Analog Devices Inc./Maxim Integrated DS1232

Overview

DS1232 from Maxim Integrated (formerly Dallas Semiconductor) is a precision watchdog timer and power-monitor IC for 5V microprocessor systems. It provides three independent functions: VCC monitoring with 4.5V/4.75V trip points, pushbutton reset debouncing with ≥250ms active pulse, and programmable watchdog timeout (150ms/600ms/1.2s), all in an 8-pin mini-DIP package. It is used in embedded controllers where reliable power-up sequencing and software fault recovery are critical.

For engineers reviewing the DS1232 datasheet, DS1232 pinout, DS1232 application, or DS1232 equivalent, key selection considerations include its dual RST outputs (active-high and open-drain active-low), TOL-selectable supply tolerance (5% or 10%), ST input strobe timing requirements, industrial temperature range availability, and absence of watchdog disable capability.

Technical Context

The DS1232 integrates a precision voltage comparator with temperature-compensated reference to detect VCC out-of-tolerance conditions, generating simultaneous active-high and open-drain active-low reset signals. Its power-fail detection holds reset active for ≥250ms after VCC recovery to ensure processor stabilization.

It implements a non-disableable watchdog timer whose timeout is set by TD pin state (GND/float/VCC), producing ≥250ms reset pulses on timeout. The PBRST input provides hardware reset with internal debouncing and guaranteed minimum pulse width, independent of software control.

Key Specifications

Pinout & Package

DS1232 is available in 8-pin mini-DIP (300-mil) and optional 16-pin SOIC (DS1232S). The 8-pin DIP is the standard through-hole package for prototyping and industrial control boards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692A and TPS3823-50, the DS1232 uniquely combines non-disableable watchdog timing, dual reset outputs, and integrated pushbutton handling in one 8-pin IC-making it optimal for systems where software reliability must be enforced without user or debug-mode exceptions.

Availability

DS1232 is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, telecom remote terminals, and automotive body electronics requiring stable component supply and long-term lifecycle support.

Supply support for DS1232 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 (acquired by Analog Devices in 2021) designs precision analog and mixed-signal ICs for industrial, automotive, and communications applications.

The DS1232 belongs to the MicroMonitor™ family of supervisory circuits, engineered specifically to replace discrete reset generators and watchdog timers in 5V microprocessor systems with guaranteed timing and voltage accuracy.

FAQ

What is the function of the TOL pin on the DS1232?

The TOL pin on the DS1232 selects the VCC detection tolerance: when grounded, it configures a 5% threshold (4.75V nominal), and when tied to VCC, it sets a 10% threshold (4.5V nominal). This allows system designers to match the DS1232's power-fail detection to their board's actual 5V supply regulation spec. The DS1232 uses this setting to determine the exact voltage at which RST and RST outputs activate during brownout conditions.

Does the DS1232 support watchdog timer disable?

No, the DS1232 does not support watchdog timer disable. Its watchdog function is always enabled and must be periodically strobed via the ST input to prevent reset assertion. This design enforces continuous software health checking - if the microprocessor fails to generate the required ST transitions, the DS1232 will assert reset. This behavior is intrinsic to the DS1232 and cannot be overridden by configuration or external signals.

What are the timing requirements for the ST input on the DS1232?

The ST input on the DS1232 requires a high-to-low transition before each watchdog timeout expires. Minimum recommended strobe intervals are 62.5ms (TD=GND), 250ms (TD=float), or 500ms (TD=VCC) - based on the minimum timeout values in Table 1. The DS1232 does not specify a maximum ST pulse width, but the transition must be clean and meet VIH/VIL thresholds. Failure to strobe within the selected timeout causes DS1232 to assert both RST outputs for ≥250ms.

How does the DS1232 handle power-up reset timing?

On power-up, the DS1232 holds both RST and RST outputs active for a minimum of 250ms after VCC rises above the selected trip threshold (4.5V or 4.75V), regardless of TD or TOL state. This ensures the microprocessor and supporting circuitry fully stabilize before release. The DS1232 achieves this using an internal power-on reset circuit synchronized to VCC ramp rate, eliminating need for external RC networks. This timing is guaranteed across temperature and supply voltage.

Can the DS1232 be used with 3.3V microprocessors?

The DS1232 is specified only for 5V operation (VCC = 4.5V to 5.5V) and is not rated for direct use with 3.3V systems. Its VCC comparator, reset outputs, and input thresholds are calibrated for 5V logic levels. While the open-drain RST output can be pulled up to 3.3V, the DS1232 itself must be powered from 5V. For 3.3V applications, designers should select a 3.3V-compatible supervisor such as the MAX6326 or TPS3106, not the DS1232.