMOS, and RST (Pin 6) is active-low open-drain. This dual-output architecture allows direct connection to microprocessors requiring either polarity reset signal-and enables wired-OR reset busing via the open-drain output-without external logic or level shifters, reducing board area and BOM count.

Is the DS1232SN+ compatible with modern 5V microcontrollers?

Yes, the DS1232SN+ is fully compatible with modern 5V microcontrollers. Its VCC operating range (4.5 V to 5.5 V), CMOS-compatible active-high RST output, open-drain RST with 10 mA sink capability, and 250 ms minimum reset pulse meet or exceed requirements of contemporary 5V MCUs including ARM Cortex-M0/M3, PIC18, and legacy 8051 derivatives used in industrial control and instrumentation.